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

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-computers-skirted-ibms-patents-and-gave-rise-to-eisa/ https://www.allaboutcircuits.com/news/how-compaqs-clone-comp... https://www.quora.com/How-is-the-BIOS-for-a-computer-motherboard-written-How-was-the-first-BIOS-written/answer/Ira-J-Perlow https://www.quora.com/How-is-the-BIOS-for-a-computer-motherb...