View source for Acorn Electron

{{Short description|Personal computer sold in Britain}}
{{Use dmy dates|date=November 2020}}
{{Use British English|date=December 2013}}
{{Infobox computer
| Name = Acorn Electron
| Logo = 
| image = Acorn Electron 4x3.jpg
| Type = [[8-bit computing|8-bit]] [[microcomputer]]
| Developer = [[Acorn Computers]]
| Released = {{Start date and age|df=yes|1983|08|25}}
| Discontinued = 
| Processor = [[Synertek]] [[6502|SY6502A]] @<br>2 [[megahertz|MHz]] when accessing [[read-only memory|ROM]]<br>1 [[megahertz|MHz]] when accessing [[random-access memory|RAM]]
| Memory = 32 [[kilobyte|KB]] [[random-access memory|RAM]], 32 [[kilobyte|KB]] [[read-only memory|ROM]]
| Media = [[Cassette tape]], [[floppy disk]] (optional), [[ROM cartridge]] (optional)
| Graphics = Ferranti Semiconductor Custom ULA
| Display = [[RF modulator]], [[composite video]], [[RGB]] monitor output, 160×256 (4 or 16 colours), 320×256 (2 or 4 colours), 640×256 (2 colours), 320×200 (2 colours – spaced display with two blank horizontal lines following every 8 pixel lines), 640×200 (2 colours – spaced display)
| Input = [[Keyboard (computing)|Keyboard]]
| Connectivity = 
| OS = [[Acorn MOS]] v1.0
| baseprice = £199 (circa £{{Inflation|UK|199|1983|r=-2}} today)
| sound = [[Square wave (waveform)|Tone]] and [[White noise|noise]] generation
}}

The '''Acorn Electron''' (nicknamed the '''Elk''' inside Acorn<ref name="acornuser198307_elk" /> and beyond<ref name="acornelectronworld56">{{cite web | title=The Acorn Electron | website=Acorn Electron World | url=http://www.acornelectron.co.uk/eug/56/a-acor.html | access-date=16 August 2021}}</ref>) was introduced as a lower-cost alternative to the [[BBC Micro]] educational/[[home computer]], also developed by [[Acorn Computers]], to provide many of the features of that more expensive machine at a price more competitive with that of the [[ZX Spectrum]].<ref name="practicalcomputing198210"/> It has 32 [[kilobyte]]s of [[random-access memory|RAM]], and its [[read-only memory|ROM]] includes [[BBC BASIC]] II together with the [[Acorn MOS|operating system]]. Announced in 1982 for a possible release the same year, it was eventually introduced on 25 August 1983 priced at £199.<ref name="acornuser198307_elk"/>

The Electron is able to save and load programs onto [[compact audio cassette|audio cassette]] via a cable, originally supplied with the computer, connecting it to any standard [[tape recorder]] with the appropriate sockets. It is capable of bitmapped graphics, and can use either a contemporary television set, a colour ([[RGB]]) monitor or a [[monochrome monitor]] as its display. Several expansions were made available to provide many of the capabilities omitted from the BBC Micro. Acorn introduced a general-purpose expansion unit, the Plus 1, offering analogue joystick and parallel ports, together with cartridge slots into which ROM cartridges, providing software, or other kinds of hardware expansions, such as disc interfaces, could be inserted.<ref name="electronuser198407p1" /> Acorn also produced a dedicated [[Floppy disk|disc]] expansion, the Plus 3, featuring a disc controller and 3.5-inch floppy drive.<ref name="plus3"/>

For a short period, the Electron was reportedly the best selling micro in the [[United Kingdom]],<ref name="ElectronUser198601">{{cite magazine |url=https://archive.org/stream/ElectronUserVol3/Electron%20User%20%20Vol%203%20No.5#page/n6/mode/1up |magazine=Electron User |volume=3 |issue=5 |page=7 |publisher=Database Publications |title=Spectrum Toppled |date=February 1986 |access-date=2015-11-01}}</ref> with an estimated 200,000<ref name="homecompweekly19850730">{{ cite news | url=https://archive.org/details/home-computing-weekly-123 | title=Olivetti cash revives Acorn | work=Home Computing Weekly | date=30 July 1985 | access-date=27 November 2020 | page=1 }}</ref> to 250,000 machines<ref name="electronuser198606">{{ cite magazine | url=https://archive.org/stream/ElectronUserVol3/Electron%20User%20%20Vol%203%20No.9#page/n4/mode/1up | title=Is a new model on its way? | magazine=Electron User | date=June 1986 | access-date=27 November 2020 | volume=3 | issue=9 | page=5 | quote=They figure that if the public wants Electrons, and more than 250,000 have been sold so far, then the time may be ripe to bring out an enhanced model }}</ref> sold over its entire commercial lifespan. With production effectively discontinued by Acorn as early as 1985,<ref name="acornuser198505a"/> and with the machine offered in bundles with games and expansions, later being substantially discounted by retailers, a revival in demand for the Electron supported a market for software and expansions without Acorn's involvement.<ref name="electronuser198605"/> Its market for games also helped to sustain the continued viability of games production for the BBC Micro.<ref name="diskuser198810_gameplan"/>

==History==
[[File:Hard reset Acorn Electron.gif|thumb|BASIC prompt after switch-on or hard reset (soft reset was similar but did not contain the Acorn trademark).]]

After [[Acorn Computers]] released the [[BBC Micro]], executives believed that the company needed a less expensive computer for the mass market. In May 1982, when asked about the recently announced Sinclair [[ZX Spectrum]]'s potential to hurt sales of the BBC Micro, priced at £125 for the 16K model compared to around twice that price for the 16K BBC Model A, Acorn co-founder [[Hermann Hauser]] responded that in the third quarter of that year Acorn would release a new £120–150 computer which "will probably be called the Electron", a form of "miniaturised BBC Micro", having 32 KB of RAM and 32 KB of ROM, with "higher resolution graphics than those offered by the Spectrum".<ref name="popcompweekly19830506">{{cite news |url=https://archive.org/details/popular-computing-weekly-1982-05-06/page/n4/mode/1up |title=Sinclair Spectrum stuns BBC |work=Popular Computing Weekly |date=6 May 1982 |access-date=28 September 2020 |page=5}}</ref> Acorn co-founder [[Christopher Curry (businessman)|Chris Curry]] also emphasised the Electron's role as being "designed to compete with the Spectrum... to get the starting price very low, but not preclude expansion in the long term."<ref name="practicalcomputing198210">{{cite news |url=http://chrisacorns.computinghistory.org.uk/docs/Mags/PC/PC_Oct82_CCurry.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://chrisacorns.computinghistory.org.uk/docs/Mags/PC/PC_Oct82_CCurry.pdf |archive-date=2022-10-09 |url-status=live |title=Chris Curry of Acorn |work=Practical Computing |date=October 1982 |access-date=18 October 2020 |pages=62–63, 69, 71 }}</ref>{{rp|pages=63|quote=The Electron is designed to compete with the Spectrum. The idea is to get the starting price very low, but not preclude expansion in the long term.}}

===Development===
In order to reduce component costs, and to prevent cloning, the company reduced the number of chips in the Electron from the 102 on the BBC Micro's motherboard to "something like 12 to 14 chips"<ref name="smith20130823">{{cite web |url=https://www.theregister.co.uk/2013/08/23/acorn_electron_history_at_30/ |title=Acorn's would-be ZX Spectrum killer, the Electron, is 30 |publisher=The Register |work=2013-08-23 |access-date=12 January 2015 |last1=Smith |first1=Tony }}</ref>{{rp|page=1|quote=Central to cutting the cost of the new machine was reducing the chip count. In place of the BBC’s various ancillary logic chips, the Electron would employ a single Uncommitted Logic Array (ULA) chip, a trick Sinclair had employed in the ZX81 and Spectrum; the ZX80 had used off-the-shelf TTL parts. “That allowed us to take a machine which had 102 chips on the motherboard and reduce it to something like 12 or 14 chips,” says Furber, “basically an order of magnitude reduction in the complexity of the motherboard.”}} with most functionality on a single 2,400-gate [[Uncommitted Logic Array]] (ULA).<ref name="popcompweekly19830901" />

The operating system ROM locations 0xFC00-0xFFFF contain the details of some members of the Electron's design team, these differing somewhat from those listed in the corresponding message in the [[BBC Micro|BBC Model B]] ROM:<ref name="acornuser198309_credits">{{ cite magazine | url=https://archive.org/details/AcornUser014-Sep83/page/n30/mode/1up | title=The Elk's 'MOS' Roll Call | magazine=Acorn User | date=September 1983 | access-date=19 October 2022 | pages=29 }}</ref>

{{boxquote|(C) 1983 Acorn Computers Ltd. Thanks are due to the following contributors to the development of the Electron (among others too numerous to mention):- Bob Austin, Astec, Harry Barman, Paul Bond, [[Allen Boothroyd]], Ben Bridgewater, Cambridge, John Cox, [[Christopher Curry (businessman)|Chris Curry]], 6502 designers, Jeremy Dion, Tim Dobson, Joe Dunn, [[Ferranti]], [[Steve Furber]], David Gale, Andrew Gordon, Martyn Gilbert, Lawrence Hardwick, [[Hermann Hauser]], John Herbert, Hitachi, [[Andy Hopper]], Paul Jephcot, Brian Jones, Chris Jordan, [[University of Cambridge Computer Laboratory|Computer Laboratory]], Tony Mann, Peter Miller, Trevor Morris, Steve Parsons, Robin Pain, Glyn Phillips, Brian Robertson, [[Peter Robinson (computer scientist)|Peter Robinson]], David Seal, Kim Spence-Jones, Graham Tebby, Jon Thackray, Topexpress, Chris Turner, [[Advanced Disk Filing System|Hugo Tyson]], John Umney, Alex van Someren, Geoff Vincent, Adrian Warner, Robin Williamson, [[Sophie Wilson|Roger Wilson]].}}

Additionally, the last bytes of both the BASIC ROM and the Plus 3 interface's ADFS v1.0 ROM include the word "Roger", thought to be a reference to [[Sophie Wilson|Roger Wilson]].<ref>{{cite web|url=https://www.bbcbasic.co.uk/bbcbasic/history.html |title=A History of BBC BASIC |last=Russell |first=R. T.}}</ref> The case was designed by industrial designer [[Allen Boothroyd]] of Cambridge Product Design.

===Release===
Reports during the second half of 1982 indicated a potential December release,<ref name="acornuser198209">{{cite magazine |url=https://archive.org/details/AcornUser002-Sep82/page/n6/mode/1up |title=Acorn drops hints on Electron |magazine=Acorn User |date=September 1982 |access-date=18 October 2020 |page=3}}</ref> with Curry providing qualified confirmation of such plans, together with an accurate depiction of the machine's form and capabilities, noting that the "massive [[Uncommitted Logic Array|ULA]]" would be the "dominant factor" in any pre-Christmas release.<ref name="acornuser198210">{{cite magazine |url=https://archive.org/details/AcornUser003-Oct82/page/n6/mode/1up |title=Electron to use add-on modules |magazine=Acorn User |date=October 1982 |access-date=18 October 2020 |page=3}}</ref> As the end of the year approached, the machine itself was pictured in press reports.<ref name="yourcomputer198212_electron">{{ cite magazine | url=https://archive.org/details/your-computer-magazine-1982-12/page/n20/mode/1up | title=First glimpse of Acorn's Electron - the 32K £150 Spectrum rival | magazine=Your Computer | date=December 1982 | access-date=5 January 2024 | pages=21 }}</ref> With the ULA not ready for "main production", however, the launch of the Electron was to be delayed until the spring.<ref name="acornuser198211">{{cite magazine |url=https://archive.org/details/AcornUser004-Nov82/page/n5/mode/2up |title=Electron launch delayed |magazine=Acorn User |date=November 1982 |access-date=18 October 2020 |page=4}}</ref>

By June 1983, with the planned March release having passed, the launch of the Electron had been rescheduled for the [[Acorn User|''Acorn User'' Exhibition]] in August 1983,<ref name="popcompweekly19830602">{{ cite news | url=https://archive.org/details/popular-computing-weekly-1983-06-02/mode/1up | title=The Electron cometh... slowly | work=Popular Computing Weekly | date=2 June 1983 | access-date=30 December 2020 | page=1 }}</ref> and the machine was indeed launched at the event. The company expected to ship the Electron before Christmas, and sell 100,000 by February 1984.<ref name="popcompweekly19830901">{{ cite news | url=https://archive.org/details/popular-computing-weekly-1983-09-01/mode/1up | title=Electron launched... at last | work=Popular Computing Weekly | date=1 September 1983 | access-date=30 December 2020 | pages=1, 5 }}</ref> The price at launch{{snd}}£199{{snd}}remained unchanged from that stated in an announcement earlier in the year, with the machine's nickname within Acorn{{snd}}the "Elk"{{snd}}also being reported publicly for perhaps the first time.<ref name="acornuser198307_elk">{{ cite magazine | url=https://archive.org/details/AcornUser012-Jul83/page/n6/mode/1up | title=Electron set for battle at £199 | magazine=Acorn User | date=July 1983 | access-date=21 August 2021 | pages=5 }}</ref>

Reviews were generally favourable, starting with positive impressions based on the physical design of the computer, with one reviewer noting, "The Electron is beautifully designed and built{{snd}}quite a shock compared to the BBC. Its designer case will look great on the coffee table." Praise was also forthcoming for the Electron's keyboard which was regarded as being better than most of its low-cost peers, with only the [[VIC-20]] being comparable.<ref name="pcn19830825_electron" /> In one review, the keyboard was even regarded as better than the one in the BBC Micro.<ref name="yourcomputer198309_electron" /> The provision of rapid BASIC keyword entry though the combination of the {{keypress|FUNC}} key with various letter keys was also welcomed as a helpful aid to prevent typing errors by "most users", while "touch typists" were still able to type out the keywords in full.<ref name="yourcomputer198309_electron" />

Reviewers also welcomed the machine's excellent graphics compared to its rivals, noting that "the graphics are much more flexible and the maximum resolution is many times that of the Spectrum's". The provision of screen modes supporting 80 columns of readable text and graphics resolutions of 640×256 was described as "unrivalled by every machine up to the BBC Model B itself", although the absence of a [[teletext]] mode was considered regrettable. Although valued for its low memory usage characteristics in the BBC Micro,<ref name="pcw198310_electron">{{ cite news | url=https://archive.org/details/PersonalComputerWorld1983-10/page/160/mode/2up | title=Electron | work=Personal Computer World | date=October 1983 | access-date=22 October 2021 | last1=Mann | first1=Steve | pages=160–163, 165, 167 }}</ref> one reviewer considered the absence of a "software simulation of a teletext screen" to be a "lazy omission" even if it would have to be "awfully slow and take up piles of memory".<ref name="pcn19830825_electron">{{ cite news | url=https://archive.org/details/Personal-Computer-News/PersonalComputerNews025-31Aug1983/page/n25/mode/2up | title=Electronic theory | work=Personal Computer News | date=25 August 1983 | access-date=23 October 2021 | last1=Phillips | first1=Max | pages=24–46 }}</ref>

While its speed was acceptable compared to its immediate competition, the Electron was, however, rather slower than the BBC Micro with one review noting that games designed for the BBC Micro ran "at less than half the speed, with very significant effects on their appeal".<ref name="popcompweekly19830825">{{ cite news | url=https://archive.org/details/popular-computing-weekly-1983-08-25/page/n13/mode/2up | title=How does it compare? | work=Popular Computing Weekly | date=25 August 1983 | access-date=30 December 2020 | last1=Brain | first1=Keith | last2=Brain | first2=Steven | pages=14–15 }}</ref> The reduced performance can be attributed to the use of a 4-bit wide memory system instead of the 8-bit wide memory system of the [[BBC Micro]] to reduce cost. Due to needing two accesses to the memory instead of one to fetch each byte, along with contention with the video hardware also needing access, reading or writing RAM was much slower than on the BBC Micro.<ref name="acornuser198309">{{ cite magazine | url=https://archive.org/details/AcornUser014-Sep83/page/n27/mode/2up | title=Speed - The Big Difference | magazine=Acorn User | date=September 1983 | access-date=30 October 2020 | last1=Beverley | first1=Paul | pages=26–27}}</ref>{{rp|page=26|quote=As you can see, in the worst case, the Electron takes 4.3 times as long to run the same program as the BBC micro.}} Reviewers were also disappointed by the single-channel sound, noting that "BBC-style music" and its "imitations of various musical instruments" would not be possible, the latter due to the inability of the sound system to vary the amplitude of sounds.<ref name="yourcomputer198309_electron">{{ cite news | url=https://archive.org/details/your-computer-1983-09_202007/page/57/mode/2up | title=Review Electron | work=Your Computer | date=September 1983 | access-date=22 October 2021 | last1=Cryer | first1=Neil | pages=56–57, 59 }}</ref>

Despite some uncertainty about Acorn's target demographic for the Electron, some noted the potential for the machine in education given its robustness,<ref name="yourcomputer198309_electron" /> but also given its price, noting that the high price of BBC Model B machines seemed "rarely justified by their actual practical applications in schools". The introduction of the Electron was seen as potentially leading to competition between Acorn's different models within the schools market rather than creating a broader audience for them, although the potential for more computers in schools, giving more "hands-on" experience for students, was welcomed.<ref name="popcompweekly19830825" /> Nevertheless, reviewers anticipated that the Electron would sell well at the lower end of the market, with projected sales of 100,000 units by Christmas 1983,<ref name="practicalcomputing198310_electron">{{ cite news | url=https://archive.org/details/PracticalComputing1983October/page/n65/mode/2up | title=Electron | work=Practical Computing | date=October 1983 | access-date=22 October 2021 | last1=Maude | first1=Neville | pages=68–70 }}</ref> helped by the Electron's software compatibility with the BBC Micro and the already established reputation of its predecessor.<ref name="yourcomputer198309_electron" /> With parents potentially being convinced of the Electron's educational value, some reviewers foresaw a conflict between parents and "discerning children", the latter merely wanting to play games and preferring models with sound and graphics capabilities more appropriate for gaming.<ref name="popcompweekly19830825" />

Although Acorn had based its expansion into the United States on the BBC Micro, the company did have plans to introduce the Electron at a later time,<ref name="acornuser198311_us">{{ cite magazine | url=https://archive.org/details/AcornUser016-Nov83/page/n10/mode/1up | title=US quashes launch doubts | magazine=Acorn User | date=November 1983 | access-date=7 February 2022 | pages=7 }}</ref><ref name="electronuser198403_us">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-06/page/n8/mode/1up | title=US release next year? | magazine=Electron User | volume=1 | issue=6 | date=March 1984 | access-date=11 February 2022 | pages=9 }}</ref> with Chris Curry having indicated "a very heavy push overseas" involving both the BBC Micro and Electron.<ref name="practicalcomputing198210"/> A model for the US market was described in an official book, ''The Acorn Guide to the Electron'',<ref name="acornguide">{{ cite book | title=The Acorn Guide to the Electron | last1=Cryer | first1=Neil | last2=Cryer | first2=Pat | publisher=Penguin Books | isbn=0140078061 | date=1983 | oclc=64174269 }}</ref> but this model was never produced.<ref name="electronuser198502a" /> The Electron was distributed in various other markets and was reviewed by home computing publications in countries such as Norway,<ref name="hjemmedata198409">{{ cite magazine | url=https://archive.org/details/hjemmedata_09-1984/page/n5/mode/2up | title=Vi presenterer BBC jr. Electron | magazine=Hjemmedata | date=September 1984 | access-date=11 September 2024 | pages=6–7, 36–37 }}</ref> West Germany,<ref name="happycomputer198409">{{ cite magazine | url=https://archive.org/details/Happy.Computer.N11.1984.09-Cartman/page/n17/mode/2up | title=Very British, Indeed | magazine=Happy Computer | date=September 1984 | access-date=11 September 2024 | pages=18–22 }}</ref> and New Zealand.<ref name="bitsandbytes198404">{{ cite magazine | url=https://archive.org/details/nzbitsandbytes-2-07/page/n23/mode/2up | title=Cut-down BBC for about $800 | magazine=Bits & Bytes | last1=Forer | first1=Pip | date=April 1984 | access-date=11 September 2024 | pages=22–24 }}</ref>

