The Coherent operating system was introduced in 1983 by the now-defunct Mark Williams Company as one of the first Unix-like systems for IBM PC-compatible computers. Coherent was capable of running on most Intel-based PCs with 286, 386, and 486 processors and, like a true Unix, was capable of multitasking and of having multiple users. Coherent also had support for X11. In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. ... 1983 is a common year starting on Saturday of the Gregorian calendar. ... The Mark Williams Company was a small company outside Chicago, Illinois that wrote Coherent, one of the first Unix-like operating systems for IBM PCs. ... A Unix-like operating system is one that behaves in a manner similar to a UNIX system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification. ... The tower of a personal computer. ... The Intel 80286 is an x86-family 16-bit microprocessor that was introduced by Intel on February 1, 1982. ... An Intel 80386 Microprocessor The Intel 80386 is a microprocessor which was used as the central processing unit (CPU) of many personal computers from 1986 until 1994 and later. ... Intel i486 DX2- top view The Intel i486 (also called 486 or 80486) is a range of Intel CISC microprocessors which is part of the Intel x86 family of processors. ... Microprocessors, including an Intel 80486DX2 and an Intel 80386 A microprocessor (abbreviated as µP or uP) is an electronic computer central processing unit (CPU) made from miniaturized transistors and other circuit elements on a single semiconductor integrated circuit (IC) (aka microchip or just chip). ... UNIX is a portable, multi-tasking and multi-user computer operating system originally developed by a group of AT&T Bell Labs employees including Ken Thompson, Dennis Ritchie, and Douglas McIlroy. ... 1. ... In computing, the X Window System (commonly X11 or X) is a windowing system for bitmap displays. ...

Coherent is sometimes mistakenly referred to as "Coherent Unix", which is incorrect. Coherent was based on the specifications of Unix Version 7, without reference to any of the Unix source code, either from Bell Labs or BSD. Early Unix releases were named based on the edition of the documentation that described them. ... Bell Telephone Laboratories or Bell Labs was originally the research and development arm of the United States Bell System, and was the premier corporate facility of its type, developing a range of revolutionary technologies from telephone switches to specialized coverings for telephone cables, to the transistor. ... Berkeley Software Distribution (BSD) is the UNIX derivative distributed by the University of California, Berkeley starting in the 1970s. ...

Much of the operating system was written by ex-students from the University of Waterloo: Tom Duff, Dave Conroy, Randall Howard, and Johann George. The University of Waterloo, also known as UW or simply Waterloo, is a medium-sized research-intensive public university in the city of Waterloo, Ontario, Canada. ... Tom Duff (Thomas Douglas Selkirk Duff, born December 8, 1952) is a computer programmer. ...

The Mark Williams Company went bankrupt in 1995. Bankruptcy is a legally declared inability or impairment of ability of an individual or organization to pay their creditors. ... 1995 was a common year starting on Sunday of the Gregorian calendar. ...

External links

• comp.os.coherent FAQ link (http://groups.google.com/groups?selm=9506041157.AA2295.V3.4%40taco.tlug.org&oe=UTF-8&output=gplain)
• Andrzej Popielewicz's GNU stuff for Coherent website (http://www.landibase.com/coherent.html)
• Victor M. Varela Coherent page (http://www.nivel0.net/Coherent)
• FTP archive for Coherent at Demon Internet (ftp://ftp.demon.co.uk/pub/coherent/)
• Coherent history archive (http://neil.franklin.ch/Usenet/alt.folklore.computers/20001107_Coherent)