PSOS (real-time operating system)
| Developer | Alfred Chao / SCG / ISI / Wind River Systems |
|---|---|
| Written in | 68000 assembler |
| OS family | Real-time operating systems |
| Working state | Discontinued |
| Source model | Closed source |
| Initial release | 1982 |
| Marketing target | Embedded systems |
| Platforms | Motorola 68000 |
| Kernel type | Real-time |
| License | Proprietary |
pSOS (Portable Software On Silicon) is a real time operating system (RTOS), created in about 1982 by Alfred Chao, and developed/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 systems based on the Motorola 68000 family architecture, because it was written in 68000 assembler and was highly optimised from the start. It was also modularised, with early support for OS-aware debugging, plug-in device drivers, TCP/IP stacks, language libraries and disk subsystems. Later came source-level debugging, multi-processor support and further networking extensions.
In about 1991, Software Components Group was acquired by Integrated Systems Inc. (ISI) who further developed pSOS - now restyled pSOS+ - for other microprocessor families, by rewriting the greater part of it in C. Attention was also paid to supporting successively more integrated development environments, culminating in pRISM+.
In July 1994, Integrated Systems acquired Digital Research's modular real-time multi-tasking operating system FlexOS from Novell.
In 1999 Integrated Systems Inc. was acquired by Wind River Systems, the originators of 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 itself will be made.
NXP Semiconductors acquired pSOS for TriMedia from Wind River and continued to support this OS for the TriMedia VLIW core.
In March 2000, rival company Express Logic released their Evaluation Kit for pSOS+ users, designed to provide a migration path to its ThreadX RTOS.
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