[xen2xen1]

Gates had a version of DOS ready in 6 weeks, while DR was still planning DOS. MS got things going much faster.

[rbanffy]

No. He ran out and acquired 86-DOS, from Seattle Computer Products. It's easy to have something when you buy it already complete.

And DR had CP/M-86.

[whobre]

DRI did not have CP/M-86 at that time which is the reason Tim Paterson developed 86-DOS in the first place.

[rbanffy]

CP/M-86 was first expected to be delivered in 1979, so I assume it existed in one form or another prior to that, shipments pending hardware availability. I wouldn't expect DRI to fund the adaptation without a cooperative manufacturer unless there were a significant installed base.

[canucker2016]

MS still had to make modifications to Tim Patterson's 86-DOS before it shipped as PC-DOS 1.0 - source: Paul Allen's Idea Man autobiography.

[rbanffy]

Of course - the PC didn't exist when SCP made 86-DOS. The same way as with CP/M, the hardware interface had to be written.

[indigodaddy]

Same thing, he did the needful to have something to give ibm.

[lproven]

> DR was still planning DOS

No, DR was planning CP/M-86.

I feel like I'm going down this thread posting corrections, but when trying to thrash out the details, I think it's vital to get the details right.

DR was about 3Y late with CP/M-86. The 8086 shipped in 1979, IIRC -- I was only 12 -- and there was no CP/M yet. The IBM PC shipped in 1981. Still no CP/M.

Tim Paterson, author of QDOS, went on record as saying he'd never have bothered if CP/M-86 had actually shipped.