Home Page Forums MAME MAME TMS-09xx/1xxx thread (was New Dumps)

Checked touch and tell pcb with meter, conclusion is the tms6125 datasheet (1) is right, despite what I've been told by others.
See https://www.dropbox.com/s/e9rrrq9h8t75zcx/2015-12-29%2014.42.43.jpg?dl=0
You can see the tms6100 footprint with the flashlight shining thru the pcb and the tms6125 above that. Pin 1 of both footprints is at the bottom left of each one. note the /CS and VSS of the tms6100 footprint are tied together by a trace.

Also note the 'top row' (pins 15-28) of the tms6100 are n/c inside the package, so ti used that whole row of vias as convenient tie points, they don't actually do anything to the 6100.

BUT. one new thing jumped out at me:
Pin 2 of the tms6100 has a trace connected to it. The tms6100.cpp lists this pin as N/C, and the other end of the trace connects to CD2802 pin 2, the PDC pin. Maybe some early tms6100s required a PDC pulse on pin 2 to accept m0/m1 commands? Or perhaps it was a routing error at TI where someone mixed up pin 2 of cd2802 and pin 2 (which is supposed to be N/C?) on the tms6100 when laying out the board.

LN