===Production and volume delivery===
Production difficulties at [[Astec]] in Malaysia delayed the machine's introduction, forcing Acorn to look to other manufacturers such as AB Electronics in Wales and Wongs in Hong Kong (an [[original equipment manufacturer]] making over 30 million circuit boards a year, along with power supplies and plastic housings, for companies such as [[IBM]], [[Xerox]], [[Atari]], and [[Apple Inc.|Apple]], including units made for Acorn for the BBC Micro<ref name="popcompweekly19831201">{{ cite news | url=https://archive.org/details/popular-computing-weekly-1983-12-01/page/n14/mode/1up | title=Go east young man | work=Popular Computing Weekly | last1=Kelly | first1=David | date=1 December 1983 | access-date=30 March 2021 | page=15 }}</ref>). By October 1983, Acorn had received orders for more than 150,000 units, but had production targets of only 25,000 a month before Christmas, meaning that the existing backlog would take more than six months to fulfil. Demand for the Electron was high but only two of [[WH Smith]]'s London branches had inventory.<ref name="popcompweekly19831110">{{ cite news | url=https://archive.org/details/popular-computing-weekly-1983-11-10/mode/1up | title=Acorn shoots itself in foot | work=Popular Computing Weekly | date=10 November 1983 | access-date=30 December 2020 | pages=1, 5 }}</ref> Ultimately, manufacturing in Malaysia ceased with the anticipated but unspecified number of units having been produced,<ref name="electronuser198405a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-08/page/n7/mode/1up | title=No close-down | magazine=Electron User | date=May 1984 | access-date=14 January 2021 | page=8 }}</ref> this having been originally reported as 100,000 units.<ref name="electronuser198311a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-02/page/n2/mode/1up | title=Production rate is doubled | magazine=Electron User | volume=1 | issue=2 | date=November 1983 | access-date=20 January 2021 | page=3 }}</ref> Acorn's marketing manager, Tom Hohenberg, admitted in early 1984 that "a lot of the trouble stemmed from the ULA" in getting production to the desired levels,<ref name="electronuser198405">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-08/page/n6/mode/1up | title=Deliveries improve | magazine=Electron User | date=May 1984 | access-date=14 January 2021 | page=7 }}</ref> but that such difficulties had been resolved, although Acorn faced an order backlog of almost a quarter of a million units.<ref name="electronuser198404">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-07/page/n4/mode/1up | title=Production problems still dog Acorn | magazine=Electron User | date=April 1984 | access-date=14 January 2021 | page=5 }}</ref>

As the company increased production during 1984, however, the British home computer market greatly weakened. Hohenberg later noted that after the 1983 Christmas season, Electron deliveries had increased to meet a demand that was no longer there, with the market having "completely dried up".<ref name="retrogamer57">{{ cite news | url=https://archive.org/details/retro_gamer/RetroGamer_057/page/36/mode/2up | title=Retroinspection: Acorn Electron | work=Retro Gamer | issue=57 | last1=Goodwin | first1=Stuart | pages=36–41 }}</ref>{{rp|page=39|quote="We had this warehouse in Wellingborough," Hohenberg recalls. "Before Christmas, the trucks were lining up at one end wanting to take the few Electrons we had away to stores, but now the trucks were all at the other end, delivering, and the market had completely dried up. Seeing Electrons piled floor to ceiling... it was very depressing."}} Acorn's Christmas 1984 sales were greatly below expectations and by March 1985 the company had reduced the Electron's price to £129.<ref name="electronuser198503a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-06/page/n4/mode/1up | title=Acorn slashes price of Electron by £70 | magazine=Electron User | volume=2 | issue=6 | date=March 1985 | access-date=15 January 2021 | page=5 }}</ref> With the company's unsuccessful expansion into the United States abandoned,<ref name="electronuser198502a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-05/page/n6/mode/1up | title=American operation takes a £6m blow | magazine=Electron User | volume=2 | issue=5 | date=February 1985 | access-date=15 January 2021 | page=7 }}</ref> Acorn's financial situation had deteriorated sufficiently to prompt [[Olivetti]] to rescue the company by taking a 49.30% ownership stake.<ref name="electronuser198504">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-07/page/n4/mode/1up | title=New-look Acorn attacks on four fronts | magazine=Electron User | volume=2 | issue=7 | date=April 1985 | access-date=15 January 2021 | page=5 }}</ref> Renewed efforts were made to sell the machine, bundling it with Acorn's own expansions and software, such as one package adding the Plus 1 expansion, joysticks and a ROM cartridge game to the base machine for a total price of £219.<ref name="electronuser198504a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-07/page/n4/mode/1up | title=Electron not to be axed - and that is official | magazine=Electron User | volume=2 | issue=7 | date=April 1985 | access-date=15 January 2021 | page=5 }}</ref> Acorn committed to supporting the machine "until the end of 1986", continuing to supply it (as the Merlin M2105) to British Telecom as part of the Healthnet communications system, with small-scale manufacturing continuing while existing stocks were being run down.<ref name="acornuser198505a">{{ cite magazine | url=https://archive.org/details/AcornUser034-May85/page/n10/mode/1up | title=Electron marches on | magazine=Acorn User | date=May 1985 | access-date=23 January 2021 | page=9 }}</ref>

By autumn, retailers appeared eager to discount the computer, with prices in stores as low as £100, reportedly less than the distributor prices of the summer months.<ref name="electronuser198509">{{cite magazine| url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-12/page/n4/mode/1up | title=Great sale is on | magazine=Electron User | volume=2 | issue=12 | date=September 1985 | access-date=15 January 2021 | page=5 }}</ref> As the Christmas season approached, [[Dixons Retail]] acquired the remaining Electron inventory to sell, bundled with a [[cassette recorder]] and software, at a retail price of £99.95.<ref name="electronuser198511">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-02/page/n4/mode/1up | title=Dixons in pre-Xmas coup | magazine=Electron User | volume=3 | issue=2 | date=November 1985 | access-date=15 January 2021 | page=5 }}</ref> This deal, from the perspective of a year later, apparently played a significant part in helping to reduce Acorn's unsold inventory from a value of £18&nbsp;million to around £7.9&nbsp;million, and in combination with "streamlining corporate activities and reducing overheads", had helped to reduce Acorn's losses from over £20&nbsp;million to less than £3&nbsp;million.<ref name="electronuser198606_bacon">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-09/page/n4/mode/1up | title=Electron sales saved Acorn's bacon | magazine=Electron User | date=June 1986 | access-date=18 October 2021 | volume=3 | issue=9 | pages=5, 7 }}</ref>

The deal effectively brought to an end Acorn's interest in the Electron and the lower-cost end of the home computing market, but empowered third-party suppliers whose "inventiveness and initiative" was noted as being in contrast with Acorn's lack of interest in the product and the "false promises" made to its users.<ref name="electronuser198805mm">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-08/page/n54/mode/1up | title=The micro that outgrew Acorn | magazine=Electron User | volume=5 | issue=8 | date=May 1988 | access-date=23 January 2021 | last1=Dunkerley | first1=T. | pages=55–56 }}</ref> However, Acorn subsequently released the Master Compact{{snd}} a model in the [[BBC Master|Master series]] of microcomputers with fewer BBC Micro-style ports and a similar expansion connector to that used by the Electron{{snd}} with the home audience specifically in mind.<ref name="acornuser198610">{{cite magazine |url=https://archive.org/details/AcornUser051-Oct86/page/n7/mode/2up |magazine=Acorn User |title=Acorn gives birth to Master Compact |date=October 1986 |access-date=4 September 2020 |page=7 |quote=Acorn's philosophy is to aim the Compact at the home environment with parents buying a computer that their children can 'grow' into.}}</ref> Indeed, prior to its release, the Master Compact had been perceived as the successor to the Electron.<ref name="electronuser198609_brother">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-12/page/n4/mode/1up | title=Electron's big brother is due any day now | magazine=Electron User | volume=3 | issue=12 | date=September 1986 | access-date=17 January 2021 | page=5 }}</ref> Superficial similarities between the Compact and [[Acorn Communicator]], together with technical similarities between the Electron (particularly when expanded in the form of the Merlin M2105) and the Communicator, may also have driven rumours of an updated Electron model.<ref name="electronuser198606" /> A more substantial emphasis on the "home, music and hobby sectors" came with the appointment of a dedicated marketing manager in 1989 following the launch of the BBC A3000 in the [[Acorn Archimedes]] range.<ref name="acornuser198909">{{ cite magazine | url=https://archive.org/details/AcornUser085-Aug89/page/n10/mode/1up | title=New BBC home service | magazine=Acorn User | date=September 1989 | access-date=1 November 2020 | pages=7 }}</ref>

==Hardware==
Much of the core functionality of the BBC Micro{{snd}} the video and [[memory controller]], cassette input/output, timers and sound generation{{snd}} was replicated using a single customised ULA chip designed by Acorn in conjunction with [[Ferranti]], albeit with only one sound channel instead of three (and one noise channel), and without the character-based [[Teletext]] Mode 7.<ref name="smith20130823" />{{rp|page=1|quote=Out went the BBC’s 6845 video controller, memory controller, serial IO control and timer chips, all replicated to a greater or lesser extent by the ULA’s all-in-one circuitry. “We could pretty much fit all the functionality of the Beeb [BBC Micro] into a ULA with the exception of the microprocessor and the memory,” says Furber.}}

The keyboard includes a form of quick keyword input, similar to that used on the Sinclair [[ZX Spectrum]], through use of the {{keypress|FUNC}} key in combination with other keys labelled with BASIC keywords. However, unlike the Spectrum, this method of rapid keyword entry is optional, and keywords can be entered manually if preferred.<ref name="electronuser198311">{{cite magazine |url=https://archive.org/details/Electron_User_Vol._1_No._2_1983-11_Database_Publications_GB/page/n9/mode/2up |magazine=Electron User |title=Electron v. Spectrum |author=Peters, Nigel |date=November 1983 |access-date=3 September 2020 |pages=10–12}}</ref>

The [[edge connector]] on the rear of the Electron exposes all address and data bus lines from the CPU, including the upper eight bits of the address bus, in contrast to the limited selection available via the BBC Micro's expansion ports,<ref name="electronuser198310">{{cite magazine |url=https://archive.org/details/Electron_User_Vol._1_No._1_1983-10_Database_Publications_GB/page/n11/mode/1up |magazine=Electron User |author=Cook, Mike |title=Expanding Electron |date=October 1983 |access-date=3 September 2020 |page=12 |quote=the range of address bus signals available on the Electron edge connector is greater than is available on the BBC Micro with its collection of connectors and sockets.}}</ref> with the One Megahertz Bus as the principal mechanism for general purpose expansion on the BBC Micro only providing the lower eight bits of the address bus.<ref name="BAUG">{{cite book |last1=Bray |first1=Andrew C. |last2=Dickens |first2=Adrian C. |last3= Holmes |first3=Mark A. |date=1983 |title=The Advanced User Guide for the BBC Microcomputer |publisher=Cambridge Microcomputer Centre |page=437 |isbn=0946827001 |quote=A buffered databus and the lower 8 bits of the address bus are connected to this socket together with a series of useful control signals.}}</ref> In addition, various control signals provided by the CPU and ULA are exposed via the Electron's expansion connector.<ref name="EAUG">{{cite book |last1=Dickens |first1=Adrian C. |last2=Holmes |first2=Mark A. |date=September 1984 |title=The Advanced User Guide for the Acorn Electron |publisher=Adder Publishing, Cambridge |page=207 |isbn=0947929037 |quote=In fact, the Electron has more potential for expansion than a BBC Micro. Why? Because all necessary system buses come out on the expansion connector.}}</ref>

The ULA mediates access to 32&nbsp;KB of addressable RAM using four 4164 [[dynamic random-access memory|DRAMs]] (64&nbsp;K×1&nbsp;bit), sharing the RAM between the CPU and the video signal generation (or screen refresh) performed by the ULA itself. Two accesses have to be made to the RAM to get each byte (albeit with a single [[dynamic random-access memory#Page mode DRAM|RAS]]), delivering a maximum transfer rate to or from RAM of one byte per 2&nbsp;MHz cycle.<ref name="SM">{{cite book | url=http://chrisacorns.computinghistory.org.uk/docs/Acorn/Manuals/Acorn_ElectronSM.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://chrisacorns.computinghistory.org.uk/docs/Acorn/Manuals/Acorn_ElectronSM.pdf |archive-date=2022-10-09 |url-status=live|title=Electron Service Manual|publisher=Acorn Computers Limited|date=January 1987|issue=2|access-date=24 February 2019|page=7}}</ref> In generating the video signal, the ULA is able to take advantage of this 2&nbsp;MHz bandwidth when producing the picture for the high-bandwidth screen modes.<ref name="acornuser198309" />{{rp|page=26|quote=Now, 640 bits is 80 bytes of information, which means you have to get information out at the rate of 80/40 bytes per microsecond, or 2MHz.}} Due to signalling constraints, the CPU can only access RAM at 1&nbsp;MHz, even when it is not competing with the video system.<ref name="SM" />{{rp|page=7|quote=The processor will run at 1MHz during an access cycle to the RAM.}}

When the ULA is consuming all of the RAM bandwidth during the active portion of a display line, the CPU is unable to access the RAM. (The Electron uses the Synertek variant of the 6502 processor as that allowed the clock to be stopped for this 40 microsecond period.)<ref name="SM" />{{rp|page=7|quote=In screen modes 0, 1, 2 and 3 the screen uses all the available memory time slots during the display period. The processor is denied RAM access during 40 microseconds of each 64 microseconds of the 256 lines in 312 which is the display period, and it is made to wait for RAM access until the end of the period.}} In other modes the CPU and video accesses are interleaved with each accessor acquiring bytes at 1&nbsp;MHz.<ref name="SM" />{{rp|page=7|quote=The processor and the video are competing for access to the RAM, and the RAM can only support a bandwidth of 2&nbsp;MHz. In screen modes 4, 5 and 6 this is no problem since the screen only needs 1MHz access to the RAM.}}

In contrast, the [[BBC Micro]] employs one or two sets of eight 16-kilobit devices, with the RAM running at twice the speed (4&nbsp;MHz) of the CPU (2&nbsp;MHz), allowing the video system (screen refresh) and CPU memory accesses to be interleaved, with each accessor able to transfer bytes at 2&nbsp;MHz. The RAM access limitations imposed by the Electron's ULA therefore reduce the effective CPU speed by as much as a factor of four relative to the BBC Micro in the more demanding display modes, and as much as a factor of two otherwise. Byte transfers from ROM occur at 2&nbsp;MHz, however.<ref name="SM" />{{rp|page=7|quote=The processor will run at 2MHz during an access cycle to the ROM.}}

For issue 1–4 motherboards, the ULA had an issue similar to those experienced by other [[CPU socket|socketed]] CPUs. Over time, the thermal heating and cooling could cause the ULA to rise slightly out of its socket just enough to cause the machine to hang or freeze and for other issues to occur preventing the start-up of the machine, in some cases causing the initial beep or tone to sound continuously. This was despite a metal cover and a locking-bar mechanism designed to prevent this from occurring. Pushing down on the metal cover to reseat the ULA was normally sufficient to rectify these issues.{{Citation needed|date=March 2021}}<ref name="computerhistory">{{cite web |url=http://archive.computerhistory.org/resources/physical-object/acorn/102688877.lg.jpg |title=Image: 102688877.lg.jpg, (500 × 359 px) |publisher=archive.computerhistory.org |access-date=17 September 2015}}</ref><ref name="blogspot">{{cite web |url=http://3.bp.blogspot.com/-7zQebyfYlPE/T0dYrkTIIpI/AAAAAAAAAVY/injg8GeCoco/s1600/DSCF3052.JPG|title=Image: DSCF3052.JPG, (1600 × 1200 px) |publisher=3.bp.blogspot.com |access-date=17 September 2015}}</ref><ref name="blogspot2">{{cite web |url=http://1.bp.blogspot.com/-kyRwGNknHnU/T0dZHG8ThnI/AAAAAAAAAVo/JMFmxQLJstY/s1600/DSCF3055.JPG |title=Image: DSCF3055.JPG, (1600 × 1200 px) |publisher=1.bp.blogspot.com|access-date=17 September 2015}}</ref><ref name="bygonebytes">{{cite web |url=http://www.bygonebytes.co.uk/images/electron_issue4.jpg|title=Image: electron_issue4.jpg, (350 × 221 px) |publisher=bygonebytes.co.uk |access-date=17 September 2015}}</ref> Issue 5{{Citation needed|date=March 2021}} and 6 boards utilized a different ULA type, this being known as the Aberdeen ULA (as opposed to the earlier Ferranti ULA) which was mounted on a board that was directly soldered to the main board, with the chip being covered by epoxy resin "insulating material". This arrangement dispensed with the 68-pin socket, and this new type of ULA was expected to be "less prone to failure".<ref name="acorn_information_volume_1">{{ cite tech report | url=http://www.4corn.co.uk/archive/docs/Acorn%20Information%20-%20Volume%201-opt.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.4corn.co.uk/archive/docs/Acorn%20Information%20-%20Volume%201-opt.pdf |archive-date=2022-10-09 |url-status=live | title=Information Volume 1 | publisher=Acorn Computers Limited | date=October 1984 | access-date=21 March 2021 | page=246 }}</ref><ref name="bygonebytes2">{{cite web |url=http://www.bygonebytes.co.uk/images/electron_issue6.jpg|title=Image: electron_issue6.jpg, (350 × 220 px) |publisher=bygonebytes.co.uk |access-date=17 September 2015}}</ref> This type of ULA was also used on the German release of the Electron mainboard which is designated by the marking "GERMAN ELECTRON Issue 1" on the mainboard rather than just "ELECTRON" as for the UK model.<ref name="chris_german_electron">{{ cite web | title=German Acorn Electron | url=http://chrisacorns.computinghistory.org.uk/Computers/ElectronDe.html | date=2 May 2014 | access-date=15 January 2023 | website=Chris's Acorns }}</ref>

===Technical specifications===
[[File:Acorn ALF03 Data Recorder (top).jpg|thumb|Acorn ALF03 Data Recorder]]

The hardware specification according to official documentation,<ref name="amp020">{{ cite book | url=https://www.4corn.co.uk/archive/docs/AMPAPP/150/AMP020%20-%20electron-opt.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.4corn.co.uk/archive/docs/AMPAPP/150/AMP020%20-%20electron-opt.pdf |archive-date=2022-10-09 |url-status=live | title=Electron | publisher=Acorn Computers Limited | pages=5–8 }}</ref> combined with more technical documentation and analysis is as follows:

