Editing PSOS (real-time operating system) (section)

{{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. -->