One could claim that the IBM PC was not really IBM’s first PC at all.
In September 1975 the company introduced the IBM 5100, its first “portable” computer. (“Portable” meant that it weighed just 55 pounds and you could buy a special travel case to lug it around in.)
The 5100 was not technically a microcomputer; it used a processor IBM had developed in-house called the PALM which was spread over an entire circuit board rather than being housed in a single microchip.
From the end user’s standpoint, however, that made little difference; certainly it would seem to qualify as a personal computer if not a microcomputer.
It was a self-contained, Turing complete, programmable machine no larger than a suitcase, with a tape drive for loading and saving programs, a keyboard, and a 5-inch screen all built right in along with 16K or more of RAM.
Read 55 remaining paragraphs