* [[central processing unit|CPU]]: [[Synertek]] [[6502|SY6502A]]<ref name="pastraiser">{{cite web|url=https://www.pastraiser.com/computers/acornelectron/acornelectron.html|title=Acorn Electron Hardware|publisher=pastraiser.com|access-date=17 September 2015}}</ref>
* [[Clock rate]]: variable. CPU runs at 2 [[megahertz|MHz]] when accessing ROM and 1&nbsp;MHz when accessing RAM. The CPU is also periodically halted.<ref name="SM" /><ref group=note>The Electron is widely misquoted as operating at 1.79&nbsp;MHz after measurements derived from speed testing against the 2&nbsp;MHz BBC Micro for various pieces of 'common software'.</ref>
* Glue logic: [[Ferranti|Ferranti Semiconductor]] Custom [[gate array|ULA]]
* [[random-access memory|RAM]]: 32 [[kilobyte|KB]]
* [[read-only memory|ROM]]: 32 [[kilobyte|KB]]
* Graphics modes: 160×256 pixels (20×32 characters) in 4 or 16 colours, 320×256 (40×32 characters) in 2 or 4 colours, 640×256 (80×32 characters) in 2 colours
* Text modes: 40×25 characters in 2 colours, 80×25 characters in 2 colours<ref group=note>Text modes are provided using display modes with the appropriate horizontal resolution (320 or 640 pixels), with each character row being 8 pixels high, and with 2 blank display lines being introduced between character rows.</ref>
* Colours: 8 colours (TTL combinations of RGB primaries) + 8 flashing versions of the same colours
* Sound: 1 channel of sound, 7 octaves; built-in speaker. Software emulation of noise channel supported
* Keyboard: 56 key "full travel QWERTY keyboard"<ref name="amp020" />
* Dimensions: 16×34×6.5&nbsp;cm
* I/O ports: Expansion port, tape recorder connector (1200 [[baud]] CUTS variation on the [[Kansas City standard]] for data encoding, via a 7-pin circular [[DIN connector]]), aerial TV connector ([[RF modulator]]), [[composite video]] and [[RGB]] monitor output
* Power supply: External PSU, 19&nbsp;[[volt|V]] [[alternating current|AC]]

The composite video output provides a [[greyscale image]] on the standard machine, but an internal modification allows a colour image to be produced, albeit with a degradation in picture quality. Acorn ostensibly intended the composite output to be a high-quality output for monochrome monitors, with the RGB output being the preferred high-quality output for colour images.<ref name="elbug198403_composite">{{ cite magazine | url=https://archive.org/details/elbug-v-01n-10/Elbug%20v01n04/page/16/mode/1up | title=Colour Video Output | magazine=ELBUG | date=March 1984 | access-date=9 August 2022 | volume=1 | issue=4 | pages=16 }}</ref>

===Merlin M2105===
An unusual variant of the Electron was sold by [[British Telecom]] Business Systems as the BT Merlin M2105 Communications Terminal, being previewed by British Telecom at the Communications '84 show.<ref name="acornuser198407_m2105">{{ cite magazine | url=https://archive.org/details/Acorn_User_1984-07_OCR/page/n10/mode/1up | title=Radio cell option for micros | magazine=Acorn User | date=July 1984 | access-date=18 March 2021 | page=9 | quote=British Telecom had the Healthnet terminal on show. This is an Electron with a custom-made expansion box, and it is intended for use where a lot of form-filling is done at many separate sites. }}</ref> This consisted of a rebadged Electron plus a large expansion unit containing 32&nbsp;KB of battery-backed RAM (making up 64&nbsp;KB of RAM in total), up to 64&nbsp;KB of ROM resident in four sockets (making up to 96&nbsp;KB of ROM in total), a [[Centronics printer port]], an RS423 serial port, a [[modem]], and the speech generator previously offered for the BBC Micro.<ref name="acornuser198406">{{cite magazine |url=https://archive.org/details/AcornUser023-Jun84/page/n8/mode/1up |magazine=Acorn User |title=Healthy link for Acorn |date=June 1984 |access-date=8 October 2020 |page=7}}</ref> The ROM [[firmware]] provided [[dial-up]] communications facilities, text editing and text messaging functions. The complete product included a monitor and dot-matrix printer.<ref name="electronuser198503" />

Initially trialled in a six-month pilot at 50 florists, with the intention of rolling out to all 2,500 members of the UK network,<ref name="electronuser198503">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-06/page/n4/mode/1up | title=Say it with Electron flowers! | magazine=Electron User | date=March 1985 | access-date=13 January 2021 | page=5 }}</ref> these were used by the [[Interflora]] florists network in the UK for over a decade.<ref>{{cite web |url=http://www.acornelectron.co.uk/eug/revs/bt/Merlin_M2105_002.html |title=Merlin M2105 | work=Acorn Electron World | publisher=Acornelectron.co.uk |access-date=12 January 2021}}</ref><ref name="chris_bt_m2105">{{cite web|url=http://chrisacorns.computinghistory.org.uk/Computers/BT_MerlinM2105.html |title=Chris's Acorns: BT Merlin M2105 |publisher=chrisacorns.computinghistory.org.uk |date=16 January 2008 |access-date=1 October 2015}}</ref> Used mostly for sending messages, despite providing support for other applications, limited availability of the product led Interflora to look for alternatives after five years, although users appeared to be happy with the product as it was.<ref name="electronuser198905a">{{cite magazine | url=https://archive.org/details/ElectronUserVolume6/Electron-User-06-08/page/n4/mode/1up | title=Flower folk like their Electrons | magazine=Electron User | date=May 1989 | access-date=11 November 2020 | page=5 }}</ref>

This generic product combination of the Electron and accompanying expansion was apparently known as the Chain during development,<ref name="acornuser198406" /> itself having a different board layout,<ref name="chain_m2105">{{ cite web | url=https://stardot.org.uk/forums/viewtopic.php?p=58667#p58667 | title=BT M2105 Version | website=stardot.org.uk | date=23 February 2013 | access-date=6 March 2021 }}</ref> with British Telecom having intended the M2105 to be a product supporting access to an online service known as Healthnet.<ref name="acornuser198406" /><ref name="acornuser198505">{{cite magazine |url=https://archive.org/details/AcornUser034-May85/page/n128/mode/1up |magazine=Acorn User |title=Acorn reviews ABCs |date=May 1985 |access-date=30 August 2020 |page=127}}</ref> This service aimed to improve and speed up communications within hospitals so that patients could be treated and discharged more quickly, and to facilitate transfers of information to doctors and health workers outside hospitals, with communications taking place over conventional telephone lines. The service was to be introduced in the Hammersmith and Fulham district health authority, with installation starting at Charing Cross Hospital. The Electron was said to be particularly suitable for deployment in this application in that it had a "large expansion bus",<ref name="electronuser198406">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-09/page/n6/mode/1up | title=Electron to speed up NHS communications | magazine=Electron User | date=June 1984 | access-date=14 January 2021 | page=7 }}</ref> ostensibly making the machine amenable to the necessary adaptations required for the role, together with its "price, and the fact it has a real keyboard".<ref name="electronuser198405b">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-08/page/n7/mode/1up | title=BT sign Electron boards contract | magazine=Electron User | date=May 1984 | access-date=14 January 2021 | page=8 }}</ref> As a Healthnet terminal, the M2105 was intended to support the exchange of forms, letters and memos.<ref name="btjournal198710">{{ cite journal | url=https://archive.org/details/btj-198710/page/n48/mode/1up | title=A prescription for healthy management | journal=British Telecom Journal | date=October 1987 | access-date=18 March 2021 | volume=8 | issue=3 | page=49 | quote=Healthnet is useful in hospitals and the National Health Service as a communications and information system. It transmits forms, letters and memos over the telephone as well as extracting data from the transmitted forms and turning it into clinical management information. Healthnet uses M2105 terminals. }}</ref>

The adoption of an Acorn product in this role was perhaps also unusual in that much of BT's Merlin range of this era had been supplied by ICL, notably the M2226 small business computer and M3300 "communicating [[word processor]]".<ref name="btjournal198307">{{ cite journal | url=https://archive.org/details/btj-198307/page/n67/mode/2up | title=Computer wizardry! | journal=British Telecom Journal | volume=4 | issue=2 | date=July 1983 | access-date=16 January 2021 | pages=34–35 }}</ref><ref name="bteng198307">{{ cite journal | url=https://archive.org/details/bte-198307/page/n73/mode/1up | title=First Electronics Office Products from Merlin | journal=British Telecommunications Engineering | date=July 1983 | access-date=26 February 2021 | volume=2 | issue=2 | page=132 | issn=0262-401X }}</ref> Nevertheless, the M2105 offered interoperability with other BT products such as the QWERTYphone which was able to receive messages from the M2105 and the [[One Per Desk|Merlin Tonto]].<ref name="bteng198701a">{{ cite journal | url=https://archive.org/details/bte-198701/page/n19/mode/2up | title=QWERTYphone - A Low-Cost Integrated Voice/Data Terminal | journal=British Telecommunications Engineering | last1=Durkin | first1=G. M. | date=January 1987 | access-date=26 February 2021 | volume=5 | issue=4 | pages=276–280 | issn=0262-401X }}</ref>{{rp|page=280|quote=Receives text messages from other QWERTYphones, Merlin Tonto and M2105 terminals or any terminal with a V.21 modem}}

The hardware specifications of the M2105, observed from manufactured units, include the 6502 CPU (SY6502<ref name="beebmaster_m2105">{{ cite web | url=http://www.beebmaster.co.uk/Elk/BTMerlin9.html | title=BT Merlin | website=BeebMaster | access-date=25 February 2021 }}</ref> or R6502), ULA and 32&nbsp;KB of dynamic RAM fitted in the Electron main unit, plus 32&nbsp;KB of static RAM, two 6522 VIA devices for interfacing, AM2910PC modem, SCN2681A [[UART]], and [[Texas Instruments LPC Speech Chips|TMS5220]] plus [[TMS6100]] for speech synthesis.<ref name="chris_bt_m2105" /> The speech synthesis was used for the "voice response" function which answered incoming voice calls by playing a synthesised message to the caller.<ref name="m2105_user_guide">{{ cite book | url=http://www.computinghistory.org.uk/det/10302/BT-Merlin-User-Guide-M2105-Messaging-Terminal/ | title=BT Merlin User Guide for M2105 Messaging Terminal | publisher=British Telecom Business Systems | date=June 1985 | volume=2 | pages=54, 78 }}</ref> The components chosen and the capabilities provided (excluding speech synthesis) are broadly similar to those featured by the [[Acorn Communicator]] which was another product of Acorn's custom systems division.

The product documentation indicates a specification with 48&nbsp;KB of RAM plus 16&nbsp;KB of "non volatile [[CMOS]] RAM" and 96&nbsp;KB of ROM,<ref name="m2105_user_guide" />{{rp|page=87}} although this particular composition of RAM is apparently contradicted by the RAM devices present on surviving M2105 machines.<ref name="chris_m2105_expansion">{{ cite web | url=http://chrisacorns.computinghistory.org.uk/Pics/BT_MerlinM2105LL.html | title=BT Merlin M2105 Expansion box circuitboard | website=Chris's Acorns | access-date=25 February 2021 }}</ref> However, the earlier Chain variant of the board does appear to provide only 16&nbsp;KB of static RAM using two HM6264LP-15 chips, also providing an extra 16&nbsp;KB of dynamic RAM using eight MK4516-15 chips, suggesting that the product evolved during development.<ref name="chain_m2105" />

===Recreations and emulators===
Several emulators of the machine exist:

# ElectrEm<ref>{{cite web |url=http://electrem.emuunlim.com |title=ElectrEm |publisher=Electrem.emuunlim.com |access-date=28 May 2013}}</ref> (Windows, Linux, Mac)
#Elkulator<ref>{{cite web|url=http://elkulator.acornelectron.co.uk |title=Elkulator - The Acorn Electron emulator |publisher=Elkulator.acornelectron.co.uk |access-date=28 May 2013}}</ref> (Windows, Linux)
#ElkJS<ref>{{cite web|url=http://elkjs.azurewebsites.net |title=ElkJS}} - JavaScript browser based Acorn Electron emulator</ref> is a browser-based emulator
#Multi-system emulators [[MESS]] and Clock Signal<ref>{{cite web |last1=Harte |first1=Thomas |title=Clock Signal |url=https://github.com/TomHarte/CLK |publisher=GitHub |access-date=31 March 2019}}</ref> support the Electron.

Electron software is predominantly archived in the [[UEF (file format)|UEF]] [[file format]].

There are also two publicly documented [[Field-programmable gate array|FPGA]] based recreations of the Acorn Electron hardware: ElectronFPGA<ref>{{cite web|url=https://github.com/hoglet67/ElectronFpga|title=ElectronFPGA|website=[[GitHub]] }}{{snd}} Acorn Electron core for the Papilio Duo</ref> for the Papilio Duo hardware and the Acorn-Electron<ref>{{cite web|url=http://www.fpgaarcade.com/kb/acorn-electron/|title=Acorn-Electron}}{{snd}} Acorn Electron core for the FPGA Arcade "Replay" board</ref> core for the FPGA Arcade "Replay" board. In addition, an implementation of the ULA for the [[ICE (FPGA)#iCE40 (40 nm)|Lattice ICE40]] series has been made available.<ref name="moogway82_ula">{{ cite web | url=https://github.com/moogway82/JamSoftElectronULA | title=JamSoftElectronULA | website=GitHub }}</ref>

==Software==
A range of titles were made available on cassette at the launch of the Electron through the [[Acornsoft]] publishing arm of Acorn, including a number of games, the [[Forth (programming language)|Forth]] and [[Lisp]] languages, and a handful of other educational and productivity titles.<ref name="acornuser198308_acornsoft"/> Acorn's decision to provide the Electron with a degree of compatibility with the BBC Micro meant that a number of titles already available for the older machine could be expected to run on its new machine, with only minor cosmetic issues occurring when running some titles. Of the Acornsoft languages, the existing Forth and Lisp language releases worked on the Electron, these being re-released specially for the machine, together with [[BCPL]] and Microtext, an authoring system offering programming facilities,<ref name="acornuser198410_microtext">{{ cite magazine | url=https://archive.org/details/AcornUser027-Oct84/page/n138/mode/1up | title=Framing the Right Questions | magazine=Acorn User | last1=Birnbaum | first1=Ian | date=October 1984 | access-date=19 January 2025 | pages=137, 139, 141 }}</ref> which remained BBC-only releases. Games such as Chess and [[Snooker]], plus a number of other titles were also established as being compatible prior to launch.<ref name="acorn_information_volume_1"/> Various applications in Acornsoft's View suite, together with the languages [[COMAL]], Logo and ISO [[Pascal (programming language)|Pascal]], were reported as being compatible with the Electron, as were some titles from BBC Soft and other developers.<ref name="electronuser198601_roms">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-04/page/n68/mode/1up | title=ROMs that work with Electron | magazine=Electron User | date=January 1986 | access-date=11 February 2023 | author=Slogger Advanced Systems | pages=69 }}</ref>

===Languages===
A significant selling point for the Electron was its built-in BBC BASIC interpreter, providing a degree of familiarity from the BBC Micro along with a level of compatibility with the earlier machine. However, as had been the case with the BBC Micro, support for other languages was quickly forthcoming, facilitated by the common heritage of the two systems.<ref name="acorn_information_volume_1"/>

In addition to the early releases, Forth and Lisp, Acornsoft released the Pascal subset, S-Pascal,<ref name="electronuser198503_pascal">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-06/page/n10/mode/1up | title=Try S-Pascal and get rid of those spaghetti junctions | magazine=Electron User | date=March 1985 | access-date=4 September 2022 | last1=Waddilove | first1=Roland | pages=11–12 }}</ref> on cassette and followed up with an ISO Pascal implementation on ROM cartridge,<ref name="electronuser198501_pascal">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-04/page/n4/mode/1up | title=BBC's Pascal for the Electron | magazine=Electron User | date=January 1985 | access-date=3 September 2022 | pages=5 }}</ref> the latter providing two 16&nbsp;KB ROMs containing a program editor and a Pascal compiler producing intermediate code that required Pascal run-time routines to be loaded.<ref name="acornuser198412_pascal">{{ cite magazine | url=https://archive.org/details/AcornUser029-Dec84/page/n179/mode/1up | title=Pascal Power | magazine=Acorn User | date=December 1984 | access-date=6 September 2022 | last1=Williams | first1=Simon | pages=176 }}</ref> As a more minimal implementation, S-Pascal made use of the machine's built-in BASIC program editing facilities and provided a compiler generating [[assembly language]] that would then be assembled, generating [[machine code]] for direct execution.<ref name="electronuser198503_pascal"/> ISO Pascal had Oxford Pascal as a direct competitor offering a range of features differentiating it from Acornsoft's product,<ref name="electronuser198503_oxford_pascal">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-06/page/n3/mode/1up | title=Oxford Pascal | magazine=Electron User | date=March 1985 | access-date=6 September 2022 | volume=2 | issue=6 | pages=4 }}</ref> notably a compiler that could produce a stand-alone "relocatable 6502 machine-code file".<ref name="acornuser198507_pascal">{{ cite magazine | url=https://archive.org/details/AcornUser036-Jul85/page/n66/mode/1up | title=Pleasures of Pascal | magazine=Acorn User | date=July 1985 | access-date=23 September 2022 | last1=Williams | first1=Simon | pages=65, 67, 69–70 }}</ref> Acornsoft later released the ISO Pascal Stand Alone Generator product for the BBC Micro and Master series, permitting the generation of executable programs embedding "sections of the interpreter" required by each program, with such executables being subject to various licensing restrictions.<ref name="acorn_app62a">{{cite book | title=A Choice of Programming Languages for the British Broadcasting Corporation Microcomputer System | url=http://chrisacorns.computinghistory.org.uk/docs/Acorn/Brochures/Acornsoft_APP62a_AcornsoftLanguages.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://chrisacorns.computinghistory.org.uk/docs/Acorn/Brochures/Acornsoft_APP62a_AcornsoftLanguages.pdf |archive-date=2022-10-09 |url-status=live | publisher=Acorn Computers Limited | access-date=29 September 2015}}</ref>

Acornsoft Forth, aiming for compliance with the Forth-79 standard, was regarded as "an excellent implementation of the language".<ref name="electronuser198410_forth">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-01/page/n54/mode/1up | title=Open up a whole new world with Forth | magazine=Electron User | date=October 1984 | access-date=6 September 2022 | last1=Waddilove | first1=Roland | pages=55 }}</ref> It saw competition from Skywave Software's Multi-Forth 83 which was delivered on a ROM chip, supported the Forth-83 standard, and provided a multitasking environment.<ref name="electronuser198410_multiforth83">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-01/page/n5/mode/1up | title=Go Forth and multitask! | magazine=Electron User | date=October 1984 | access-date=6 September 2022 | pages=6 }}</ref> Future availability of Multi-Forth 83 on ROM cartridge was advertised.<ref name="electronuser198410_skywave">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-01/page/n19/mode/1up | title=What the Acorn Electron has been waiting for! | magazine=Electron User | date=October 1984 | access-date=6 September 2022 | pages=20 }}</ref>

