UNIX was developed in 1971 (research project started in 1969) by Ken Thompson and Dennis Ritchie (also the author of the programming language C) at AT&T's Bell Laboratories for use on its DEC minicomputers. First written in assembly language, then rewritten in C. When developing UNIX, they had a generic operating system in mind. They intended to develop an operating system that works with more than one manufacturer's computer system.
How? The answer was using different C compilers to compile the kernel source code for different CPUs on different computers and using different device drivers for different hardware from different vendors.
UNIX is a multiuser multitasking operating system. Multiuser was implemented with time sharing, and multitasking was with event-driven.
UNIX is very powerful but not very user friendly. For UNIX to become so successful and popular it will involve a social factor, the "UNIX graduate" phenomenon. In the late 1970s, Bell gave away UNIX to many Colleges and Universities, and students became accustomed to using it. Consequently, when many of these graduates entered the work force, they began agitating for the acceptance of UNIX in the industry. The key supporters - the scientific community, the federal government, and the aerospace industry - often named UNIX in their bid specification to computer manufacturers. In fact, they said "
If you want our business, you better offer a system that includes UNIX." Today UNIX runs on almost every type of computers, from the supercomputers to personal computers.
Another important factor for UNIX popularity was the Internet. TCP/IP (Transmission Control Protocol/Internet Protocol) was first implemented on BSD (Berkeley implementation of UNIX). At the early stage, the operating systems on the Internet were only UNIX. Only after TCP/IP was imported to other operating systems were they able to connect to the Internet.
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