Coherent was able to run on most Intel-based PCs with Intel 8088, 286, 386, and 486 processors and, like a true Unix, was able to multitask and support multiple users. Coherent also had support for X11 and MGR windowing systems.
Later versions of Coherent (version 4 and higher) supported features common in modern Unix-like systems, including virtual memory with demand paging, a version of MicroEMACS, access to DOS FAT16 File systems, an optimizing C compiler with linker, and a modified version of Taylor UUCP. The final releases of Coherent also fully supported the iBCS COFF binary standard, which allowed binary compatibily with SCO Unix applications, including WordPerfect, Lotus 1-2-3, and several Microsoft applications including QuickBASIC, Microsoft Word, and MultiPlan. Coherent predates both MINIX and Linux by many years.
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.
Much of the operating system was written by ex-students from the University of Waterloo: Tom Duff, Dave Conroy, Randall Howard, Johann George, and Trevor John Thompson. Significant contributions were also made by people such as Nigel Bree (from Auckland, New Zealand). Nigel went on to write "Ghost" - later bought out and fully commercialized as Norton Ghost.
The Mark Williams Company closed in 1995.
Some websites offer Coherent for download, although the copyright status of it nowadays is unclear. While Coherent does not have the features of a modern Unix-like OS such as Linux, it is still a viable solution for those looking to run Unix on a very old computer such as a 286-based machine.
Sources are available for version 4.2.14. However, they don't work. Sources for the latest available version are also available, but under NDA.