I played around with it, and it's very neat. This is the first time I've seen an assembly REPL and I wish I had something like this that ran native for playing with unfamiliar instructions.

I did find a couple minor issues with the simulator: MVN is supposed to be a bitwise NOT but the simulator does a two's-complement negation instead (https://github.com/rtybanana/irisc-web/blob/main/src/interpr...), and it seems negative immediate offsets aren't supported, e.g.

  ldr r0, [r1, #-4]