[KCUOJJQJ]

>The original version of DOS that Microsoft bought to license to IBM for the PC was written in 6 weeks.

Is this actually true? From https://en.wikipedia.org/wiki/Tim_Paterson

When a book appeared in 2004 claiming that 86-DOS was an unoriginal "rip-off" of CP/M,[6] Paterson sued the authors and publishers for defamation.[7][8] The judge found that Paterson failed to provide any evidence regarding "serious doubts" about the accuracy of the Gary Kildall chapter.

[mrunkel]

Even a "rip-off" takes time to write. I'm not sure what you're questioning.

It wasn't a direct copying of the code, but the API was largely similar to CP/M.