Gates 'cause he had done a good job with a compiler.
Interpreter.
MS BASIC. Ironically ported from the "free" Dartmouth BASIC, a cut down version of ForTran, for teaching at Dartmouth. Most of the porting done by Bill Gate's friend (I forget which one! Wiki says Paul Allen and Monte Davidoff) initially to 8080 cpu than later 6502. Most 8 bit home computers before PC shipped with it. The Apple II didn't use the MS 6502 BASIC, but Applesoft Basic was certainly later and similar.
When requested to do an OS, he told 'em what they wanted already existed, more or less, no need to start from scratch, and sent them to the CP/M fellow, trying to do him a good turn. But the CP/M guy (who was pretty strange, and later was killed in a biker bar brawl) stood up the IBM guys, who were NOT impressed with his - ahem - business like behaviour.
I think it was more complicated than that. Bizarrely IBM already had suitable HW and OS, but the PC wasn't meant to compete with existing IBM products, it was an unimportant thing originally, hence stock hardware and software design thrown together very quickly.
I don't think anyone exactly knows what happened between
Digital Research's Gary Kiddal and IBM.
DRI did eventually sue MS, but there was some sort of secret settlement.
There was more trouble later, first with marketing then with Windows:
The competition between MS-DOS and DR-DOS is one of the more controversial chapters of microcomputer history. Microsoft offered the best licensing terms to any computer manufacturer that committed to selling MS-DOS with every system they shipped, making it uneconomical for them to offer systems with another OS, since the manufacturer would still be required to pay a license fee to Microsoft for that system. This practice led to a US Department of Justice investigation, resulting in a decision in 1994 that barred Microsoft from "per-processor" licensing.
[8]
MS purchased 86-DOS and repackaged it as MS-DOS and PC-DOS.
MS Word and Excel for Mac were MS's first two genuine own products!
The DRI story really ends in 1991 when Novell bought them.
There was once a company called
Santa Cruz Operation and they sold Xenix, which curiously once belonged to MS.
Caldera bought the Digital Research stuff from Novell and also the remains of the original SCO. They then renamed themselves
SCO Group and became trolls. They tried to sue IBM and others for using UNIX and Linux without a licence from them. A sort of
Dickensian law suit that went on for ever (2002 to 2016)!
From Wikipedia:
List of recent SCO Group* lawsuits
[* no connection with original SCO]
ran XP for a little while on an HP that came with it. Which was a fsckin nightmare for which I purely blame HP, not MS.
I'd blame MS, they ALWAYS shipped every Windows with
STUPID defaults. All eye candy on, desktop indexing, all server type services running, etc, default user account as Admin. We used to spend a few hours fixing the settings, which might double speed of operation and reduce boot time from 1 minute to 14 seconds on a 2012 computer.
On big rollouts we used SMS on a server to automatically fix it all on maybe 30 to 500 PCs at once.
All the junk OEMs add doesn't help.
