Personally I like Niklaus Wirth's minimal RISC-5 (not to be confused with RISC-V). Wirth's systems were simple enough to understand from top to bottom, and RISC

Personally I like Niklaus Wirth's minimal RISC-5 (not to be confused with RISC-V). Wirth's systems were simple enough to understand from top to bottom, and RISC-5 was easy to emulate in software or on an FPGA (I also like Wirth's LoLa language.) https://people.inf.ethz.ch/wirth/ProjectOberon/RISC5.Update.pdf https://people.inf.ethz.ch/wirth/ProjectOberon/RISC5.Update....