from a friend I've got a modified ROM for the Sensory Chess Challenger (SC9), it is from a tuned (8MHz) machine.
It is indeed very similar to the version implemented in MAME (by 'hap'), it has the same size and the same ROM addresses, and essentially it's working.

There's only one big problem:
it only responds to mouseclicks on the 8th row of the chessboard (a8-h8), all other fields are simply ignored. frown

I've now already tried to solve this problem for many days, but unfortunately without success. The current routine 'sc9_input_r' in the SC9 driver is
	return read_inputs(9) ^ 0xff;

and I've changed this in many different ways, but nothing worked.

Has anyone any ideas what else I could do (or try) to solve this problem?
Is there any method to find out what exactly the device expects to get from from the driver, when you click on any sensor field of the chessboard?
Or are there any other places in the driver that could be the reason for this problem?