With the launch of the Plus 1, Acornsoft Lisp was also made available on cartridge.<ref name="electronuser198407p1" /> This Lisp implementation provided only the "bare essentials" of a Lisp system that "a small micro such as the Electron" could hope to be able to support. However, with the interpreter and initialised workspace being loaded from cassette into RAM in the earlier release, one stated advantage of the ROM version was the availability of more memory for use by programs, with the immediacy of a Lisp system provided as a language ROM being an implicit benefit.<ref name="electronuser198502_lisp">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-05/page/n11/mode/1up | title=Lisp, the language that strikes like lightning | magazine=Electron User | date=February 1985 | access-date=4 September 2022 | last1=Waddilove | first1=Roland | pages=12 }}</ref>

Acornsoft provided two products offering different degrees of support for the [[Logo (programming language)|Logo programming language]]. [[Turtle graphics|Turtle Graphics]] was a cassette-based product, available alongside Forth, Lisp and S-Pascal amongst the first titles released for the Electron,<ref name="acorn_amp18"/> featuring a subset of Logo focused on the interactive aspects of the language.<ref name="electronuser198710_logo">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-01/page/n41/mode/2up | title=Turtle graphics | magazine=Electron User | last1=Waddilove | first1=Roland | date=October 1987 | access-date=24 September 2022 | pages=42–43 }}</ref> Acornsoft Logo was provided on ROM cartridge and offered a vocabulary of over 200 commands as part of a more comprehensive implementation of the language, exposing its list processing foundations.<ref name="electronuser198711_logo">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-02/page/n36/mode/1up | title=Recursion and palindromes | magazine=Electron User | last1=Waddilove | first1=Roland | date=November 1987 | access-date=24 September 2022 | pages=42–43 }}</ref> Turtle Graphics was substantially cheaper than Logo: by 1987, the former had been reportedly discounted to under £3 whereas the latter cost "less than £30". Unlike other Acornsoft language products, however, Logo was supplied with "two thick manuals".<ref name="electronuser198710_logo"/>

===Applications===
Acornsoft made a number of applications available for the Electron. In early 1985, the ''View'' word processor and ''ViewSheet'' spreadsheet applications, familiar from the BBC Micro, were released on ROM cartridge for use with the Electron expanded with a Plus 1, priced at £49.50 each.<ref name="elbug198504_view">{{ cite magazine | url=https://archive.org/details/elbug-magazine-1985-04/page/n5/mode/2up | title=View and Viewsheet | magazine=ELBUG | last1=Otley | first1=David | pages=6–8 }}</ref> By running directly from ROM, these applications were able to dedicate all of the machine's available RAM to their documents, and using general filing system mechanisms, documents could be loaded from and saved to cassette or disc,<ref name="electronuser198510_view">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-01/page/n40/mode/1up | title=With a View to meatier output | magazine=Electron User | last1=Waddilove | first1=Roland | date=October 1985 | access-date=28 May 2023 | pages=41 }}</ref> although disc users could also use commands that took advantage of that faster, random-access medium.<ref name="electronuser198703_view">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-06/page/n23/mode/2up | title=Take a rom with a View... | magazine=Electron User | last1=Waddilove | first1=Roland | date=March 1987 | access-date=29 May 2023 | pages=24–26 }}</ref> Cassette-based operation was still regarded as "perfectly feasible" since the software itself did not need to be loaded, with loading and saving operations in View achieving about 800 words per minute and in ViewSheet achieving around 200 cells per minute.<ref name="elbug198504_view"/>

When using View in Mode 6, providing a 40-column, 25-line display occupying 8&nbsp;KB of memory, around 20&nbsp;KB of RAM was available to cassette-based systems or to disc-based systems using products such as the Cumana Floppy Disc System that also maintained PAGE at &E00,<ref name="electronuser198510_view"/> this corresponding to about 10 or 11 A4 pages of text. In Mode 3, providing an 80-column, 25-line display occupying 16&nbsp;KB, around 6 or 7 A4 pages of text could be retained in memory.<ref name="elbug198504_view"/> Acorn's Plus 3 disc system reduced this workspace by a further 4&nbsp;KB. However, documents could be broken up into sections to be processed individually by View. Operation in the 80-column Mode 0 and Mode 3 was reported as being "sometimes slow" due to the Electron's hardware architecture,<ref name="electronuser198510_view"/> but View supported horizontal scrolling across documents, permitting the use of a 40-column mode to edit wider documents.<ref name="elbug198504_view"/>

ViewSheet could also operate in different display modes, with spreadsheets of approximately 1600 cells being editable in Mode 6 and around 800 cells in Mode 3. A windowing system was provided that permitted ten different views of a spreadsheet to be displayed on screen at once, and recalculation operations were reported to be "around ten seconds for quite a large model". Reviewers considered the View and ViewSheet applications to be "professional" and to "compare well with similar software sold for much more expensive machines" such as the IBM PC,<ref name="elbug198504_view"/> with [[WordStar]] being noted as a broadly similar package to View.<ref name="electronuser198703_view"/> Compatibility with the same programs on the BBC Micro made a complete Electron-based system an attractive, low-cost, entry-level word processing and spreadsheet system.<ref name="elbug198504_view"/> However, View's printing support was criticised as inadequate without the use of a companion printer driver program.<ref name="electronuser198510_view"/>

Acornsoft did not release its ''ViewStore'' database program specifically for the Electron, but the software was reported as being compatible, albeit with function key combinations different to those documented for the BBC Micro.<ref name="electronuser198806_viewsheet_viewstore">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-09/page/n6/mode/1up | title=A dab-hand's view | magazine=Electron User | last1=Nixon | first1=Chris | date=June 1988 | access-date=9 June 2023 | pages=7–8 }}</ref> However, Acornsoft did release a product, ''Database'', on 3.5-inch diskette for use with the Electron upgraded with the Plus 3 expansion. The product provided a suite of programs for the creation, maintenance and analysis of structured data files, visualising records using a card index user interface metaphor, and supporting sorting and searching operations on the stored data.<ref name="electronuser198601_database">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-04/page/n10/mode/1up | title=Database | magazine=Electron User | last1=Bibby | first1=Pete | date=January 1986 | access-date=9 June 2023 | pages=11–14 }}</ref>

Slogger, an established provider of expansions, also produced productivity applications such as ''Starword'', a word processor, and ''Starstore'', a database. Starword provided separate command and editing modes familiar from Acornsoft's View, also supporting 132-column documents and horizontal scrolling for the editing of such wider documents. Along with other operations familiar from View, such as search and replace functions, block-based editing, and control over text justification, it had built-in support for customising documents for output using a [[mail merge]] function. Available on ROM for fitting to a ROM expansion such as Slogger's Rombox or inside a separately purchased ROM cartridge, and reportedly developed specifically for the Electron, Starword was considered "comprehensive and powerful".<ref name="electronuser198604_starword">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-07/page/n25/mode/1up | title=The WP system with some tricks up its sleeve | magazine=Electron User | last1=Richards | first1=David | date=April 1986 | access-date=9 June 2023 | pages=26 }}</ref>

Starstore, also available on ROM, provided a database management suite primarily aimed at users of cassette storage, with databases being entirely resident in RAM. It supported database definition, data editing, searching, sorting and printing activities. Various features complemented Starword, such as mail merge integration.<ref name="electronuser198609_starstore">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-12/page/n56/mode/1up | title=Making the most of your memory | magazine=Electron User | last1=Richards | first1=David | date=September 1986 | access-date=9 June 2023 | pages=57 }}</ref> ''Starstore II'' followed on as an alternative to, as opposed to a direct successor of, the earlier Starstore product by requiring a disc-based system and permitting databases to be as large as the amount of free space on any given disc. Its user interface was improved over the earlier product, offering pop-up menus and cursor-based navigation.<ref name="electronuser198611_starstore2">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-02/page/n20/mode/1up | title=Friendly – and foolproof | magazine=Electron User | last1=Richards | first1=David | date=November 1986 | access-date=9 June 2023 | pages=21 }}</ref>

Computer Concepts' ''Wordwise Plus'', developed from the company's earlier [[Wordwise]] product for the BBC Micro and launched in early 1985,<ref name="acornuser198502_wordwiseplus">{{ cite magazine | url=https://archive.org/details/AcornUser031-Feb85/page/n12/mode/1up | title=DIY command system boosts Wordwise chip | magazine=Acorn User | date=February 1985 | access-date=24 June 2023 | pages=11 }}</ref> was made available for use with the Electron expanded with the E2P-6502 second processor cartridge. The original Wordwise product was incompatible with the Electron due to its use of Mode 7 (the BBC Micro's 40-column Teletext display mode), and being supplied on a ROM chip, it could also not be readily added to the Electron without appropriate expansions. Available from Permanent Memory Systems, producers of the E2P-6502 cartridge, the Electron version of the software was the Hi-Wordwise Plus variant, supplied on disc instead of ROM, and designed to run on the second processor and to use the expanded memory provided in that environment. The program used the Electron's 40-column Mode 6 display.<ref name="electronuser198703_wordwiseplus"/>

Expansion manufacturers Advanced Computer Products and Slogger both made solutions available based on products from Advanced Memory Systems. ACP released a bundle of the ''AMX Mouse'' and ''AMX Art'' software for use with its Advanced Plus 5 expansion, also requiring a DFS-compatible disc system.<ref name="electronuser198704_amx">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-07/page/n21/mode/2up | title=Directing, doodling and designing | magazine=Electron User | last1=McLachlan | first1=Alan | date=April 1987 | access-date=25 June 2023 | pages=23 }}</ref> Slogger produced a version of the desktop publishing package ''Stop Press'' for the Electron, requiring a DFS-compatible disc system, two spare ROM sockets, a mouse, and a suitable user port expansion, with Slogger producing its own user port expansion cartridge.<ref name="electronuser198902_slogger"/> Competing with these products but requiring only a disc system, AVP's ''Pixel Perfect'' offered a rudimentary desktop publishing solution, utilising the computer's high-resolution Mode 0 display.<ref name="electronuser198902_pixelperfect">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume6/Electron-User-06-05/page/n23/mode/2up | title=Hold the front page! | magazine=Electron User | last1=Boswell | first1=Julie | date=February 1989 | access-date=25 June 2023 | pages=24–25 }}</ref>

===Games===
{{See also|List of Acorn Electron games}}

Of the twelve software titles announced by Acornsoft for the Electron at the machine's launch, six were games titles: ''[[Snapper (video game)|Snapper]]'', ''Monsters'' (a clone of [[Space Panic]]), ''Meteors'' (a clone of [[Asteroids (video game)|Asteroids]]), ''[[Starship Command]]'', ''Chess'', and the combined title ''Draughts and Reversi''.<ref name="acornuser198308_acornsoft">{{ cite magazine | url=https://archive.org/details/AcornUser013-Aug83/page/n7/mode/1up | title=Acornsoft will release 12 tapes for Electron | magazine=Acorn User | date=August 1983 | access-date=18 October 2021 | pages=6 }}</ref> When the Plus 1 expansion was launched in 1984, three of these titles{{snd}}''Hopper'', ''Snapper'' and ''Starship Command''{{snd}}were among the six ROM cartridge titles available at launch, together with the adventure ''Countdown to Doom''.<ref name="acornuser198406a" /> Acornsoft would continue to release games including those based on existing arcade games such as ''[[Arcadians (video game)|Arcadians]]'' (based on [[Galaxian]]) and ''Hopper'' (based on [[Frogger]]), as well as original titles such as ''Free Fall''<ref name="acorn_amp18">{{ cite book | url=http://chrisacorns.computinghistory.org.uk/docs/Acorn/Brochures/Acornsoft_AMP18_MasterpiecesForTheElectron.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://chrisacorns.computinghistory.org.uk/docs/Acorn/Brochures/Acornsoft_AMP18_MasterpiecesForTheElectron.pdf |archive-date=2022-10-09 |url-status=live | title=Masterpieces of Software from Acornsoft for the Electron | publisher=Acornsoft Limited | access-date=18 October 2021 }}</ref> and ''[[Elite (video game)|Elite]]''.<ref name="electronuser198411_elite">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-02/page/n6/mode/1up | title=Acornsoft launches new cult adventure | magazine=Electron User | date=November 1984 | access-date=18 October 2021 | pages=7 }}</ref>

[[Micro Power]], already an established BBC Micro games publisher, also entered the Electron market at a relatively early stage, offering ten initial titles either converted from the BBC Micro, in the case of ''Escape from Moonbase Alpha'' and ''Killer Gorilla'', or "completely re-written", in the case of ''Moonraider'' (due to differences in the screen handling between the machines).<ref name="electronuser198402_topten">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-05/page/n7/mode/1up | title='Top ten' take the lead | magazine=Electron User | date=February 1984 | access-date=18 October 2021 | volume=1 | issue=5 | pages=8 }}</ref> [[Superior Software]], also a significant publisher for the BBC Micro, routinely released games for both machines, notably a licensed version of Atari's [[Tempest (video game)|Tempest]] in 1985,<ref name="electronuser198505_tempest">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-08/page/n5/mode/1up | title=Electron Tempest hits new high spot | magazine=Electron User | date=May 1985 | access-date=18 October 2021 | volume=2 | issue=8 | pages=6 }}</ref> but also successful original titles such as the ''[[Repton (video game)|Repton]]'' series of games, ''Citadel'', ''[[Thrust (video game)|Thrust]]'' and ''[[Galaforce]]''. Superior's role in games publishing for the Acorn machines expanded in 1986 when the company acquired the right to use the Acornsoft brand, leading to the co-branding of games and compilations released by the company and the re-release of existing Acornsoft titles with this branding, Elite among them.<ref name="electronuser198609_superior_acornsoft">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-12/page/n5/mode/1up | title=Acorn-Superior software deal | magazine=Electron User | volume=3 | issue=12 | date=September 1986 | access-date=17 January 2021 | pages=6 }}</ref> The company would subsequently release another "masterpiece" with bundled novella{{snd}}the 1988 game ''[[Exile (1988 video game)|Exile]]''<ref name="electronuser198904_exile">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume6/Electron-User-06-07/page/n16/mode/1up | title=The new masterpiece | magazine=Electron User | last1=Revis | first1=Jon | date=April 1989 | access-date=18 October 2021 | volume=6 | issue=7 | pages=17–18 }}</ref>{{snd}}as well as numerous conversions and compilations.<ref name="electronuser199006_scott" />

By 1988, the "big three" full-price games publishers for the Acorn 8-bit market were identified as Superior Software, Audiogenic (ASL) and Tynesoft, with Top Ten and Alternative Software being the significant budget publishers, and other "strong contenders" being Godax, Mandarin and Bug Byte, this assessment made from the perspective of an established games author evaluating trustworthy publishers for aspiring authors. Commercial considerations motivated authors to make their games available for the Electron due to its importance in sales terms, representing "around half of the Acorn market", with it being regarded as "almost compulsory for any mainstream game" to have an Electron version "unless your game is a state-of-the-art masterpiece", with ''Revs'', ''Cholo'' and ''Sentinel'' cited as such BBC Micro exclusives.<ref name="diskuser198810_gameplan">{{ cite magazine | url=https://archive.org/details/DiskUser/Disk-User-12/page/n8/mode/1up | title=Game Plan | magazine=Disk User | last1=Scott | first1=Peter | date=October 1988 | access-date=21 October 2021 | pages=9–11 }}</ref> Although the Electron imposed additional technical constraints on authors accustomed to the BBC Micro, some authors were able to use this to their creative advantage. For instance, of ''Frak!'' it was noted that the "Electron version is more popular, and considered better than the BBC version because it has a screen designer included".<ref name="acornuser198812_allthebest">{{ cite magazine | url=https://archive.org/details/AcornUser077-Dec88/page/n144/mode/1up | title=All The Best | magazine=Acorn User | date=December 1988 | access-date=4 December 2021 | pages=143–145, 147–148 }}</ref>

[[File:CrystalCastles Electron.gif|thumb|''[[Crystal Castles (video game)|Crystal Castles]]'' is an example of an arcade game officially ported to the Electron by US Gold.]]

Although not as well supported by the biggest software publishers as rivals like the [[Commodore 64]] and Sinclair [[ZX Spectrum]], a good range of games were available for the Electron including popular multi-format games such as ''[[Chuckie Egg]]''. There were also many popular games officially converted to the Electron from arcade machines (including ''[[Crystal Castles (video game)|Crystal Castles]]'', ''[[Tempest (arcade game)|Tempest]]'', ''[[Commando (arcade game)|Commando]]'', ''[[Paperboy (video game)|Paperboy]]'', and ''[[Yie Ar Kung-Fu]]'') and other home computer systems (including ''[[Impossible Mission]]'', ''[[Jet Set Willy]]'', ''[[The Way of the Exploding Fist]]'', ''[[Tetris]]'', ''[[The Last Ninja]]'', ''[[Barbarian (computer game)|Barbarian]]'', ''[[Ballistix]]'', ''[[Predator (video game)|Predator]]'', ''[[Hostages (video game)|Hostages]]'' and ''[[SimCity (1989 video game)|SimCity]]'').<ref name="electronuser199006_scott" /><ref name="abcomputing198708_johnson">{{ cite news | url=https://archive.org/details/AB_Computing_1987-08_OCR/page/n34/mode/1up | title=Programmer Profile: Peter Johnson | work=A&B Computing | date=August 1987 | access-date=22 September 2021 | pages=35–36 }}</ref>

Despite Acorn themselves effectively shelving the Electron in 1985, games continued to be developed and released by professional software houses until the early 1990s.<ref name="electronuser199007a" /> There were around 1,400 games released for the Acorn Electron, several thousand extra public domain titles were released on disc through Public Domain libraries. Notable enterprises which produced discs of such software are BBC PD, EUG (Electron User Group) and [[HeadFirst PD]].{{citation needed|date=October 2021|reason=These figures and enterprises probably feature on a Web site somewhere, so it would be nice to see the source of such information.}}

===Development considerations and techniques===
[[File:ExileElectron.png|thumb|left|''[[Exile (1988 video game)|Exile]]'' is an example of a game where the developers left non-graphical data visible in the display buffer to gain additional memory space.]]
Like the [[BBC Micro]], the Electron is constrained by limited memory resources. Of the 32&nbsp;KB RAM, 3½ KB is allocated to the OS at startup and at least 10&nbsp;KB is taken up by the display buffer in contiguous display modes.

Although programs running on the BBC Micro can use the machine's [[MOS Technology 6522|6522]] chip to trigger interrupts at certain points in the update of each display frame, using these events to change the palette and potentially switching all colours to black, thus blanking regions of the screen and hiding non-graphical data that had been stored in screen memory, the Electron lacks such hardware capabilities as standard.<ref name="electronuser198801_blake" /> However, it was found to be possible to take advantage of the characteristics of interrupts that were provided, permitting palette changes after the top 100 lines of each display frame, thus facilitating the blanking of either the top 100 or bottom 156 lines of the display. Many games took advantage of this, gaining storage by leaving non-graphical data in the disabled area.<ref name="diskuser198810_gameplan" />{{rp|quote=You can use a colour interrupt to reduce the screen size by blanking out the top 13 or bottom 19 lines (other depths cause huge speed reductions).|pages=11}}<ref group=note>In this source, the "lines" appear to refer to character lines or multiples of 8 pixels, yielding 104 and 152 pixel lines respectively.</ref>

Other games would simply load non-graphical data into the display and leave it visible as regions of apparently randomly coloured pixels. One notable example is Superior Software's [[Citadel (video game)|Citadel]].<ref name="electronuser198602_danes">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-05/page/n7/mode/1up | title=Danes help produce new Electron titles | magazine=Electron User | date=February 1986 | access-date=16 October 2021 | volume=3 | issue=5 | pages=8 | quote="The program overspill appears as a fluctuating patterned strip at the bottom of the screen", said Payne, "It is the only way it could be released on the Electron". }}</ref>

Although [[page flipping]] is a hardware possibility, the limited memory forced most applications to do all their drawing directly to the visible screen, often resulting in graphical [[Flicker (screen)|flicker]] or visible redraw. A notable exception is [[Players (publisher)|Players]]' ''[[Joe Blade]]'' series.

