the 595 loading code worked on the first try
The ‘595 loading code worked on the first try, which I can explain only because I found the cascading shift-register logic unintuitive at first, until I realized I got to make up the rules about endianness, data/address order, etc., and at that point I had the whole sub-project fully in mind. Usually a great time to bang out a few dozen lines of code!
On the screen you can compare the bytes to be loaded ($12, $12, $12, $0e, $fe) with the lower nibbles implied by the logic analyzer ($2, $2, $2, $e, $e) and confirm they match up. I haven’t tested the address lines yet. We’re getting close to hooking up ROM (or SRAM that’s not writeable) to the ‘09!