View source for PSOS (real-time operating system)

{{Short description|None}}
{{Lowercase|title=pSOS}}
{{Use dmy dates|date=April 2019|cs1-dates=y}}
{{Use list-defined references|date=December 2021}}
{{Anchor|SCG|ISI}}
{{Infobox OS
| name = pSOS
| logo =
| screenshot =
| caption =
| developer = Alfred Chao, Software Components Group (SCG)<br/>[[Integrated Systems Inc.]] (ISI)<br/>[[Wind River Systems]]
| source model = [[Closed source]] (original)<br/>[[Open source]] (later variants)
| kernel type = [[Real-time operating system|Real-time]] [[Monolithic kernel|monolithic]]
| supported platforms = [[Motorola 68000 series]]
| ui =
| family = 
| released = {{Start date and age|1982}}
| latest release version = Reliant (RoweBots)
| latest release date = {{Start date and age|2007|08}}
| marketing target = [[Embedded system]]s
| programmed in = 68000 [[assembly language]]
| language = English
| update model =
| package manager =
| working state = Discontinued
| license = [[Proprietary software|Proprietary]]
| website =
}}

'''pSOS''' ('''Portable Software On Silicon''') is a [[real-time operating system]] (RTOS), created in about 1982 by Alfred Chao, and developed and marketed for the first part of its life by his company Software Components Group (SCG). In the 1980s, pSOS rapidly became the RTOS of choice for all [[embedded system]]s based on the [[Motorola 68000 series]] family architecture, because it was written in 68000 [[assembly language]] and was highly optimised from the start. It was also modularised, with early support for OS-aware debugging, plug-in [[device driver]]s, [[Internet protocol suite]] (TCP/IP) stacks, language [[Library (computing)|libraries]], and disk subsystems. Later came [[source code]] level debugging, [[multiprocessing]] support, and further [[computer network]]ing extensions.

In about 1991, Software Components Group was acquired by [[Integrated Systems Inc.]] (ISI) which further developed pSOS, then renamed as pSOS+, for other microprocessor families, by rewriting most of it in the [[programming language]] [[C (programming language)|C]]. Attention was also paid to supporting successively more [[integrated development environment]]s, culminating in pRISM+.

In July 1994, ISI acquired [[Digital Research]]'s modular real-time multi-tasking operating system [[FlexOS]] from [[Novell]].<ref name="pNDE"/>

In 1995, ISI offered a <code>pSOSystem/NEST</code> package for [[Novell Embedded Systems Technology]] (NEST).<ref name="Novell_1995_NEST"/><ref name="pNDE"/>

In February 2000, ISI was acquired by [[Wind River Systems]], the originators of the rival RTOS [[VxWorks]]. Despite initial reports that pSOS support would continue, development was halted. Wind River announced plans for a 'convergence' version of VxWorks which will support pSOS system calls, and that no further releases of pSOS will occur.

[[NXP Semiconductors]] acquired pSOS for [[TriMedia (mediaprocessor)|TriMedia]] from Wind River and continued to support this OS for the TriMedia [[very long instruction word]] (VLIW) core.<!-- Likely not after 2010, when NXP's TriMedia group was terminated. -->

==Migration away from pSOS==
In March 2000, rival company [[Express Logic]] released their Evaluation Kit for pSOS+ users, designed to provide a migration path to its [[ThreadX]] RTOS.

During August 2000, MapuSoft Technologies Inc. came up with the pSOS OS Changer porting kit which can smoothly move the software to multiple OS such as [[Linux]], VxWorks, and more. It includes an ''[[integrated development environment]]'' (IDE) and ''application programming interface'' ([[API]]) optimization along with a profiling tool to measure API timing on target boards (www.mapusoft.com). 

In August 2007, RoweBots, a former partner of SCG and ISI, [[open source]]d their pSOS+ compatible version called Reliant. It is available to all that wish to upgrade without application changes.

The [[Xenomai]] project supports pSOS+ APIs (and others traditional RTOS APIs) over a Linux-based real-time framework to allow existing industrial applications to migrate easily to a Linux-based environment while keeping stringent real-time guarantees.

Another open sourced alternative is [[RTEMS]], which has support for various APIs, including the "Classic API" (compatible to pSOS) and the POSIX API. Compared to Linux, RTEMS is a closer match to pSOS applications due to its lower memory size and its strict realtime behaviour.

Popular ''Secure Sockets Layer'' (SSL), now ''[[Transport Layer Security]]'' (TLS), libraries such as [[wolfSSL]] still support pSOS.

==See also==
* [[FlexOS]]
* [[Novell Embedded Systems Technology]] (NEST)
* [[UNIX System V STREAMS]]

==References==
{{Reflist|refs=
<ref name="pNDE">{{cite web |title=pSOSystem and the NEST Development Environment - Designing Embedded Applications with NetWare Connectivity |type=White paper |publisher=[[Integrated Systems, Inc.]] (ISI) |date=1998 |url=http://www.isi.com/Products/pSOS/Networking/pNDE.html |url-status=dead |archive-url=https://web.archive.org/web/19980219173150/http://www.isi.com/Products/pSOS/Networking/pNDE.html |archive-date=1998-02-19}}</ref>
<ref name="Novell_1995_NEST">{{cite web |title=Novell Announces RTOS Vendor Program Which Brings Integrated Networking Solutions to the Embedded Systems Marketplace |type=Press Release |date=1995-05-23 |location=Orem, UT, USA |publisher=[[Novell, Inc.]] |url=http://www.novell.com/news/press/archive/1995/05/pr00121.html |access-date=2018-08-18 |url-status=live |archive-url=https://web.archive.org/web/20180818184611/https://www.novell.com/news/press/archive/1995/05/pr00121.html |archive-date=2018-08-18 |quote="Because [[Novell]] used [[Integrated Systems Inc.|Integrated Systems]]' [[FlexOS]] during the development and testing of NEST, we are in the unique position of supporting it through both our real-time product lines pSOSystem for deeply embedded markets, and FlexOS for [[point of sale]]," said Moses Joseph, vice president of marketing for Integrated Systems. "Developers using the FlexOS development kit and the expanded pSOSystem/NEST package for everything from home security and entertainment to office automation and global communications applications, now have quick and easy access to the widest variety of standard networking protocols.}}</ref>
}}

==Further reading==
* {{cite web|title=pSOSystem|last=|first=|website=|publisher=[[Integrated Systems, Inc.]] (ISI)|date=1998|url=http://www.isi.com/Products/pSOS/|url-status=dead|archive-url=https://web.archive.org/web/19980219171501/http://www.isi.com/Products/pSOS/|archive-date=1998-02-19|access-date=}}
* {{cite web |title=Express Logic announcement of their Evacuation Kit |url=http://www.rtos.com/news/detail/?prid=11 |url-status=dead |access-date=2007-06-13 |archive-url=https://web.archive.org/web/20070928131427/http://www.rtos.com/news/detail/?prid=11 |archive-date=2007-09-28}}

{{Real-time operating systems}}

{{DEFAULTSORT:Psos}}
[[Category:Real-time operating systems]]
[[Category:1982 software]]