Linus Torvalds use of assembly language. After the VIC-20 he purchased a Sinclair QL, which he modified extensively, especially its operating system. "Because it was so hard to get software for it in Finland, Linus wrote his own assembler and editor (in addition to Pac-Man graphics libraries)" for the QL, as well as a few games. He wrote a "Pac-Man" clone named "Cool Man". On January 5, 1991 he purchased an Intel 80386-based clone of IBM PC before receiving his MINIX copy, which in turn enabled him to begin work on Linux. The first prototypes of Linux were publicly released later that
Cray Operating System Cray Operating System The Cray Operating System (COS) succeeded Chippewa Operating System (shipped with earlier computer systems CDC 6000 series and CDC 7600) and is Cray Research's now discontinued proprietary operating system for its Cray-1 (1976) and Cray X-MP supercomputers, and those platforms' main OS until replaced by UNICOS in the late 1980s. COS was delivered with Cray Assembly Language (CAL), Cray FORTRAN (CFT), and Pascal. As COS was written by ex-Control Data employees, its command language and internal organization bore strong resemblance to the SCOPE operating system on the CDC 7600 and before that EXEC*8 from CDC's earlier ERA/Univac