Cray operating system

Cray Operating System (COS) is a proprietary operating system developed by Cray Research for its Cray-1 (1976), Cray X-MP (1982) supercomputers . It was the main one for these platforms until the release of UNICOS in 1985 simultaneously with the release of Cray-2 , where the main OS became UNICOS , and COS became optional. COS came with development tools in Cray Assembler Language (CAL), Cray FORTRAN (CFT) and Pascal .

Since COS was written by former employees of Control Data Corporation (CDC), its command language and internal organization is very similar to the SCOPE operating system for the CDC 7600 computer and the even earlier EXEC * 8 ​​OS used in earlier CDC designs for the ERA series / UNIVAC . User tasks for COS were transmitted through a communication computer , which was connected to the supercomputer with a high-speed communication channel and was called station software . The communication computer was usually IBM or CDC mainframes , as well as DEC VAX mini-computers . Interactive work with COS was also possible through a communication computer, but most users preferred to simply give out batch jobs.

The data permanently stored on the disk used in the user program was “local” for a separate task. When the task was completed, its local data had to be returned and restored. To hold data between tasks, they had to be explicitly designated as “permanent” (permanent). Tape work was also supported if the Cray computer was equipped with an I / O subsystem.

COS also provided job scheduling and a means of restarting from a checkpoint to manage large workloads, even when the system was idle (planned or unscheduled).

Internally, COS was divided into very small messaging controllers and many system task processors. Each STP was essentially similar to peripheral data processing software in the early Control Data operating systems. For example, PDM was used to manage persistent data, TDM for tape data, DQM to manage disk requests, etc.

The source code of COS version 1.13 was declared public domain , its copies were not preserved, and therefore COS was considered lost until in 2012 one of the users was discovered and uploaded to the Internet disk image with version 1.17. ^[one]