Re: R&D and the Aquaduct
> MS May have purchased the QDOS poduct, but it was barely functional and certainly needed a very large amount of bug fixes and development before it was released.
When MS bought DOS from SCP it was _already_ being distributed as SCP-DOS (or 86-DOS) and was sold with SCP's Zebra 8086 S100 boxes.
Certainly it was modified to use MS's FAT file system rather than the CP/M cloned file system.
> It was then IIRC totally re-written from the ground up for the next major release.
It was rewritten by IBM when Gary Kildall demonstrated PC-DOS 1.0 showing a DRI copyright notice that was buried deeply in the code. Both MS and SCP were CP/M OEMs. SCP with their Zebra 8 bit systems and MS with the Z80 Softcard. It has been alleged that SCP decompiled the CP/M BDOS (there were commented decompilers available at that time - see Byte magazine ads) and put the code through Intel's 8-16 bit ASM converter (also available) to arrive at the initial QDOS.
After IBM rewrote PC-DOS as 1.1 it was passed back to MS to create MS-DOS 1.25.
It was rewritten again to make 2.x and to include hard disk support (which had been available for several years on CP/M).