History of UNIX operating system. In 1969 Bell Labs was heavily involved with an operating system named Multics, a large multi-user op/sys running on a General Electric maneframe. In 1969 support for Multics was withdrawn leaving two men, Ken Thompson and Dennis Ritchie, wanting a comparable yet simpler alternative. Multics had grown immensely and become unmanageable by a small team of programmers. So Ritchie and Thompson did what many people wish they had the time and ability to do - they designed their own operating system from scretch. Thompson located an abandoned Digital PDP-7 in the basement of Bell Labs and commenced work producing an operating system on which a team of programmers could easily coordinate their efforts. It is often rumoured that Thompson actually wanted an independent op/sys on which he could develop software for a multi-player star-wars type program in 3D! However to appease management Thompson recognized that he must have a real application and so he asked the Bell Labs Legal Department if they would test his ducument preparation system - which they loved. A early version of the UNIX System was delivered to them on a PDP-11/20 in 1971. Thompson's initial efforts culminated in the blah development of an operating system, PDP-7 assembler and several utility programs. In 1973 Dennis Ritchie was working on a programming language for operating system development, basing his ideas upon BCPL, he developed B and finally created one called C. By the end of 1973, the UNIX kernal was written (85%) in C which enabled it to be ported to other machines for which a C compiler could be fashioned. This was a great step blah blah blah 'cos it no longer tied the operating system to the PDP-7 as it would have been if it remained in assembly language. The first big such move was made in 1976 when Dennis Ritchie and Stephen Johnston ported UNIX to an Interdata 8/32 machine. Since then UNIX has been ported by many people to many different single processor machines.