I forgot I also have a working Stop Thief.
I can't find an oscillator output on any of the TMS0980 pins, though. I used an oscilloscope to measure the pulses on pin 14 of the chips, and found that when the TI30 is first turned on and displaying just 0, that pin 14 has a period of 5.8mS. When Stop Thief is turned on and displays "1 Cr", pin 14 alternates between periods of 7.0mS and 9.1mS as the display blinks.
Doing informal count comparisons, I estimate the TI30 emulation takes nearly 50% longer to do calculations than the real unit.
Also, for some systems, I can not exit the emulator screens in MESS 157 without doing an alt-tab, then right-clicking on the icon in the task bar and choosing close window, which returns me to the MESS menu to select another system. I can hit escape from any of the information windows that pop up when I select a system before it starts running, but once some systems are running, I can't find any keystrokes to return to the menu or select controls. This is on Windows 7 Ultimate 64-bit, running MESS64 from the command line.
For example, tab and escape work in Merlin and Simon, but not in TI30, Speak and Spell, Stop Thief, or Wizatron.