A number of unusual techniques were employed by some developers to work around apparent limitations of the hardware.

====Firetrack: smooth vertical scrolling====
Although programs can alter the position of the screen in memory, the non-linear format of the display means that vertical scrolling can only be done in blocks of 8 pixels without further work.

''[[Firetrack]]'', released on a compilation by Superior Software,<ref name="electronuser198903_firetrack">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume6/Electron-User-06-06/page/n4/mode/1up | title=Firetrack speeds in for the Electron | magazine=Electron User | date=March 1989 | access-date=28 February 2021 | volume=6 | issue=6 | page=5 }}</ref> exploits a division in the way the Electron handles its display{{snd}} of the seven available graphics modes, two are configured so that the final two of every ten [[scanlines]] are blank and are not based on the contents of RAM. If 16 scanlines of continuous graphical data are written to a character-block-aligned portion of the screen then they will appear as a continuous block in most modes but in the two non-continuous modes they will be displayed as two blocks of eight scanlines, separated in the middle by two blank scanlines.

In order to keep track of its position within the display, the Electron maintains an internal display address counter. The same counter is used in both the continuous and non-continuous graphics modes and switching modes mid-frame does not cause any adjustment to the counter.

''Firetrack'' switches from a non-continuous to a continuous graphics mode part way down the display. By using the palette to mask the top area of the display and taking care about when it changes mode it can shift the continuous graphics at the bottom of the display down in two pixel increments because the internal display counter is not incremented on blank scanlines during non-continuous graphics modes.<ref name="firetrack">{{ cite web | url=http://electrem.emuunlim.com/techinfo.htm#firetrack | title=Vertical bipixel hardware scrolling | website=Acorn Electron Technical Documentation | date=15 August 2003 | archive-url=https://web.archive.org/web/20060206155259/http://electrem.emuunlim.com/techinfo.htm#firetrack | access-date=5 March 2021 | archive-date=6 February 2006 }}</ref>

====Exile: sampled speech====
''[[Exile (1988 video game)|Exile]]'' turns the Electron's one channel output into a digital speaker for [[pulse-code modulation|PCM]] output.

The speaker can be programmatically switched on or off at any time but is permanently attached to a hardware counter so is normally only able to output a [[Square wave (waveform)|square wave]]. But if set to a frequency outside the human audible range then the ear can't perceive the square wave, only the difference between the speaker being switched on and off. This gives the effect of a simple toggle speaker similar to that seen in the 48&nbsp;KB Sinclair [[ZX Spectrum]]. ''Exile'' uses this to output 1-bit audio samples.

====Frak! and Zalaga: polyphonic music====
As part of their [[copy protection]], illegal copies of Aardvark Software's ''[[Frak!]]'' and ''[[Galaga|Zalaga]]'' would cause a pseudo-polyphonic rendition of Trumpet Hornpipe, the [[Captain Pugwash]] theme tune, to play endlessly rather than loading the game properly (Pugwash being a pirate). On the Electron version of Frak!, the tune was the main theme from "[[The Benny Hill Show|Benny Hill]]" ([[Boots Randolph]]'s "[[Yakety Sax]]"). The [[polyphony]] was achieved via [[Arpeggio|fast note-switching]] to achieve the necessary chords.

==Hardware expansions==
{{Split section|date=October 2024}}

Since the Electron provides only a selection of video output ports, a cassette port and the expansion connector, a range of additional expansions were produced to offer ports and connections to various peripherals. The first expansions were largely joystick and printer interfaces or sideways ROM boards.<ref name="electronuser198406h">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-09/page/n7/mode/1up | title=Hardware galore! | magazine=Electron User | volume=1 | issue=9 | date=June 1984 | access-date=17 January 2021 | page=8 }}</ref> For instance, First Byte Computers developed an interface and software which allowed a "switched" joystick to be used with the majority of software titles.<ref name="electronuser198405c">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-08/page/n6/mode/1up | title=...and add-ons are on the increase, too | magazine=Electron User | volume=1 | issue=8 | date=May 1984 | access-date=20 January 2021 | page=7 }}</ref> This interface became very popular and was sold by W.H. Smiths, Boots, Comet and hundreds of independent computer dealers,{{Citation needed|date=January 2021|reason=The adverts do note distribution arrangements, but a good source would be nice.}} selling as many as 23,000 units over a two-year period, helped by a bundling agreement with Dixons.<ref name="electronuser198605fb">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-08/page/n4/mode/1up | title=Electron boom creates more jobs | magazine=Electron User | volume=3 | issue=8 | date=May 1986 | access-date=23 January 2021 | page=5 }}</ref>

Acorn's own expansion strategy was led by the Plus 1 which offered a combination of ports and cartridge connectors,<ref name="acornuser198502h">{{ cite magazine | url=https://archive.org/details/AcornUser031-Feb85/page/n48/mode/1up | title=Electron Extras | magazine=Acorn User | date=February 1985 | access-date=17 January 2021 | pages=47, 49, 51 }}</ref> followed by the Plus 3 disc drive unit, but by early 1986 the more general range of expansions had broadened to include floppy drive and RS423 interfaces, Teletext adapters, and other fundamental enhancements to the base machine.<ref name="electronuser198605h">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-08/page/n35/mode/2up | title=Hardware Survey | magazine=Electron User | volume=3 | issue=8 | date=May 1986 | access-date=17 January 2021 | pages=36–37 }}</ref>

===Multi-function expansions===
Since the Electron's expansion connector was the basis of practically all external hardware expansions for the machine, unless an expansion propagated this connector to others, as was done by the Acorn Plus 3, the capabilities of any given expansion would limit the capabilities of the expanded machine. Thus, expansions offering a single function, such as joystick ports or a printer port, would need to be disconnected if other capabilities were needed, and then reconnected later. Consequently, multi-function expansions offering a combination of different capabilities offered a significant degree of convenience as well as avoiding wear on the expansion connector.<ref name="electronuser198407exp">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-10/page/n7/mode/1up | title=Expansion bus 'no weak link' | magazine=Electron User | volume=1 | issue=10 | date=July 1984 | access-date=23 January 2021 | page=8 }}</ref>

Alongside announcements of Acorn's then-unreleased Plus 1,<ref name="electronuser198402acorn">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-05/page/n6/mode/1up | title=The expanding Electron - that's the next stage | magazine=Electron User | volume=1 | issue=5 | date=February 1984 | access-date=23 January 2021 | page=7 }}</ref> Solidisk previewed a General Purpose Interface for the Electron in early 1984 offering a Centronics printer port, switched joystick port, user port, sideways ROM sockets, and mini-cartridge sockets supported by the 6522 versatile interface adapter (VIA) chip.<ref name="electronuser198402gpi">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-05/page/n7/mode/1up | title=Piggyback interface for Electron | magazine=Electron User | volume=1 | issue=5 | date=February 1984 | access-date=23 January 2021 | page=8 }}</ref> The Plus 1 itself was released in mid-1984,<ref name="electronuser198407p1">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-10/page/n6/mode/1up | title=Expansion unit arrives - and it's official! | magazine=Electron User | volume=1 | issue=10 | date=July 1984 | access-date=23 January 2021 | page=7 }}</ref> introducing the influential cartridge format for expansions ultimately used by several other companies.

====Acorn Plus 1====
[[File:Acorn Electron and Plus 1.jpg|thumb|left|250px|An Acorn Electron with Plus 1 expansion unit attached]]
The Acorn Plus 1 added two ROM cartridge slots, an analogue interface (supporting four channels) and a [[IEEE 1284|Centronics parallel port]], priced at £59.90.<ref name="electronuser198407p1" /> The analogue interface was normally used for joysticks, although trackball<ref name="electronuser198510wh">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-01/page/n21/mode/1up | title=One way to have designs in the palm of your hand | magazine=Electron User | volume=3 | issue=1 | date=October 1985 | access-date=24 January 2021 | last1=Waddilove | first1=Roland | page=22 }}</ref> and graphics tablet<ref name="electronuser198603wh">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-06/page/n35/mode/1up | title=Try a tablet for pixel resolution | magazine=Electron User | volume=3 | issue=6 | date=March 1986 | access-date=24 January 2021 | last1=Nixon | first1=Robin | page=36 }}</ref> devices were available, and the parallel interface was typically used to connect a printer. Game ROM cartridges would boot automatically. Languages in paged ROM cartridges would take precedence over BASIC.<ref name="electronuser198409a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-12/page/n47/mode/1up | title=The Electron and the Plus 1 - made for each other | magazine=Electron User | date=September 1984 | access-date=14 January 2021 | page=48 }}</ref> (The slot at the front of the interface took priority if both were populated.)

Access to ROM occurs at 2&nbsp;MHz until RAM access is required, so theoretically programs released on ROM can run up to twice as fast as those released on tape or disc. Despite this, all of the games released on ROM were packaged as ROM filing system cartridges, from which the micro would load programs into main memory in exactly the same way as if it were loading from tape.<ref name="electronuser198411_rom">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-02/page/n22/mode/1up | title=Snappy ROM | magazine=Electron User | date=November 1984 | access-date=4 September 2022 | last1=Waddilove | first1=Roland | pages=23 }}</ref> This meant that programs did not need to be modified for their new memory location and could be written in BASIC but gave no execution speed benefits.<ref name="acornuser198407">{{cite magazine |url=https://archive.org/details/AcornUser024-Jul84/page/n19/mode/1up |title=Expansion Factor |magazine=Acorn User |date=July 1984 |access-date=24 October 2020 |last1=Smith |first1=Bruce |page=18 |quote=The filing system used by the ROM cartridge system is in fact the *ROM filing system (RFS) as used on the Beeb, making it a simple task for commercial establishments to blow their own cartridge ROMs. *CAT, LOAD and CHAIN are all available with the RFS.}}</ref> Six ROM cartridge titles were announced for the launch of the Plus 1: three arcade games, one adventure game, one educational title, and the ''[[Acornsoft LISP|Lisp]]'' language implementation,<ref name="acornuser198406a">{{cite magazine |url=https://archive.org/details/AcornUser023-Jun84/page/n10/mode/1up |title=Six-pack send-off for Electron ROM box |magazine=Acorn User |date=June 1984 |access-date=25 October 2020 |page=9}}</ref> the latter being a genuine language ROM that "takes the place of the BASIC ROM" and is instantly available when switching on.<ref name="acorn_amp031" />

The cartridge slots provide additional control lines (compared to the lines available via the edge connector on the rear of the Electron) to ease implementation of ROM cartridges.<ref>Electron Advanced User Guide{{snd}} Appendix E</ref> Acorn described the hardware extension possibilities in promotional literature, giving an RS423 cartridge as an example of this capability of the Plus 1.<ref name="acorn_amp031">{{ cite book | url=http://www.4corn.co.uk/archive/docs/AMPAPP/150/AMP031%20-%20electron%20plus%201-opt.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.4corn.co.uk/archive/docs/AMPAPP/150/AMP031%20-%20electron%20plus%201-opt.pdf |archive-date=2022-10-09 |url-status=live | title=Electron Plus 1: New Dimensions in Capability | publisher=Acorn Computers Limited | access-date=7 February 2021 }}</ref>

Additional peripheral cartridges were produced by companies such as Advanced Computer Products (and subsequently PRES) whose Advanced ROM Adaptor (ARA) and Advanced Sideways RAM (ASR) products provided [[Sideways address space|sideways ROM and RAM]] capabilities,<ref name="aeworld_acp">{{ cite web |url=http://www.acornelectron.co.uk/hardware/cats/acp_pres.html |title=Archive Catalogue Details: ACP/PRES |website=Acorn Electron World |access-date=6 March 2016  |archive-url=https://web.archive.org/web/20160306153913/http://www.acornelectron.co.uk/hardware/cats/acp_pres.html |archive-date=6 March 2016 |url-status=dead}}</ref>  allowing ROM- or EPROM-based software to be accessed to provide languages, utilities and applications.<ref name="electronuser198702_cartridges">{{ cite magazine | url=https://archive.org/details/ElectronUserVol4/Electron%20User%20%20Vol%204%20No.5/page/n59/mode/1up | title=Cartridge survey | magazine=Electron User | date=February 1987 | access-date=8 April 2022 | last1=Waddilove | first1=Roland | pages=60 }}</ref> ROM or EPROM devices containing the software could be physically inserted into empty [[Zero insertion force|ZIF]] sockets, or the software would be loaded from ROM image files (typically provided on disk) into RAM devices fitted in such sockets. Such RAM could potentially be powered by a battery and thus be able to retain its contents when the computer itself was powered off. Both such arrangements exposed the software in the same sideways memory region.<ref name="electronuser198706_acp_bbr">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-09/page/n36/mode/1up | title=Keep your memories fresh | magazine=Electron User | date=June 1987 | access-date=8 April 2022 | last1=Waddilove | first1=Roland | pages=37, 39 }}</ref>

Such cartridge support enabled the Electron to provide the same functionality as that offered by the expansion ROM slots under the keyboard and on the bottom-left of the BBC Micro B keyboard. However, the need to use cartridge sockets for other peripherals encouraged PRES to develop the Advanced Plus 6 (AP6): an internal RAM and ROM board for the Plus 1 providing six sockets that could be freely used for ROM, EPROM and RAM devices. Installation of the AP6 unit required some modifications to the Plus 1, undertaken either by the user or by PRES, and the product could also be enhanced with the Advanced Plus 7 offering battery-backed RAM support for two 16&nbsp;KB banks.<ref name="electronuser198805_ap6">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-08/page/n30/mode/1up | title=More room for your roms | magazine=Electron User | date=May 1988 | access-date=8 April 2022 | last1=Nixon | first1=Chris | pages=31 }}</ref>

The addition of the Plus 1 added a number of new *FX or OSBYTE calls that allowed the OS to read values from the analogue interface and write to the parallel interface.

The Plus 1 needed memory page &D for its workspace, and the unit added some processing overhead when enabled, both of these things causing issues with the loading and running of software, particularly cassette-based games. To disable the Plus 1, after pressing BREAK, the following commands could be issued:<ref name="electronuser198410p1">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-01/page/n60/mode/1up | title=Your Micro Power games and the Plus 1 | magazine=Electron User | volume=2 | issue=1 | date=October 1984 | access-date=24 January 2021 | page=61 }}</ref>

 *FX163,128,1
 ?&212=&D6
 ?&213=&F1
 ?&2AC=0

An official application note described a similar set of commands to "remove the Plus One completely from the address map disabling the Centronics and A/D ports (additionally disabling the RS423 cartridge if fitted)".<ref name="acorn_an013">{{ cite tech report | url=http://chrisacorns.computinghistory.org.uk/docs/Acorn/AN/013.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://chrisacorns.computinghistory.org.uk/docs/Acorn/AN/013.pdf |archive-date=2022-10-09 |url-status=live | title=Acorn Electron Plus One: Disabling the Centronics and A/D Port | publisher=Acorn Computers Limited | date=6 July 1992 | access-date=10 March 2021 | issue=1 | page=2 }}</ref>

=====Further developments=====

After Acorn's change of focus away from the Electron, and with a shortage of Plus 1 units available to purchase, Advanced Computer Products secured the rights to manufacture the unit under licence from Acorn,<ref name="abcomputing198708" /> obtaining the injection moulds and tooling, thus restarting production in 1987 after Acorn's own production of the unit had ceased in November 1985.<ref name="electronuser198703">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-06/page/n4/mode/1up | title=Plus 1 going back into production | magazine=Electron User | volume=4 | issue=6 | date=March 1987 | access-date=18 January 2021 | page=5 }}</ref> The Advanced Plus 2 (AP2) ROM was later sold by PRES as a replacement ROM for the Plus 1, of whose 8&nbsp;KB utility ROM only 3&nbsp;KB had been used, thus providing an opportunity for a more comprehensive ROM to be developed. The AP2 added ROM management commands familiar from the [[BBC Master]] series, support for various sideways RAM products from PRES, disc formatting and verification utilities for different ADFS versions, a command to disable the Plus 1 entirely, and improvements that made tape loading more reliable in "high memory" screen modes.<ref name="electronuser198807_ap2">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-10/page/n24/mode/1up | title=More power under your bonnet | magazine=Electron User | date=July 1988 | access-date=30 October 2022 | last1=Nixon | first1=Chris | pages=25 }}</ref>

====Slogger Rombox Plus====
Following on from Slogger's earlier Rombox product{{snd}} an expansion similar in profile to the Plus 1 but offering eight ROM sockets and propagating the expansion connector to other units<ref name="electronuser198508rombox">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-11/page/n52/mode/1up | title=Using all the Plus 1's slots? The Rombox gives you room for eight more ROMs | magazine=Electron User | volume=2 | issue=11 | date=August 1985 | access-date=23 January 2021 | last1=Waddilove | first1=Roland | page=53 }}</ref>{{snd}} the Rombox Plus was positioned more directly as a competitor to the Plus 1 in that it offered two cartridge slots and a Centronics print port alongside four ROM sockets. Priced at £49.95, the unit was mostly compatible with cartridges designed for the Plus 1 although one reviewer reported physical issues with some expansion cartridges, suggesting some manufacturing inconsistencies given other users' more positive experiences, but indicated that it was still "worth considering as an alternative to the Plus 1".<ref name="electronuser198611rombox">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-02/page/n54/mode/1up | title=Plug-in power: An alternative to the Plus 1 | magazine=Electron User | volume=4 | issue=2 | date=November 1986 | access-date=23 January 2021 | last1=Waddilove | first1=Roland | page=55 }}</ref> One review reported that the Cumana Electron Filing System cartridge had an edge connector that would not physically fit inside the slot in the Rombox Plus unit; this along with a perceived lack of robustness of the case being their only major reservations about the product. The product's support for utilising 8&nbsp;KB RAM devices as a printer buffer, with buffer management provided by the built-in EPROM, was noted as a particular advantage over the Plus 1.<ref name="abcomputing198610_dynamicduo">{{ cite magazine | title=Dynamic Duo | magazine=A&B Computing | last1=Fifield | first1=Matthew | last2=Webb | first2=Mark | date=October 1986 | pages=106–107 }}</ref>

====Slogger Remote Expansion and Plus 2====
In early 1989, Slogger announced its "remote expansion" (RX) system for the Electron, providing a separate case with power supply to house expansions and disc drives, able to support the weight of a monitor or television. Intended for the RX system, the Plus 2 offered two ROM cartridge slots compatible with the Plus 1, three ROM sockets, and RS423 and user port capabilities.<ref name="electronuser198901_slogger"/> One application of the user port was to connect a mouse, utilised by Slogger's version of the Stop Press desktop publishing package by Advanced Memory Systems.<ref name="electronuser198902_slogger">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume6/Electron-User-06-05/page/n46/mode/1up | title=A.M.S. Stop Press | magazine=Electron User | author=Slogger Limited | date=February 1989 | access-date=25 June 2023 | pages=47 }}</ref>

====Software Bargains Plus 1====
In mid-1989, Software Bargains announced an expansion providing different levels of Plus 1 functionality, offered as a bare printed circuit board without casing and in three different variants: the basic model offered one cartridge port and was bundled with View and Viewsheet cartridges for £29.95; an extended model offered one cartridge port and a printer port with the two bundled cartridges for £36.95; the full model offered two cartridge ports, printer port and the bundled cartridges for £39.95. Various board upgrade options were also offered between the variants, with the product being described mainly as a vehicle to expose the bundled software packages to as many as 150,000 owners of the estimated 200,000 Electrons in the UK who "have not yet been able to acquire or use View or Viewsheet".<ref name="electronuser198908sb">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume6/Electron-User-06-11/page/n4/mode/1up | title=Business boost for the Electron | magazine=Electron User | volume=6 | issue=11 | date=August 1989 | access-date=23 January 2021 | page=5 }}</ref> The lack of casing was considered the most significant disadvantage, with the absence of the analogue port deemed less critical due to a general lack of support for joysticks in many games.<ref name="electronuser198910_sb">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume7/Electron-User-07-01/page/n28/mode/1up | title=An offer you can't refuse | magazine=Electron User | date=October 1989 | access-date=28 October 2022 | last1=Waddilove | first1=Roland | pages=29 }}</ref>

===Communications and networking===
To support connectivity, Acorn announced a Plus 2 network interface with availability scheduled for early 1985, together with a RS423 cartridge for the Plus 1.<ref name="electronuser198411" /> Neither of these products were delivered as announced.

