The Z80 at 45: Why a 1976 CPU Refuses to Die

Zilog’s Z80, released in 1976, became one of the most enduring microprocessors ever made. Designed by a team under Federico Faggin — who had already led Intel’s 4004 and 8080 — it was binary-compatible with the 8080 but added registers, a richer instruction set, a single 5V supply, and built-in DRAM refresh logic, making it cheaper and easier to design around. That combination made it the engine of a generation of computing: the TRS-80, Sinclair ZX Spectrum, MSX machines, countless CP/M business systems, and, in modified form, handhelds and game consoles.

The article’s core point, signaled by its title, is that the Z80 never really became a museum piece. Long after it stopped powering desktop PCs, it lived on in embedded controllers, industrial equipment, calculators (notably TI’s graphing-calculator line), and as a secondary or sound processor in game hardware. Decades of second-sourcing, clones, and derivative cores kept the architecture in continuous production and in engineering curricula as a teaching example of clean 8-bit design.

The broader significance is a case study in technological longevity: a well-designed, well-documented, widely-cloned architecture can outlast its original market by decades because the ecosystem, tooling, and installed base carry it forward. (Note: Zilog has since announced end-of-life for the original Z80 part, in 2024 — after this 2021 article was written.)