<i>&quot;The only reason why IBM chose DOS instead of CP&#x2F;M is that DOS cost less per license than CP&#x2F;M.&quot;</i><p>IBM didn&#x27;t choose DOS; the market did. The original PC could be bought with either PC-DOS, CP&#x2F;M-86, or UCSD p-System.<p>IIRC, the DOS version was cheaper, and, possibly, available a few months earlier, but in those times, the latter did not imply that the race was run before it started in those times.