Personal computer history doesn’t begin with IBM or Microsoft, although Microsoft was an early participant in the fledgling PC industry.
The first personal computers, introduced in 1975, came as kits: The MITS Altair 8800, followed by the IMSAI 8080, an Altair clone. (Yes, cloning has been around that long!) Both used the Intel 8080 CPU. That was also the year Zilog created the Z-80 processor and MOS Technology produced the 6502. Bill Gates and Paul Allen wrote a BASIC compiler for the Altair and formed Micro-soft.
In 1976, Apple’s two Steves (Jobs and Wozniak) designed the Apple I, Apple’s only “kit” computer (you had to add a keyboard, power supply, and enclosure to the assembled motherboard), around the 6502 processor. That was also the year that Electric Pencil, the first word processing program, and Adventure, the first text adventure for microcomputers, were released. Shugart introduced the 5.25″ floppy