Answer 8—In the late 1970s, Motorola introduced the MC14500 industrial control unit, a one-bit microcontroller “designed for use in systems requiring decisions based on successive single-bit information.” It has a 1-bit wide data bus and a 4-bit instruction bus. It comes in a 16-pin package, DIP, or SOIC. It can be clocked at anywhere from DC to 1 MHz. Both the program counter and program memory are external to the chip, but give it dubious claim to being a true microprocessor. It was still being produced as late as 1997.

Contributor: David Tweed