====Acorn Plus 2====
The Acorn Plus 2 interface was due to provide [[Econet]] capability.<ref name="acornuser198410">{{cite magazine |url=https://archive.org/details/AcornUser027-Oct84/page/n10/mode/1up |title=Electron gets microdrives in Plus 3 box |magazine=Acorn User |date=October 1984 |access-date=27 September 2020 |page=9}}</ref> This interface did not make it to market.<ref name="acornuser198606">{{cite magazine |url=https://archive.org/details/AcornUser047-Jun86/page/n46/mode/1up |title=Minus a Plus 2 |magazine=Acorn User |date=June 1986 |access-date=18 October 2020 |page=45}}</ref> However, an Econet interface was produced by Barson Computers in Australia<ref name="beebmaster_elknet">{{cite web |url=http://www.beebmaster.co.uk/Econet/ElkNet.html |title=Acorn Electron Econet Interface |work=BeebMaster |access-date=27 September 2020}}</ref> and possibly other individuals and businesses.<ref name="acornuser198606" />

====Acorn Plus 4====
The Acorn Plus 4 interface was due to provide a modem communications capability.<ref name="personalcomputernews198411">{{ cite news | url=https://archive.org/details/mag_PersonalComputerNews088-24Nov1984/page/n2/mode/1up | title=Electron wins its spurs | work=Personal Computer News | date=November 1984 | access-date=27 March 2021 | quote=The additions follow the style and numbering system of the Plus-1 printer, joystick and cartridge software interface. The disk system is the Plus-3, Econet comes with the Plus-2, and the modem connection will be the Plus-4. }}</ref>

====Andyk RS423 cartridge====
Andyk announced an RS423 cartridge for the Plus 1 providing a serial port, alongside other products, in late 1985. It was priced at £34.99.<ref name="electronuser198512" />

====Pace Tellstar/Nightingale====
Originally reported in mid-1985 as a collaboration between Acorn and Pace Micro Technology,<ref name="electronuser198508b">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-11/page/n4/mode/1up | title=Communications pack opens door to world | magazine=Electron User | volume=2 | issue=11 | date=August 1985 | access-date=16 January 2021 | page=5 }}</ref> but launched in early 1986, Pace offered a communications product consisting of a RS423 cartridge, bundled with a Nightingale modem and Tellstar communications software,<ref name="electronuser198602a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-05/page/n10/mode/1up | title=Electron shall speak unto Electron... | magazine=Electron User | volume=3 | issue=5 | date=February 1986 | access-date=15 January 2021 | pages=11–13 }}</ref> retailing at around £161 but discounted to £145.<ref name="electronuser198602b">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-05/page/n10/mode/1up | title=Now YOU - and your Electron - can enter the exciting, ever-changing world of telecomputing! | magazine=Electron User | volume=3 | issue=5 | date=February 1986 | access-date=15 January 2021 | page=55 }}</ref> The substantially reduced price of the Electron itself created an opportunity that Pace was "exploiting nicely" with its telecommunications bundle, described by one commentator as "a marvellous opportunity to get a cheap [[Prestel]] set in addition to your normal computer".<ref name="pcw198602_electron">{{ cite magazine | url=https://www.computinghistory.org.uk/det/1082/Personal-Computer-World-February-1986/ | title=Electron communications | magazine=Personal Computer World | last1=Kewney | first1=Guy | date=February 1986 | access-date=28 November 2024 | pages=84 }}</ref>

====Jafa Systems RS423 cartridge====
Jafa Systems announced an RS423 cartridge in late 1989 to "fill a two year gap in the market", offering a serial connector compatible with the BBC Micro together with an on-board socket for 8&nbsp;KB or 16&nbsp;KB EPROM devices or for 32&nbsp;KB RAM, the latter being configured to present two sideways RAM banks to the system. Write protect functionality was supported to prevent certain ROM software from attempting to overwrite itself if stored in RAM. The cartridge board itself was priced at around £30, with a case costing £5 extra, and an optional 32&nbsp;KB RAM adding another £20. Support for the E00 ADFS offered by PRES for that company's AP3 disc system was indicated as an application for the sideways RAM.<ref name="electronuser198911">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume7/Electron-User-07-02/page/n5/mode/1up | title=Add-ons boost for Electron | magazine=Electron User | volume=7 | issue=2 | date=November 1989 | access-date=21 January 2021 | page=6 }}</ref>

====Slogger Plus 2 RS423 interface====
Slogger provided an RS423 interface as an option for its own Plus 2 expansion, announced in early 1989.<ref name="electronuser198901_slogger">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume6/Electron-User-06-04/page/n4/mode/1up | title=Breakthrough boosts Electron's prospects | magazine=Electron User | date=January 1989 | access-date=21 November 2022 | pages=5 }}</ref>

===Disc interfaces===
The first disc interface to be announced for the Electron was Pace's Le Box in 1984, offering a single-sided 100&nbsp;KB floppy drive controlled by the 8271 controller and accessed using the Amcom Disc Filing System, with pricing at £299 plus VAT including the drive or around £199 without. The unit also provided eight sideways ROM sockets and was intended to sit under the Electron itself.<ref name="acornuser198409">{{ cite magazine | url=https://archive.org/details/AcornUser026-Sep84/page/n11/mode/1up | title=Pace first with drive link for Electron | magazine=Acorn User | date=September 1984 | access-date=13 January 2021 | page=10 }}</ref> The unit was connected via cabling to the expansion edge connector and included its own power supply, and other drives including switchable 40/80 track drives offering up to 400&nbsp;KB capacity were dealer-supplied options.<ref name="electronuser198410a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-01/page/n6/mode/1up | title=Le Box puts discs on tap | magazine=Electron User | date=October 1984 | access-date=13 January 2021 | page=7 }}</ref> Although the product was meant to be on sale at the Acorn User Show in August 1984,<ref name="acornuser198409" /> and had been advertised,<ref name="electronuser198409">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-12/page/n48/mode/1up | title=Le Box Electron Disc Interface | magazine=Electron User | date=September 1984 | access-date=14 January 2021 | page=49 }}</ref> it was "discontinued" in early 1985 before getting to market, with a Pace representative indicating that prohibitive pricing of the 8271 chips (each at "over £80 at times") had left the company considering a re-launch of the product should the pricing situation become more favourable.<ref name="acornuser198503">{{ cite magazine | url=https://archive.org/details/AcornUser032-Mar85/page/n10/mode/1up | title=New DFS in Plus 3 add-on for Electron | magazine=Acorn User | date=March 1985 | access-date=13 January 2021 | page=9 }}</ref>

Following on from Acorn's Plus 3 interface, [[Cumana (company)|Cumana]], Solidisk, Advanced Computer Products and Slogger all offered disc interfaces for the Electron. Unlike disc systems on the BBC Micro and the Acorn Plus 3, many of the systems released for the Electron did not claim RAM workspace (and raise the PAGE variable affecting applications above the default of &E00), making it easier to use cassette-based software transferred to disc and to run larger programs from disc.<ref name="electronuser198605c">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-08/page/n6/mode/1up | title=School plumps for mobile Electrons | magazine=Electron User | volume=3 | issue=8 | date=May 1986 | access-date=17 January 2021 | page=7 | quote="With PAGE the same as the tape system{{snd}} unlike the BBC DFS{{snd}} tape to disc transfer is easy..." }}</ref>

Low-cost alternatives to disc systems, briefly made fashionable by press coverage of the [[ZX Microdrive|Sinclair Microdrive]], were reportedly under development by expansion suppliers such as Solidisk,<ref name="electronuser198402gpi"/> and finished products such as the Phloopy [[Endless tape cartridge|looped tape]] system were offered for the Electron.<ref name="electronuser198501_phloopy">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-04/page/n5/mode/1up | title=Phloopy speeds the load | magazine=Electron User | date=January 1985 | access-date=13 February 2023 | pages=6 }}</ref> Reliability issues were described with the Phloopy, and the product was apparently short-lived.<ref name="electronuser199001_timewarp">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume7/Electron-User-07-04/page/n18/mode/1up | title=Time Warp 1985 | magazine=Electron User | last1=Woods | first1=Barry | date=January 1990 | access-date=13 February 2023 | pages=19 }}</ref>

====Acorn Plus 3====
[[File:Acorn ALA13 Electron Plus 3 (front).jpg|thumb|Acorn Plus 3, showing the connector and disc drive]]
Launched in late 1984 for a price of £229,<ref name="popcompweekly19841122">{{ cite news | url=https://archive.org/details/popular-computing-weekly-1984-11-22/page/n4/mode/1up | title=New Acorn products at Compec | work=Popular Computing Weekly | date=22 November 1984 | access-date=28 December 2020 | page=5 }}</ref> the Acorn Plus 3 was a hardware module that connected independently of the Plus 1 and provided a "self contained disc interface and 3.5 inch single sided disc drive" offering over 300&nbsp;KB of storage per disc using the newly introduced [[Advanced Disc Filing System]] (ADFS).<ref name="plus3">{{ cite book | url=http://www.4corn.co.uk/archive/docs/AMPAPP/150/AMP056%20-%20Electron%20Plus%203-opt.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.4corn.co.uk/archive/docs/AMPAPP/150/AMP056%20-%20Electron%20Plus%203-opt.pdf |archive-date=2022-10-09 |url-status=live | title=Electron Plus 3: New dimensions in capability | publisher=Acorn Computers Limited | page=2 }}</ref> The Plus 3 was also reportedly produced with a double-sided drive fitted.<ref name="electronuser198503_plus3">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-06/page/n34/mode/1up | title=...and then there was Plus 3 | magazine=Electron User | date=March 1985 | volume=2 | issue=6 | access-date=6 March 2021 | last1=Peters | first1=Nigel | page=35 | quote=Some versions of the Plus 3 allow both sides of the disc to be used, allowing 640k of information to be stored. }}</ref>

An expansion connector for a second 3.5- or 5.25-inch drive was also provided by the unit, with such drives needing to provide a [[Shugart bus|Shugart]]-compatible connector and their own power supply.<ref name="plus3ug">{{ cite book | url=http://chrisacorns.computinghistory.org.uk/docs/Acorn/Manuals/Acorn_Plus3UG.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://chrisacorns.computinghistory.org.uk/docs/Acorn/Manuals/Acorn_Plus3UG.pdf |archive-date=2022-10-09 |url-status=live | title=The Electron Plus 3 User Guide | publisher=Acorn Computers Limited | date=October 1984 | issue=1 | access-date=6 March 2021 }}</ref>{{rp|page=4}} The original Electron edge connector was repeated on the back of the Plus 3, allowing the Plus 1 or other compatible expansion to be connected in conjunction with the Plus 3.<ref name="plus3ug" />{{rp|page=5}}

The double-density drive of the Plus 3 was driven using a [[WD1770]] drive controller by the ADFS. (The Plus 3 had been rumoured to offer Acorn's DFS and to feature an 8272 double-density [[disk controller]] before its launch.<ref name="electronuser198411">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-02/page/n4/mode/1up | title=Electron disc drive - and it's official | magazine=Electron User | date=November 1984 | access-date=13 January 2021 | page=5 }}</ref>) Because the WD1770 is capable of single-density mode and uses the same IBM360-derived floppy disc format as the Intel 8271 found in the BBC Micro, it was also possible to use the [[Disc Filing System]] with an alternate ROM, such as the ACP 1770 DFS.<ref name="electronuser198602_acp1770dfs">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-05/page/n53/mode/1up | title=ROMs | magazine=Electron User | date=February 1986 | volume=3 | issue=5 | access-date=6 March 2021 | last1=Waddilove | first1=Roland | page=54 }}</ref>

The Plus 3 reset PAGE to &1D00, reducing the amount of free RAM available to the user.<ref name="plus3ug" />{{rp|page=52}} The ADFS system could be temporarily disabled (and PAGE reset to &E00) via the {{kbd|*NOADFS}} command.<ref name="plus3ug" />{{rp|page=15}} Later products such as the PRES E00 ADFS remedied the memory demands of the ADFS, along with other issues suffered by the software as delivered with the Plus 3.<ref name="electronuser198808" /> If using the Plus 3 in screen modes 0–3, the pseudo-variable {{mono|TIME}} would be thrown off, as the interrupts were disabled during disk access in these modes. The screen would also blank during disc accesses.<ref name="plus3ug" />{{rp|pages=14–15}}

Disks had to be manually [[Mount (computing)|mounted]] and dismounted using the {{kbd|*MOUNT}} / {{kbd|*DISMOUNT}} commands, or using the {{keypress|Ctrl}}+{{keypress|A}}+{{keypress|Break}} key combination. Disks could also be booted from via the standard {{keypress|Shift}}+{{keypress|Break}} key-combination, if the !BOOT file was present on the disk. This behaviour was the same as on the BBC Micro.<ref name="plus3ug" />{{rp|page=18}}

The Plus 3 included an uprated square black power supply unit with mains cord, manufactured by STC, designed and manufactured in England to {{nowrap|[[British Standards|BS]] 415}} and {{nowrap|BS 5850}}, that was designed to power the Plus 3, in addition to the Electron and the Plus 1 interface as well.<ref name="acorn_mains_adaptor">{{cite web | url=http://www.stardot.org.uk/forums/download/file.php?id=4417 | title=Plus 3 Disc Unit Mains Adaptor (36 watts) | date=4 October 1984 | issue=2 | access-date=14 March 2021 }}</ref> This replaced the original cream-coloured "wall wart" style power supply, designed to {{nowrap|BS 415}} and manufactured in Hong Kong.

* '''Original''' Part no: 0201,113;<ref name="acorn_do_0201">{{ cite tech report | url=http://www.4corn.co.uk/archive/do/registers/x201/0201.txt | title=0201 DETAIL DRAWINGS | publisher=Acorn Computers Limited | access-date=14 March 2021 }}</ref> input 220/240 V AC/50&nbsp;Hz; output 19 V AC/0.737 A/14 W:  '''Usage''': Electron, Electron+Plus1
* '''Uprated''' Part no: 0865,010; input 240&nbsp;V AC/50&nbsp;Hz 50&nbsp;W; output 21&nbsp;V AC/1.75&nbsp;A/36.75&nbsp;W: '''Usage''': Electron+Plus3, Electron+Plus3+Plus1

Repair note: If the internal power-supply connector, used to power the existing internal 3.5-inch drive is damaged, and requires replacement, then the original AMP 800-930 4-pin connector, which was already in short supply during the original production run, may be replaced with a Molex 5264 50-37-5043 "Mini-SPOX" connector as an alternative.<ref name="acorn_memo">{{cite tech report | url=http://www.stardot.org.uk/forums/download/file.php?id=4417 | title=Acorn Electron Disc Drive Connector{{snd}} Internal Memo | publisher=Acorn Computers Limited | last1=Ashby | first1=Simon | date=7 September 1984 | access-date=14 March 2021 }}</ref>

====Advanced Plus 3====
[[File:Advanced Plus 3.jpg|thumb|right|250px|The PRES Advanced Plus 3 with a 3½-inch drive]]
Designed and produced by Baildon Electronics and sold by PRES, the Advanced Plus 3 (AP3) was a Plus 1 cartridge interface using the WD1770 controller, supplied with Acorn's ADFS and a single-sided 3½-inch disc drive for £99 plus VAT, offering equivalent functionality to the Acorn Plus 3.<ref name="electronuser198710a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-01/page/n3/mode/1up | title=PRES announce Advanced Plus 3 | magazine=Electron User | volume=5 | issue=1 | date=October 1987 | access-date=20 January 2021 | page=4 }}</ref> Announced in late 1987, the product was made possible by an agreement between ACP and Acorn to license the ADFS software.<ref name="electronuser198710b">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-01/page/n3/mode/1up | title=Plus 3 upgrade | magazine=Electron User | volume=5 | issue=1 | date=October 1987 | access-date=20 January 2021 | page=5 }}</ref> As with many disc interfaces for the Electron, since the interface provided a connector for the drive, this made it possible to connect a 5¼" floppy disc drive (more common amongst BBC Micro owners) or the more typical 3½-inch drive.

