[m463]

IBM designed the original ISA bus PC. But with microsoft's non-exclusive agreement it was able to sell MS-DOS, and it kickstarted early clones like compaq. IBM tried to close things down with the PS/2 OS/2 and microchannel, but they couldn't close the barn door.

here's another fun article: https://www.joelonsoftware.com/2002/06/12/strategy-letter-v/

[canucker2016]

Besides a license for MSDOS, the PC clone makers also needed a compatible BIOS. Compaq was the first out of the gate with a mostly-compatible IBM PC BIOS.

The IBM PC-compatible BIOS from Phoenix Technologies allowed more companies to jump in the PC clone wars.

https://www.allaboutcircuits.com/news/how-compaqs-clone-comp...

https://www.quora.com/How-is-the-BIOS-for-a-computer-motherb...