If you're interested in ARM 32 bit, I can recommend book "Raspberry Pi Assembly Language Programming: ARM Processor Coding"
It very thoroughly describes Cortex M0 assembly language and it also touches the concept of multiprocessor programming. And you just need two Raspi Picos (one to serve as programmer) which are very available.
It very thoroughly describes Cortex M0 assembly language and it also touches the concept of multiprocessor programming. And you just need two Raspi Picos (one to serve as programmer) which are very available.