PRES later released a version of ADFS with support for PAGE at &E00, this being achieved by using RAM provided by the Advanced Battery Backed RAM (ABR) cartridge. This version also fixed two notable bugs in Acorn's ADFS, eliminating unreliability when accessing the first tracks on a disc which had previously necessitated the writing of a file (ZYSYSHELP) as a workaround, and switching off the text cursor during disc compaction which had previously caused disc corruption (since the disc data would be processed using screen memory during this operation, and the cursor would modify that data when blinking). The ROM image was supplied on disc for £17.19, whereas a bundle of the ROM image and ABR cartridge was £50.95.<ref name="electronuser198808">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-11/page/n8/mode/1up | title=Improving on perfection | magazine=Electron User | volume=5 | issue=11 | date=August 1988 | access-date=20 January 2021 | last1=Waddilove | first1=Roland | page=9 }}</ref> A separate ADFS version 1.1 product, offered as a 16&nbsp;KB ROM, also provided these bug fixes. Advertised slightly earlier than the E00 ADFS,<ref name="electronuser198712_pres">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-03/page/n3/mode/1up | title=New Product ADFS E00 | magazine=Electron User | date=December 1987 | access-date=14 May 2025 | pages=4 }}</ref> it also replaced the Winchester hard drive support traditionally found in ADFS with "'patches' for future enhancements".<ref name="electronuser198711_pres">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-02/page/n3/mode/1up | title=New Product ADFS Version 1.1 for the Electron | magazine=Electron User | date=November 1987 | access-date=14 May 2025 | pages=4 }}</ref> Such patches, present in both of these ADFS variants, amounted to support for a 256&nbsp;KB RAM disc provided by the company's Advanced Quarter Meg RAM cartridge.<ref name="electronuser198807_pres">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-10/page/n33/mode/2up | title=PRES | magazine=Electron User | date=July 1988 | access-date=15 May 2025 | pages=34–35 }}</ref>

In 1989, the Advanced Plus 3 Mark 2 was launched, offering a double-sided drive in place of the single-sided drive previously offered. This meant that the storage capacity of each disc was increased from the 320&nbsp;KB of the original Plus 3 to 640&nbsp;KB (this being supported by ADFS on the Master Compact).<ref name="electronuser198905ap3">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume6/Electron-User-06-08/page/n4/mode/1up | title=It's the Plus 3+ | magazine=Electron User | volume=6 | issue=8 | date=May 1989 | access-date=21 January 2021 | pages=5 }}</ref> A "complete package" including double-sided, double-density floppy drive was advertised for just under £150 including VAT.<ref name="electronuser198905_pres">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume6/Electron-User-06-08/page/n41/mode/1up | title=The Advanced Plus 3 Mk II | magazine=Electron User | volume=6 | issue=8 | date=May 1989 | access-date=25 May 2025 | pages=42 }}</ref>

====Cumana Floppy Disc System====
Early in 1985,<ref name="electronuser198502">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-05/page/n5/mode/1up | title=Disc drive battle is joined | magazine=Electron User | date=February 1985 | access-date=13 January 2021 | page=6 }}</ref> Cumana released a cartridge-based interface providing support for double-density storage, a real-time clock and calendar for timestamping of files, and a spare ROM socket for user-fitted sideways ROMs.<ref name="cumana_disc_interface">{{ cite book | url=http://www.4corn.co.uk/archive/showpdfs/04%20Micro%20User-Electron%20User%20May%201985%20-%20Westminster/Cumana%20-%20electron%20disk%20drive%20interface.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.4corn.co.uk/archive/showpdfs/04%20Micro%20User-Electron%20User%20May%201985%20-%20Westminster/Cumana%20-%20electron%20disk%20drive%20interface.pdf |archive-date=2022-10-09 |url-status=live | title=Acorn Electron - Disc Drive Interface | publisher=Cumana Limited | date=March 1985 | access-date=21 March 2021 }}</ref> The filing system used was Cumana's own QFS, supporting 89 files per disc,<ref name="electronuser198507a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-10/page/n44/mode/1up | title=It's great being two-faced and twice as dense | magazine=Electron User | date=July 1985 | access-date=13 January 2021 | page=45 }}</ref> PAGE at &E00,<ref name="electronuser198605c" /> a non-hierarchical catalogue, ten-character filenames, with a format not directly compatible with either of Acorn's DFS or ADFS.<ref name="electronuser198507">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-10/page/n27/mode/1up | title=The Cumana floppy disc system for the Electron: It's an impressive piece of work | magazine=Electron User | date=July 1985 | access-date=13 January 2021 | last1=Peters | first1=Nigel | page=28 }}</ref> The interface itself cost £149.95 when originally announced,<ref name="electronuser198502" /> but settled at around £115.95 including VAT, also being offered in a promotional bundle with a 5¼-inch drive for £224.15 including VAT.<ref name="electronuser198507b">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-10/page/n51/mode/1up | title=Disc power at a new low price! | magazine=Electron User | date=July 1985 | access-date=13 January 2021 | page=52 }}</ref> Later pricing put the interface at £74.95 including VAT.<ref name="electronuser198601">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-04/page/n9/mode/1up | title=Electron Double Density Disk Interface Super Saver | magazine=Electron User | volume=3 | issue=4 | date=January 1986 | access-date=17 January 2021 | page=10 }}</ref>

====Solidisk EFS====
In mid-1985, Solidisk released a cartridge-based interface with support for single and double density storage and providing Acorn DFS and ADFS compatibility, 16&nbsp;KB of on-board sideways RAM, and a connector for a Winchester hard drive. The cartridge itself cost £59, with a bundle including a double-sided, double-density, 3½-inch drive costing £200.<ref name="electronuser198508">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-11/page/n5/mode/1up | title=Add-on for the Plus 1 | magazine=Electron User | date=August 1985 | access-date=13 January 2021 | page=6 }}</ref> A 20&nbsp;MB hard drive was offered at a price of £805. PAGE was set to &1900 when using the Solidisk system.<ref name="electronuser198508a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-11/page/n8/mode/2up | title=Solidisk EFS combines disc upgrade, 16K sideways RAM and a socket for the Winchester for only £59.00 | magazine=Electron User | date=August 1985 | access-date=13 January 2021 | pages=8–9 }}</ref>

====Advanced Plus 4====
Announced in early 1986,<ref name="electronuser198603ap4">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-06/page/n4/mode/1up | title=Interface opens up software range for Electron | magazine=Electron User | volume=3 | issue=6 | date=March 1986 | access-date=17 January 2021 | page=5 }}</ref> the Advanced Plus 4 (AP4) from Advanced Computer Products was a cartridge-based interface employing the WD1770 controller and featuring ACP's 1770 DFS product, providing compatibility with Acorn's DFS from the BBC Micro and thereby supporting seven-character filenames and up to 31 files per disc. However, 8&nbsp;KB of on-board static RAM was used as workspace for the filing system, keeping PAGE at &E00. An extra ROM socket was provided for a user-fitted sideways ROM, and being a 1770-based interface, it was reported that Acorn's ADFS could be used instead, although since it was not aware of the additional RAM, PAGE would be raised to &1D00 as it would be when using Acorn's Plus 3. The interface was priced at £69.55 plus VAT.<ref name="electronuser198606a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-09/page/n18/mode/1up | title=Disc drive compatibility at long last | magazine=Electron User | volume=3 | issue=9 | date=June 1986 | access-date=17 January 2021 | page=19 }}</ref>

====Slogger Electron Disc System and Pegasus 400====
Slogger, an established producer of expansions and a reseller of other disc systems, introduced the Electron Disc System in early 1987, priced at £74.95, featuring the Cumana Floppy Disc System interface,<ref name="electronuser198704a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-07/page/n13/mode/1up | title=New Release | magazine=Electron User | volume=4 | issue=7 | date=April 1987 | access-date=18 January 2021 | page=74 }}</ref> which was combined with an Acorn-compatible DFS, SEDFS, having the capability of reading 40-track discs on 80-track drives plus support for Slogger's tape-to-disc conversion products,<ref name="electronuser198704">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-07/page/n4/mode/1up | title=Disc power gives Electron a boost | magazine=Electron User | volume=4 | issue=7 | date=April 1987 | access-date=18 January 2021 | page=5 }}</ref> and reported as offering "virtual 100 per cent 8271 emulation" for compatibility with traditional DFS software.<ref name="electronuser198706">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-09/page/n55/mode/2up | title=DFS upgrade with BBC {{sic|compata|bility|nolink=y}} | magazine=Electron User | volume=5 | issue=9 | date=June 1987 | access-date=19 January 2021 | last1=Smiddy | first1=Mark | pages=56–57 }}</ref> The SEDFS ROM was also available separately for existing Cumana interface owners, priced at £24.95.<ref name="electronuser198704a" />

The SEDFS was later bundled with Slogger's own cartridge-based interface and a 40/80-track switchable drive offering up to 400&nbsp;KB storage per disc, with the bundle taking the Pegasus 400 name, introduced as part of a sales tour towards the end of 1987. This package of interface and drive cost £130.<ref name="electronuser198712">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-03/page/n5/mode/1up | title=Slogging around the country | magazine=Electron User | volume=5 | issue=3 | date=December 1987 | access-date=18 January 2021 | page=6 }}</ref> The precise DFS variant used by the Pegasus 400 system kept PAGE at &E00 and introduced "typeahead" support, permitting keystroke buffering during disc activity on systems with the Turbo-Driver or Master RAM Board fitted and enabled.<ref name="electronuser198901">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume6/Electron-User-06-04/page/n24/mode/1up | title=Driving hardware | magazine=Electron User | volume=6 | issue=4 | date=January 1989 | access-date=20 January 2021 | last1=Waddilove | first1=Roland | pages=25–26 }}</ref>

===Slogger/Elektuur Turbo boards===
Announced in early 1986, the Slogger Turbo-Driver was a professionally fitted upgrade priced at £42.<ref name="electronuser198602">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-05/page/n8/mode/1up | title=Upgrade 'boosts Electron's speed 100 per cent' | magazine=Electron User | volume=3 | issue=5 | date=February 1986 | access-date=15 January 2021 | page=9 }}</ref> The board itself plugged into the CPU and BASIC ROM sockets on the main circuit board of the Electron, which merely involved removing socketed components on very early Electron models, but required desoldering work and therefore benefited from a fitting service for later units. The performance benefit of fitting the board was to make some programs, particularly those running in the high bandwidth modes (0 to 3), run up to three times faster.<ref name="electronuser198607t">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-10/page/n21/mode/2up | title=Putting Electron into turbo-drive | magazine=Electron User | volume=3 | issue=10 | date=July 1986 | access-date=17 January 2021 | last1=Waddilove | first1=Roland | pages=22–23 }}</ref>

The direct origins of the Slogger product appear to be a board designed by Andyk Limited,<ref name="electronuser198607s">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-10/page/n23/mode/2up | title=The Elk Turbo-Driver | magazine=Electron User | volume=3 | issue=10 | date=July 1986 | access-date=17 January 2021 | page=24 }}</ref> announced as the Fast Electron Board in late 1985 with a price of £29.99,<ref name="electronuser198512">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-03/page/n8/mode/1up | title=New board gives Electron speed of BBC Micro | magazine=Electron User | volume=3 | issue=3 | date=December 1985 | access-date=17 January 2021 | page=9 }}</ref> whereas the Elektuur modification was described in an article in Dutch Electronics magazine Elektuur and intended for users to perform at home.<ref name="8bs">{{cite web|url=http://8bs.com/see/kupers_electron_6.jpg |title= kupers_electron_6 |publisher=8bs.com|access-date=17 September 2015}}</ref>

The Slogger and Elektuur Turbo boards were born out of a hack initially devised at Acorn. By shadowing the lowest 8&nbsp;KB of RAM with a static RAM chip outside of reach of the ULA, the CPU could always access it at 2&nbsp;MHz. The tradeoff was that the screen could not be located in that 8&nbsp;KB. In practice the operating system ROMs always put the screen into the top 20&nbsp;KB and as a result this probably only broke compatibility with around 2% of software.{{Citation needed|date=October 2021|reason=It would be nice to see the source giving Acorn as the origin of this design, also of the incompatibility figure which sounds like it originates in an article.}} Speeding up the low portion of memory is particularly useful on [[MOS 6502|6502]] derived machines because that processor has a faster [[zero page|addressing for the first 256 bytes]] and so it is common for software to put any variables involved in time-critical sections of program into that region.

The cost of the 64 Kbit [[Static random-access memory|SRAM]] chip would have been more than that of doubling the four 64 Kbit DRAM chips to give 8-bit RAM access, fixing both the modest memory and poor performance issues of the Electron. Retail pricing of HM6264-15 devices, one of these being used in the expansion,<ref name="8bs"/> was around ${{Format price|50|0}} in December 1983, in comparison to around ${{Format price|7|0}} for 150ns 4164 devices or ${{Format price|6|0}} for 200ns 4164 devices, four of the former thereby costing around ${{Format price|28|0}} in total. Thus, eight 4164 devices, at least at that time, would have cost ${{Format price|48|0}}-${{Format price|56|0}}, whereas a combination of four 4164 devices rated at 150ns together with a static RAM device would have cost around ${{Format price|78|0}}.<ref name="byte198312_jdr">{{ cite magazine | url=https://archive.org/details/byte-magazine-1983-12/page/n649/mode/1up | title=JDR Microdevices | magazine=Byte | date=December 1983 | access-date=8 August 2025 | pages=648 }}</ref>

===Slogger Master RAM Board===
Introduced at around the start of 1987 and priced at £64.95 fitted or £54.95 as a kit, the Master RAM Board offered the familiar turbo mode from the Slogger Turbo-Driver alongside a shadow mode providing 32&nbsp;KB of static RAM in addition to the existing 32&nbsp;KB dynamic RAM, thus giving 64&nbsp;KB in total RAM. Through the provision of 20&nbsp;KB of [[Shadow RAM (Acorn)|shadow RAM]], so-called "legally written software", this being software using the operating system calls and not writing directly to the screen, could function without significant modification, making substantially more memory available for BASIC, View, Viewsheet, language ROMs and many other applications.<ref name="electronuser198701">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-04/page/n58/mode/1up | title=Ramming home more memory | magazine=Electron User | volume=4 | issue=4 | date=January 1987 | access-date=18 January 2021 | last1=Pritchard | first1=Joe | pages=59–60 }}</ref> By providing extra storage this modification also allowed some games and applications intended for the BBC Micro to function on the Electron despite the lack of a native Mode 7.<ref name="andysarcade">{{cite web | title = Andy's guide to using BBC software on a 64K modified Acorn Electron. | url = http://www.andysarcade.net/personal/elk/64kmod/64kelectron.htm | access-date = 4 July 2008}}</ref> The RAM provided by the Master RAM Board was also "fast RAM", accessed by the CPU at 2&nbsp;MHz.<ref name="slogger_mrb">{{ cite book | url=https://acorn.huininga.nl/pub/mirrors/8bs.com/othrdnld/manuals/sloggermrbuser.zip | title=The Master RAM Board | publisher=Slogger }}</ref>

Applications could not directly address video memory in shadow mode without modification, so it was incompatible with most games, although there is no inherent reason why a game could not be written to function in shadow mode. A switch mounted through the case switched between normal, turbo and shadow modes. Despite providing an extra 32&nbsp;KB, shadow mode potentially left up to 12&nbsp;KB of the Electron's original dynamic RAM unused, with limited initial support provided for the use of this lower memory region.<ref name="acornuser198704">{{ cite magazine | url=https://archive.org/details/AcornUser057-Apr87/page/n147/mode/2up | title=Slogging it out | author=Emblem, Bernard | magazine=Acorn User | date=April 1987 | access-date=29 August 2020 | pages=146–147 }}</ref> However, Slogger's modified operating system provided fundamental support for its use as a "print buffer",<ref name="slogger_mrb"/> utilised by the company's own printer buffer software, and the programming interface concerned was elucidated in a series of magazine articles.<ref name="electronuser198804_shadows">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-07/page/n44/mode/1up | title=Staying in the Shadows | magazine=Electron User | volume=5 | issue=6 | date=April 1988 | access-date=5 May 2025 | last1=Nixon | first1=Chris | pages=45–46 }}</ref>

Towards the end of the Electron's commercial lifetime, the Turbo-Driver and Master RAM Boards were offered already fitted to new Electrons in an attempt to increase sales. For a time, Jafa Systems manufactured their own equivalent of the Master RAM Board in order to support their own product range.<ref name="andysarcade" />

===Mode 7 display expansions===
One of the features of the BBC Micro that was absent in the Electron was the [[Teletext]]-style ''Mode 7'' display. The omission of this display mode was remarkable because it had a very low memory requirement (just 1000 bytes) and many BBC programs used it to maximise available memory for program code and data while also providing a colourful 40-column textual display with simple low-resolution graphical decorations.<ref name="abcomputing198610">{{ cite news | url=https://archive.org/details/AB_Computing_1986-10_OCR/page/n89/mode/2up | title=Channel 7 | work=A&B Computing | date=October 1986 | access-date=9 November 2020 | last1=Waugh | first1=Ian | pages=90–91 }}</ref>{{rp|page=90|quote=The BBCs Mode 7 uses a teletext display, tt is produced by a special teletext chip which leaves most of the Beeb’s 32K memory free for programs. Graphic displays in Mode 7 are created differently to the displays in the so-called graphic Modes. Teletext graphics characters use a 2x3 grid the same size as an alphanumeric character which gives them a rather chunky look.}}

Such display capabilities, desirable in their own right on low-memory computers, were also desirable for delivering content through low-bandwidth communications channels such as that from Teletext and [[Viewdata]] services. However, access to such services can be considered to be a separate capability, and the BBC Micro needed to be upgraded to complement its display capability with the Teletext or [[Prestel]] adapters to receive such over-the-air or online content.<ref name="abcomputing198610" />{{rp|page=90|quote=you only need a few more bits and bobs (and chips, etc.) to turn the Beeb into a teletext receiver. The Morley Adapter does just that.}}

Jafa Systems provided a number of solutions to remedy the absence of a Teletext display capability. Morley Electronics instead chose to offer an expansion combining the display and reception capabilities.

====Sir Computers====
In late 1984, Sir Computers announced a Mode 7 adapter unit that plugged into the Electron's expansion connector.<ref name="electronuser198410">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-01/page/n5/mode/1up | title=Mode 7 for the Electron | magazine=Electron User | date=October 1984 | access-date=13 January 2021 | page=6 }}</ref> Unfortunately, Sir Computers ceased trading before the product was brought to market.<ref name="electronuser198607">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-10/page/n47/mode/1up | title=Teletext adapter | magazine=Electron User | date=July 1986 | access-date=13 January 2021 | page=48 }}</ref>

====Jafa Systems====
Released in 1987 at a price of £89,<ref name="electronuser198907">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume6/Electron-User-06-10/page/n17/mode/2up | title=One man band | magazine=Electron User | date=July 1989 | access-date=10 November 2020 | last1=Leah | first1=Tony | pages=18–19 }}</ref> the Mode 7 Mark 1 Display Unit was a separate unit "about the size, shape and colour of the Plus One or a Slogger ROMbox"<ref name="acornuser198805_jafa">{{ cite magazine | url=https://archive.org/details/AcornUser070-May88/page/n154/mode/1up | title=Electron a la Mode | magazine=Acorn User | date=May 1988 | access-date=17 April 2021 | last1=Emblem | first1=Bernard | pages=153 }}</ref> that connected to the Electron's expansion connector and featured a [[Motorola 6845]] display controller and [[Mullard SAA5050]] character generator to replicate the main elements of the BBC Micro's Teletext display solution. This only used 1&nbsp;KB of memory for the display, with the expansion listening to display memory write accesses and buffering the data in its own memory.<ref group=note>Here, [https://git.redump.net/mame/tree/src/devices/bus/electron/mode7.cpp the MAME source code emulating the Mark 1 adapter] is informative.</ref> A ROM was included to extend the operating system to allow activation of Mode 7 as a genuine screen mode and to provide extra commands and to support keyboard shortcuts used on the BBC Micro to emit Teletext control sequences. To support the output of both the Mode 7 display and the existing video output, a lead connected the Electron's RGB output to the expansion, with the expansion providing only RF (television) output.<ref name="electronuser198708">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-11/page/n19/mode/1up | title=Teletext on tap | magazine=Electron User | date=August 1987 | access-date=10 November 2020 | last1=Waddilove | first1=Roland | page=20 }}</ref>

Conscious of the relatively high price of the Mark 1 unit,<ref name="electronuser198907" />{{rp|page=19|quote=Interestingly, when it came out the Mode 7 Adaptor at £85 cost nearly twice as much as the Electron was going for in many places under the heading of obsolete stock. Because of this at the end of last year John decided to produce a £25 simulator including a Mode 7 screen editor program.}} John Wike of Jafa devised and, at the end of 1988, introduced a software-based ''Mode 7 Simulator'', priced at £25, supplied on a ROM cartridge that rendered the Mode 7 display in a low-resolution, 8-colour graphics mode. Although cheap and effective in enabling use of some software that only used official operating system routines for text output, this solution proved very slow because the Electron had to be placed into the high-bandwidth Mode 2 display to be able to show eight colours at once. In doing so, the CPU spent a lot of time drawing representations of Mode 7 characters and graphics that in a hardware solution would be achieved without any demand on the CPU. It also used up 20&nbsp;KB of RAM for the graphics display rather than the 1000 bytes of a hardware Mode 7.<ref name="electronuser198905">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume6/Electron-User-06-08/page/n36/mode/1up | title=The software solution | magazine=Electron User | date=May 1989 | access-date=9 November 2020 | last1=Cusack | first1=Stephen | pages=37–38 }}</ref>

