5 ms·
What I find interesting is that PC-DOS (MS-DOS) was also a mostly clean room copy of CP/M. The guy who wrote it before Microsoft acquired it literally went thr
by rpiguy 8y ago
What I find interesting is that PC-DOS (MS-DOS) was also a mostly clean room copy of CP/M.
The guy who wrote it before Microsoft acquired it literally went through a CP/M programming manual and recreated the system calls for x86, changing a name here or there.
Neat parallel to how NT doesn't copy any VMS code, but still essentially copies VMS in several aspects.
- bonzini 8y agoAnd the new MS-DOS 2.0 APIs were based on Unix, sometimes down to the name (for example INT 21h/AH=42h is named LSEEK, and the value you put in AL matches exactly the "whence" argument of the Unix syscall lseek)
- nineteen999 8y agoThere was a nice analysis of this done by Bob Zeidman where he compared the released CP/M 2.0 and DOS 2.0 source code. His basic conclusion was that source and basic commands were not copied, but that a large number of the system calls were copied. https://www.scirp.org/journal/PaperInformation.aspx?PaperID=71259 https://www.scirp.org/journal/PaperInformation.aspx?PaperID=...
- JetSpiegel 8y agoDramatized in the first season of Halt and Catch Fire. That show is a mishmash of all lore from that era.