I do the same for testing dip switches, like on Atari pinball MPUs, turn all of them on, read FF, turn all off, read 00.

Warning - Random blather below:
I am looking at automating the reading of switch matrixes by a simple jumper plug with some diodes. Have the Strobes all going to a separate Return, or , better yet, matrix all the possibilities with a wiring blob (diodes and wire), and then treat the switch matrix as if it was a RAM location in memory. Write AA and then 55 and see if any errors appear. Perhaps a simple ROM chip might help out here, use the strobes as the Address, and the Returns as the DATA. Run a Signature on the "address"? But how to specify the failing Strobe/Return line? Use the Walking bits test? Just some random ideas I'm afraid...

Looking in the Troubleshooter newsletter for an article on checking cables using a pod, for the switch matrix you already have all the select logic you are simply figuring out the test algorithm. Must re-read that more carefully.

John :-#)#

At 10:35 AM 19/06/2002 +0100, Andy Welburn wrote:

> Well how do you do it?

i thought i'd answer on-list :)

hit READ, select the ADDR OPTION to I/O then read address 1

repeat for addresses 2 and 3 for the other input ports..

I didn't check them out fully, however, address 1 is for player 1 controls
and coin/start for sure. Port 2 has the tilt switch.

I didn't bother with the rest as the main things i was looking for were
stuck switches, of which there are none on this troublesome pcb :(

the read result has to broken into its 8 bits, if you read the address, then
hold the appropriate button and re-read, the result will change... its pure
sorcery i tells ya!!

> Thanks,
> Kev

Andy