Actually, Microsoft was a late comer to personal computers. I own
(still) an Altair 8800B, and owned a
Morrow Microdecision before that, both on CP/M. And prior to that I had
systems that ran various other OS's
that were a bit more limited, and one straight bootstrap system for
which you had to furnish an OS of your favorite
flavor. Microsoft did not create, or really enable personal computers,
they just got the contract to write the OS for IBM, and were able to
bootstrap that into the corporation you see today.
Microsoft's entry into the personal computer market was by supplying
a version of BASIC that for several operating systems. I can
remember loading it from tape, and later burning it to EPROM with a
small relocation program to move it into RAM at the address it
expected to run. (It was not relocatable...)
Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!