As early as the mid-1970s, minicomputers and mainframes started incorporated microprocessors for things like system monitoring, booting, and peripheral interfac

As early as the mid-1970s, minicomputers and mainframes started incorporated microprocessors for things like system monitoring, booting, and peripheral interfaces. In 1981, the original IBM PC's keyboard had a 8048 microcontroller internally to handle communication with the PC. Architecturally, this is still how it's done, usually just all shrunk down to a single IC now. Pretty much any expansion card or USB device will have a microcontroller in it, possibly multiple.