Coherent (operating system)The Coherent operating system was
introduced in 1983 by the now-defunct Mark Williams Company as
one of the first Unix-like computer operating 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. 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.