I used to explore what happened reading/writing to memory locations connected to the expansion cards on the Apple ][. I later had a Spectravideo PC and one of t

I used to explore what happened reading/writing to memory locations connected to the expansion cards on the Apple ][. I later had a Spectravideo PC and one of the first things I did was explore the memory by writing into different locations to see what happened. I also wrote a Z-80 disassembler to try to reverse engineer how much of the system worked (unfortunately, I never got around to properly decoding multi-byte opcodes).