If anyone wants to try it out, I just committed my CPU core and driver for the Manchester Small-Scale Experimental Machine (SSEM), or "Baby", to the MESS SVN depot. It currently runs all known SSEM programs bundled with David Sharp's SSEM simulator, available here
I am not entirely happy with the fact that it is compatible with all of the programs, though. Certain programs in particular, i.e. "nightmare.snp", would not run on the SSEM had it ever been extended to the full 8192 words of storage space of which it was theoretically capable (per some SSEM history sites), as they pad out the unused 8 address bits with pretty patterns.
Edit: Pretty picture:
The controls are as follows:
Up / Down: Move the selected store line up/down
Button 1: Halt / un-halt the SSEM
1-8, Q-I, A-K, Z-,: Toggle bits 0-31 of the currently-selected store line