Zilog Z80 Turns 50 as Open-Source Replacement Nears Drop-In DIP40 Silicon

The Zilog Z80, an iconic 8-bit CPU launched in July 1976, has turned 50 years old. It remained in production for 48 years until Zilog (a Littelfuse subsidiary) stopped accepting orders in June 2024. The original chip packed 8,500 transistors on a 4μm process and ran at 2.5 MHz, powering devices like the ZX Spectrum, Game Boy, and Pac-Man arcade cabinet. Following the end-of-life notice, Renaldas Zioma's open-source FOSS Z80 project has produced working silicon, with a drop-in replacement for the original 40-pin DIP package now in development. The design uses Guy Hutchison's TV80 Verilog core and targets clock speeds up to 50 MHz on 130nm CMOS, compared to the original's 4 MHz. Zilog is also phasing out the eZ80L92 successor due to low demand, though the eZ80 architecture remains in TI calculators. Hobbyists continue to find new uses for the Z80, including running a tiny conversational AI on 64KB of RAM.