Private company
Mark Williams Company
Logo: Mark Williams Company, Copyrighted free use, via Wikimedia Commons3
Software company that created Coherent
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. It was founded by Robert Swartz (father of Aaron Swartz) in 1977 and discontinued operations in 1995. The name comes from the middle name of Robert Swartz's father, William Mark Swartz.2 Wikipedia text CC BY-SA 4.0
Last updated Oct 21, 2026.
Overview
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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. It was founded by Robert Swartz (father of Aaron Swartz) in 1977 and discontinued operations in 1995. The name comes from the middle name of Robert Swartz's father, William Mark Swartz.2
Products and brands
- Coherent
Listed on Wikidata.1
Produced Coherent, a clone of Unix.
csd, C source debugger.
Let's C, low-cost professional C compiler for the IBM PC and MS-DOS.
Mark Williams C for CP/M-86.
Read the full text
Mark Williams C for the Atari ST, first major C programming environment for the ST computers.
XYBasic, a process control BASIC running on CP/M that could be burned on to memory (EPROM) and run on an 8080 standalone processor.
From Wikipedia’s article on Mark Williams Company, shared under CC BY-SA 4.0.4
Timeline
- 1980Founded Founded1
Links
- WikipediaMark Williams Company
- WikidataQ1900511
Sources
The numbers on this page point here. Each one links to the record it came from.
- 1
- 2WikipediaMark Williams Company on Wikipedia
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