I wrote a program called xtce-trace (<a href="https://www.reenigne.org/software/xtce_trace.zip" rel="nofollow">https://www.reenigne.org/software/xtce_trace.zip</a> ) to do just this (albeit non-interactively - you just give it a program and it will generate a cycle-by-cycle trace of which lines of microcode are executed). GloriousCow aka Daniel Balsom recently fixed some of its bugs and turned it into an actual emulator (<a href="https://github.com/dbalsom/XTCE-Blue" rel="nofollow">https://github.com/dbalsom/XTCE-Blue</a> ), though it's not finished yet so there's no binary release at the moment.
xtce_trace sounds fantastic — exactly what I need right now while debugging my Verilog 8086 core. Thank you also for the microcode disassembly. It’s been fun to work through.