There were several commercial co-processors for the Tube, including ones with a 6502, a Z80 allowing CP/M to be run, and an 80186.

Thomas Nguyen, CC BY-SA 4.0 There are a few obvious contenders that immediately come to mind, for example both the 6502 from 1975 and the Z80 from 1976 are still readily available.

The Z80 was a bit clunkier with its specialized registers and asymmetries. I did the 6502 to Z80 translation for VisiCalc and expected coding for the Z80 to be easier.

It should have been pretty obvious upgrade path. Commodore should have use this for the Commodore 128 instead of using the 6502 and Z80 CPUs. And the Apple IIgs was pretty much abandone by Apple ...

A team of chip archaeology enthusiasts is making headway on ‘imaging’ for posterity the hugely-influential but now little-understood MOS 6502 chip that almost ...

Modern versions of the original 8-bit Z80 are still sold for embedded applications, making it one of the microprocessors with the longest continuous history of production.

It had a Zilog Z80 CPU and 74LS00 series TTL chips that helped Apple to overcome the problem it was facing with its MOS Technology 6502. SoftCards became an instant success in the market and remained ...