A conceptually similar predecessor to the software-based simulator was published by Electron User in early 1987, offering a monochrome Mode 4 simulation of the Teletext display, using the lower 25 character lines of the screen to show the Teletext output, reserving several lines at the top of the screen for a representation of Mode 7 used to prepare the eventual visual output. However, the program did not support direct access to Mode 7 memory locations. The author noted that a Mode 2 version would have been possible but would have required a redesigned character set and "too much memory".<ref name="electronuser198701m7">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-04/page/n25/mode/2up | title=Go Mode 7 the software way | magazine=Electron User | volume=4 | issue=4 | date=January 1987 | access-date=19 January 2021 | last1=Nixon | first1=Robin | pages=26–27 }}</ref>

A further refinement of the hardware solution was introduced in 1989 with the Mode 7 Mark 2 Display Unit, which retained the SAA5050 character generator but omitted the 6845 display controller, and was fitted internally in the Electron itself instead of being housed in an external unit, although some kind of ROM expansion unit was needed to hold the driver/utilities ROM. It used software to ensure that the SAA5050 was fed with the correct character data. A software ROM would put the machine into a two-colour, 40-column graphics mode (thus providing one byte per character), and as the ULA read display data from memory in the usual fashion, the SAA5050 would listen to the data it was reading and produce a Mode 7 interpretation of the same information,<ref name="jafamk2">{{ cite book | url=http://www.bygonebytes.co.uk/images/Mode7Manual.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.bygonebytes.co.uk/images/Mode7Manual.pdf |archive-date=2022-10-09 |url-status=live | title=Jafa Systems User Guide for the Mode 7 Mk 2 Display Unit | publisher=JAFA Systems | date=1989 | access-date=10 November 2020 }}</ref>{{rp|page=3}} this being achieved by fitting a board on top of the ULA connecting to its pins.<ref name="jafamk2" />{{rp|page=20|quote=Take the smaller of the Mode 7 Mk2 boards and lay it on the under side of the Electron board so that the holes in it fit over the pins of the ULA.}} When necessary the hardware would switch between the conventional Electron graphics output and the Mode 7 output being produced by the add-on, feeding it to the Electron's built-in video output sockets via the red, green and blue lines on the motherboard.<ref name="jafamk2" />{{rp|page=22|quote=The diagram on page 16 shows 4 pads around IC3 marked R, G, B and Sy. These now need to be wired to the similarly labelled points on page 18.}}

The disadvantage to this system is that while the SAA5050 would expect to be repeatedly fed the same 40 bytes of data for every display scanline of each character row, the ULA would read a different set of 40 bytes for every display scanline in order to produce a full graphics display. A software ROM worked around this by duplicating the data intended for a Mode 7 display in memory. Although this produced a Mode 7 that had less of an impact upon CPU performance than a software solution, gave the same visual quality as the BBC Micro, and supported direct access to Mode 7 screen addresses as well as accesses via operating system routines, it still used 10&nbsp;KB of memory for the display and reduced the amount of readily-usable application memory  (as indicated by HIMEM) by another 6&nbsp;KB.<ref name="jafamk2" />{{rp|pages=3–4|quote=The other, between &4000 and &6800, is the Mode 4 display area that is actually scanned by the Mode 7 Mk2 circuits.}}

However, with users increasingly able to rely on expansions such as the Slogger Master RAM board to provide more memory, and with this combination of expansions acknowledged throughout the user manual, the emphasis of the Mode 7 Simulator and Mark 2 Display Unit was arguably to deliver the actual display capabilities for those applications that needed them, instead of using Mode 7 as a way of economising with regard to memory usage, and to do so at a reasonable price. In this latter regard, the Mark 2 model was available as a kit costing £25 or as an assembled product (requiring some soldering) costing £49, with a fitting service available for £10.<ref name="electronuser1989">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume7/Electron-User-07-02/page/n5/mode/1up | title=Add-ons boost for Electron | magazine=Electron User | date=November 1989 | access-date=11 November 2020 | page=6 }}</ref>

The Jafa interfaces did not provide a Teletext or Viewdata reception capability, but the Mark 2 was explicitly stated to work in conjunction with the Morley Electronics Teletext Adapter.<ref name="jafamk2" />{{rp|page=15|quote=To receive TELETEXT you will require a Master RAM board, a User Port and a Morley Teletext Adapter with separate power supply.}} Meanwhile, the manual for the Mark 2 noted that the product would provide the functionality of a Viewdata terminal if combined with Jafa's RS423 cartridge.<ref name="jafamk2" />{{rp|page=2|quote=If you use the socket in the JAFA Systems RS423 cartridge then you will have a self-contained PRESTEL terminal.}}

====Morley Electronics====
Morley Electronics produced a Teletext Adaptor expansion for the BBC Micro and the Electron. Since the BBC Micro has the Mode 7 display capability, the model aimed at the BBC Micro merely provided the content reception capability needed to receive and decode Teletext signals, connecting to the user port and power supply. However, the Electron models provided both display and reception capabilities, doing so by routing either the RGB or UHF signals (depending on the model) through the unit in order to introduce the Mode 7 output produced by the unit, also connecting via a cartridge. The Teletext display capabilities in the Electron models exceeded those of the BBC Micro, with one reviewer noting that the enhanced capabilities permitted "black text on a coloured background, something I've always wanted to do on my Beeb".<ref name="abcomputing198610" />{{rp|page=90}} The UHF model of the Electron adapter also supported overlaying of Teletext onto video and framing of video.<ref name="abcomputing198610" />{{rp|page=91}}

===Second Processor expansions===
Acorn did demonstrate a prototype "Tube" interface for the Electron alongside the Plus 3 interface at the Compec exhibition in November 1984,<ref name="elbug198501">{{ cite news | url=https://archive.org/details/elbug-magazine-1985-01/page/n23/mode/1up | title=Acorn Bits | work=ELBUG | date=January 1985 | access-date=28 December 2020 | page=24 }}</ref> although this was never brought to market directly by Acorn.

====Advanced Plus 5====
Despite Acorn's withdrawal from the Electron peripheral market, Baildon Electronics developed the Advanced Plus 5 (AP5) expansion,<ref name="ap5">{{ cite web | url=http://www.acornelectron.co.uk/info/electron/acp_pres/Advanced-Plus-5.html | title=Advanced Plus 5 | website=Acorn Electron World | access-date=28 December 2020 }}</ref> featuring Tube, 1&nbsp;MHz bus and user port interfaces, which plugged into a Plus 1 cartridge socket. This provided a sufficient level of compatibility that both the 6502 and [[Zilog Z80|Z80]] second processor products from Acorn were shown to work, providing a Tube implementation that was "as faithful as you can get", with it also being noted that the Electron being available for as little as £50 at that point in its commercial lifespan was a "very cheap way of getting a [[CP/M]] machine".<ref name="abcomputing198708">{{ cite news | url=https://archive.org/details/AB_Computing_1987-08_OCR/page/n67/mode/2up | title=Electron Plus 5 | work=A&B Computing | date=August 1987 | access-date=28 December 2020 | last1=Grace | first1=Clive | pages=68–70 }}</ref> Some differences in the memory map of the Electron meant that BBC Micro software would need modifications to work on the Electron with AP5. The price of the unit in late 1986 was £66.70.<ref name="electronuser198612">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-03/page/n66/mode/1up | title=Any port in a storm | magazine=Electron User | volume=4 | issue=3 | last1=Cook | first1=Mike | date=December 1986 | access-date=19 January 2021 | pages=67–68 }}</ref>

The additional facilities of the AP5 alongside the Tube interface permitted various expansions for the BBC Micro to be made available for the Electron. These included the Hybrid Music 5000<ref name="electronuser198810" /> and the AMX Mouse.<ref name="electronuser198612amx">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-03/page/n4/mode/1up | title=Now Electron can have its own mouse | magazine=Electron User | volume=4 | issue=3 | date=December 1986 | access-date=21 January 2021 | page=5 }}</ref>

====PMS Electron Second Processor====
In 1986, Permanent Memory Systems (PMS) announced a second processor product for the Electron, the PMS-E2P, as a self-contained cartridge for use with the Plus 1 containing a second 2&nbsp;MHz 6502A processor plus 64&nbsp;KB of RAM, priced at £89.<ref name="electronuser198607a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-10/page/n5/mode/1up | title=More speed, memory | magazine=Electron User | volume=3 | issue=10 | date=July 1986 | access-date=17 January 2021 | page=6 }}</ref> This was based on a product originally developed by John Wike of Jafa Systems.<ref name="electronuser198907" /> Available as a kit or in assembled form, it could even be adapted to connect directly to the Electron's expansion connector, thus avoiding the need to even have a Plus 1 expansion, although this would require the user to find other solutions for attaching peripherals. The implementation of the interface between the Electron and second processor was said to adhere closely to Acorn's recommendations, noting that any hardware or software compatibility issues were likely to be the fault of other vendors not similarly adhering to Acorn's guidelines.<ref>{{cite news | url=http://www.acornelectron.co.uk/mags/aab/revs/pms/r-e2p.html | title=Electron GTS | work=A&B Computing | date=April 1986 | volume=3 | issue=3 | last1=Grace | first1=Clive | archive-url=https://web.archive.org/web/20180708133459/http://www.acornelectron.co.uk/mags/aab/revs/pms/r-e2p.html |archive-date=8 July 2018}}</ref> PMS supplied Acorn's Hi-BASIC with the E2P, permitting the use of as much as 44&nbsp;KB of the second processor's RAM with BASIC programs.<ref name="electronuser198610_e2p">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-01/page/n54/mode/1up | title=High speed – and memory to match | magazine=Electron User | last1=Waddilove | first1=Roland | date=October 1986 | access-date=9 June 2023 | pages=55–56 }}</ref> The company also made a version of Computer Concepts' Wordwise Plus available for the E2P, priced at £39.95.<ref name="electronuser198703_wordwiseplus">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume4/Electron-User-04-06/page/n9/mode/2up | title=Wordwise Plus | magazine=Electron User | last1=Turnbull | first1=Steve | date=March 1987 | access-date=9 June 2023 | pages=10–12 }}</ref>

===Sound system expansions===
Despite the Electron having only limited sound generation capabilities, few expansions were offered to overcome the machine's limitations.

====Millsgrade Voxbox====
Advertised in late 1985, the Voxbox by Millsgrade Limited was an expansion connecting to the Electron's expansion connector that provided [[allophone]]-based [[speech synthesis]], with driver software provided on cassette.<ref name="electronuser198510">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-01/page/n1/mode/1up | title=Speakout with the speech synthesiser for your Electron | magazine=Electron User | volume=3 | issue=1 | date=October 1985 | access-date=29 January 2021 | page=2 }}</ref> The supplied software supported the definition of spoken words built up from the allophones{{snd}} these allophones or sounds being stored in the expansion's own ROM{{snd}} and for catalogues of words to be created and saved. A program was supplied that extended BASIC to allow the use of the synthesiser in user programs.<ref name="aeworld_voxbox">{{ cite magazine | url=http://www.acornelectron.co.uk/eug/revs/millsgrade/Voxbox_000.html | title=Voxbox (Millsgrade) | magazine=Electron User Group | issue=66 | date=March 2006 | access-date=29 January 2021 | last1=Edwards | first1=Dave }}</ref> The expansion used the [[General Instrument SP0256|General Instrument SP0256A-AL2]] speech synthesis chip.<ref name="stardot_voxbox">{{ cite web | url=https://stardot.org.uk/forums/viewtopic.php?p=271982 | title=Voxbox Question | website=stardot.org.uk | date=4 June 2020 | access-date=21 February 2021 }}</ref>

====Sound Expansion cartridge====
Originally announced in 1987 by Project Expansions to be priced at around £40,<ref name="electronuser198710se">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-01/page/n4/mode/1up | title=Electron gets Micro sound | magazine=Electron User | volume=5 | issue=1 | date=October 1987 | access-date=21 January 2021 | page=5 }}</ref> the Sound Expansion cartridge could be fitted in a Plus 1 (or compatible) slot and provide sound output equivalent to that of the BBC Micro, with Superior Software's Speech bundled as a "limited offer".<ref name="electronuser198801">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-04/page/n53/mode/1up | title='2' New Products for the Electron | magazine=Electron User | volume=5 | issue=4 | date=January 1988 | access-date=22 January 2021 | page=54 }}</ref> A product of the same name and with similar functionality was subsequently sold by Complex Software for around £55, employing its own adjustable speaker in the cartridge unit.<ref name="electronuser199005">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume7/Electron-User-07-08/page/n33/mode/2up | title=Eloquent Electron | magazine=Electron User | volume=7 | issue=8 | date=May 1990 | access-date=21 January 2021 | last1=Davidson | first1=Pete | pages=34–35 }}</ref> Superior Software had announced a version of Speech for the unexpanded Acorn Electron in 1986,<ref name="acornuser198604_electron_discounts">{{ cite magazine | url=https://archive.org/details/AcornUser045-Apr86/page/n10/mode/1up | title=Electron discounts revitalise market | magazine=Acorn User | date=April 1986 | access-date=23 February 2023 | pages=9 }}</ref> but this was never released.

====Hybrid Music 5000====
Hybrid Technology's Music 5000 was adapted and released by PRES for use with the 1&nbsp;MHz bus of the Advanced Plus 5 expansion, with the Music 5000 itself priced at £113.85. The only functional differences between the Electron adaptation and the original BBC Micro unit involved the use of Mode 6 for the display and the reduced performance of the Electron imposing some limitations on processing in programs written for the system,<ref name="electronuser198810">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume6/Electron-User-06-01/page/n7/mode/2up | title=They're playing your tune, Electron | magazine=Electron User | volume=6 | issue=1 | date=October 1988 | access-date=20 January 2021 | last1=Waugh | first1=Ian | pages=8–10 }}</ref> although this was not thought to prevent most programs for the system from working on the Electron version.<ref name="acornuser198806_hybrid">{{ cite magazine | url=https://archive.org/details/AcornUser071-Jun88/page/n56/mode/1up | title=Know the Score | magazine=Acorn User | date=June 1988 | access-date=14 March 2022 | last1=Waugh | first1=Ian | pages=55, 57, 59, 61 }}</ref>

==Legacy==
Although the Electron presented challenges to developers in terms of the amount of memory available to programs and, particularly for those writing or [[porting]] games to the machine, a reduction in hardware features useful for controlling or presenting content on the screen, developers often discovered creative workarounds to deliver commercially successful products,<ref name="electronuser198801_blake">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-04/page/n31/mode/2up | title=I must have been mad! | magazine=Electron User | date=January 1988 | access-date=28 February 2021 | volume=5 | issue=4 | last1=Blake | first1=Kevin | pages=32–33 }}</ref><ref name="electronuser198608_jacobsen">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-11/page/n39/mode/2up | title=Formula 1 | magazine=Electron User | first1=Michael | last1=Jacobsen | date=August 1986 | volume=3 | issue=11 | access-date=24 April 2021 | pages=40–41, 43 }}</ref><ref name="electronuser198805_oakden">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-08/page/n45/mode/2up | title=Quest | magazine=Electron User | last1=Oakden | first1=Tony | date=May 1988 | volume=5 | issue=8 | access-date=24 April 2021 | pages=46–48 }}</ref> making the business of writing conversions a viable one for some developers.<ref name="electronuser199006_scott">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume7/Electron-User-07-09/page/n6/mode/1up | title=Conversions are his business | magazine=Electron User | date=June 1990 | access-date=28 February 2021 | volume=7 | issue=9 | page=7 }}</ref>

Several features that would later be associated with the [[BBC Master]] and [[Acorn Archimedes|Archimedes]] first appeared as features of Electron expansion units, including ROM cartridge slots and the [[Advanced Disc Filing System]], a hierarchical improvement to the BBC's original [[Disc Filing System]].<ref name="acornuser198503b">{{ cite magazine | url=https://archive.org/details/AcornUser032-Mar85/page/n10/mode/1up | title=BBC micro upgrade likely | magazine=Acorn User | date=March 1985 | access-date=17 January 2021 | page=9 }}</ref> Having been envisaged as the basis of a portable computer with "a very strong emphasis on communications" during its development, supporting both modem and Econet interfaces,<ref name="practicalcomputing198210"/>{{rp|pages=69}} the BT Merlin M2105 product subsequently combined the Electron with communications functionality,<ref name="acornuser198406" /> and the [[Acorn Communicator]] developed such concepts further, introducing networking support.

The availability of the Electron at discounted prices from 1985 onwards led to increased demand for third-party software and expansions for the machine.<ref name="electronuser198605">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume3/Electron-User-03-08/page/n4/mode/1up | title=Electron boom creates more jobs | magazine=Electron User | volume=3 | issue=8 | date=May 1986 | access-date=17 January 2021 | page=5 }}</ref> While it may not have been as popular as the Spectrum, Commodore 64 or [[Amstrad CPC]], it did sell in sufficient numbers to ensure that new software titles from established producers were being produced right up until the early 1990s,<ref name="electronuser199007a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume7/Electron-User-07-10/page/n5/mode/1up | title=E-Type draws the crowds | magazine=Electron User | volume=7 | issue=10 | date=July 1990 | access-date=29 January 2021 | page=6 }}</ref> with mainstream publications dedicated to the machine having effectively supported it for five years beyond the point at which Acorn's own support had ceased.<ref name="electronuser199007b">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume7/Electron-User-07-10/page/n5/mode/1up | title=It's goodbye - and hello! | magazine=Electron User | volume=7 | issue=10 | date=July 1990 | access-date=29 January 2021 | page=6 }}</ref> One reviewer concluded that even at this point in 1990, "Electron owners wishing to upgrade their machine will find themselves better served now than at any time in the machine’s history."<ref name="acornuser199004_emblem">{{ cite magazine | url=https://archive.org/details/AcornUser093-Apr90/page/n115/mode/2up | title=Sum of the Parts | magazine=Acorn User | last1=Emblem | first1=Bernard | date=April 1990 | access-date=19 January 2024 | pages=114–115, 117 }}</ref>

==See also==
* ''[[Electron User]]'', the most popular Acorn Electron focused magazine

==Notes==
{{reflist|group=note}}

== References ==
{{reflist}}

==External links==
{{Commons category}}
* [http://www.stairwaytohell.com Stairway To Hell]
* [https://www.8bitkick.cc/playuef.html Acorn Electron tape archive{{snd}}playUEF@8bitkick]
* [http://www.acornelectron.co.uk Acorn Electron World]
* [https://web.archive.org/web/20190809232748/http://www.bygonebytes.co.uk/Mode7.html Electron MODE 7 Photos]

{{Acorn computers}}

[[Category:Acorn Computers|Electron]]
[[Category:6502-based home computers]]
[[Category:Home computers]]
[[Category:Computer-related introductions in 1983]]
[[Category:Computers designed in the United Kingdom]]