Follow that up with Computer Systems A programmers perspective.[2]
My review of ECS [3]
[1] https://www.amazon.com/Elements-Computing-Systems-Building-P...
[2] https://www.amazon.com/Computer-Systems-Programmers-Perspect...
[3] https://www.amazon.com/gp/customer-reviews/RZ4ME4QH22JML/ref...
It explains everything in layman's term.
https://en.wikipedia.org/wiki/S-100_bus
https://z80journal.wordpress.com/2015/10/07/z80-io-space/
Then with x86 PC age, look at the ISA bus first https://en.wikipedia.org/wiki/Industry_Standard_Architecture
and later on, the PCI bus (should I even mention Microchannel?) : https://en.wikipedia.org/wiki/Conventional_PCI
Another direction for computer IO might be to learn about the Raspberry Pi GPIO interface: https://learn.sparkfun.com/tutorials/raspberry-gpio/all
There is a Arduino simulator (I have not used it, others told me about it) on Tickercad.