I am planning as an exercise to learn Verilog to implement a CPU core. As this is my first time doing it, I am wondering what would be the simplest CPU architecture with a currently supported toolchain that could be implemented.
The list of supported architectures can be seen here:
I learned about the ZPU which is extremely simple but the compiler support is outdated (need to compile a very old gcc from sources).
MSP430 ISA contains just 27 instructions. There are multiple toolchains around, original one from TI as well as msp43-gcc and MSP430 support in LLVM/clang.