The Mark Williams Company was a small software company in Chicago, Illinois (later moved to Northbrook) that created Coherent, one of the first Unix-like operating systems for IBM PCs and several C programming language compilers.

Robert Swartz moved the company (originally producing a soft drink called Dr. Enuf[2][3]) into software with his father's help and the company became known as the Mark Williams Company.

Linux had made serious inroads in the UNIX clone market.

Since Coherent was a commercially available package and Linux was distributed freely on the Internet via their GNU General Public License, Coherent sales plummeted and Swartz had no choice but to cease operations in 1995.

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