
   Spy vs Spy

This game has problems with working at 60 Hz
refresh rate (NTSC), so added code to switch
to 50 Hz at start. Of course needs TV/Monitor
capable to work at that refresh rate.
Don't see other solution, because game code
is not enough good to work on different 
refresh rates, and it works bad on CPU
clocks higher than 8 MHz too.

  PP, Jan 2021.
