A Pac Man board can be modified to a Ms Pac board by removing the ROMs in the 6 th row & perfoming the following
hack. You must also change the 2 character ROMs at 5E & 5F to Ms Pac character ROMs.

Chip @ 7N is the program Rom chip select decoder. A15 is added to 7N pin 13 and output pin 5 becomes chip select #5
(6M) and pin 6 becomes CS #6 (6N).

All the boot Ms Pac images can be combined in a single 27256 Eprom and the board retrofitted to run this by.... 

     1) Add 28 pin socket into 6J with pins 1, 2, 27, & 28 exposed. Also bend pins 20, 22, 23 & 26 out horizontally (so
     you can solder wires to them) and press the socket firmly into the PCB socket at 6J. 
     2) Tie pin 23 to 7L pin 9 (A11) 
     3) Tie pin 26 to 7N pin 14 (A13) 
     4) Tie pin 2 to 7N pin 15 (A12) 
     5) Tie pin 27 to Test Connector pin 16 (A15) 
     6) Tie pins 20,22 to 7N pin 12 (Chip Enable) 
     7) Tie pin 28 to +5 VDC 
     8) Tie pin 1 to GND. 

You may use a 27512 chip to hold both the Pac & Ms Pac images (or speedup/slow) and toggle between versions by
following the above steps but after step 7 begin here.....

     8) Tie pin 1 to 8H pin 2 & cut trace away from 8H pin 3.

this uses the cabinet test switch as a toggle between software versions. If you would rather not do this you can simply use a
single pole double throw switch (SPDT) Tie the center pole to the 28 pin socket pin 1. Tie one side of the switch to +5 & the
other side to GND.

If you are toggling between games that use different character/maze ROMs (such as Pac Man & Ms Pac Man) then you will
want to add a bigger EPROM to hold both images & make this switch able along with the game code. To do this use a
27128 

     1) Add 28 pin socket into 5F with pins 1, 2, 27 & 28 exposed. Also bend pins 20, 22, 23, & 26 out horizontally to
     solder wires to. 

     2) Tie pins 1, 27 & 28 to +5 VDC. 
     3) Tie pin 20 to GND 
     4) Tie pin 23 to 4D pin 2 
     5) Tie pin 26 to pin 1 of 6F (the switch) 

Originally this hack included a 7408 piggy backed to 5N with....

1) pin 1 to 5L pin 5 & 5F pin 2 2) pin 2 to 5L pin 7 3) pin 3 to 5F pin 22 BUT I suspect that you can just make the CE
active by tying pin 22 to GND