The 6502-based BBC Micro had this in the 80s as the Tube. This could run a Z80 and other processors. The interface was initially used in the development of the

The 6502-based BBC Micro had this in the 80s as the Tube. This could run a Z80 and other processors. The interface was initially used in the development of the Arm processor: https://en.wikipedia.org/wiki/Tube_(BBC_Micro) https://en.wikipedia.org/wiki/Tube_(BBC_Micro)