Connecting a Z80 to a Raspberry Pi

I have a long history with computers, starting with a Sinclair Zx81 that I still own, followed by other models and others that I wished for, as time went by.

A while back, I found an old box with some old processors, x386, x486, a few Pentiums first generation and two Zilog Z80. Then I got a kind of retro-feeling in my mind and I watched some YouTube videos about them. One of them was the classic nop-test, I had fun with this for a whole afternoon.

Then I decided to do something more fun and try to connect with a raspberry pi. The pi should act as the rom/ram and IO system.

What I did, was link two mcp23s17 to the pi using SPI and this to the address and data bus on Z80. Of course, control signals, reset, m1, mreq, rd, wr, ioreq and clock.