It wasn’t intended that way originally, it was the developers of the time who started hitting the hardware directly. Software written to use the BIOS and DOS in

It wasn’t intended that way originally, it was the developers of the time who started hitting the hardware directly. Software written to use the BIOS and DOS interfaces could run on other non-IBM-compatible MS-DOS computers that existed. But that didn’t offer the performance that demanding tasks like gaming required, and that’s the genesis of the difference between “IBM-compatible” and “MS-DOS compatible”.