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An Arduino has none of the missing parts you mention (except interrupts), yet it's quite a useful device even in non-toy applications.

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The cortex m0/m3 CPUs most certainly do have breakpoints, svc (trap), interrupts and an optional memory protection unit.

The Atmel CPU is more constrained but still has hardware breakpoints, IO instructions, watchdog timers and interrupt support. It also has far more complex addressing modes (more CISC-y) to save on instruction counts and a variable length instruction set encoding where memory space to store code is a first order concern.

I’m also sure there is a memory controller to control the SRAM.

So, even if you were to build a simple micro controller, you’d need a lot more features and most likely higher performance (and power efficiency) than you would get from a trivial 2-stage pipeline. Not to mention there are no instruction or data caches in this RISC-V machine.

Good point, but unfortunately the focus of the project is only the RISC-V core running in a FPGA. Everything else is already widely available in the internet and can be easily integrated.

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