I found working with relatively simple 8-bit microcontroller architectures (e.g. Atmel AVR, Microchip PIC), studying the datasheets and programming them in asse

I found working with relatively simple 8-bit microcontroller architectures (e.g. Atmel AVR, Microchip PIC), studying the datasheets and programming them in assembly, to be an effective and gratifying introduction to the basics of CPU architecture.