I've been trying to figure out how to interface the Canon P170-DH calculator I bought for its keyboard and printer and the discrete-component implementation of the Intel 4004 CPU. Long ago I decided to replace PC board in the P170 with one of my own design hosting an FPGA.
One of my design goals is that the rebuilt P170 should be able to operate either standalone with the i4004 CPU implemented in its FPGA, or using the discrete-component board stack as the CPU. As a standalone device the design is fairly straight-forward. To interface it to the external CPU it need some sort of external electrical interconnect.
It's resolving the nature of this interconnect that has been blocking my design of the new PC board for the P170.
Experiments with the world's first microprocessor
and other electronic explorations
