Well, I've been trying to interpret the coding to the Pod from the base unit using a really nice software/hardware tool called SoftLA. Software Logic Analyzer is what it is, 16 channels! You can get it from www.BGMicro.com for about $30US.

See http://www.bgmicro.com/pdf/page14.pdf for a write-up.

Now when I set up the base and pod and have the SoftLA monitor the POD 0 - 7 and MAINSTAT, PODSTAT, RESET, POWERFAIL, and also monitor Chip Select (pin 23)  & ENable (pin 25 - normally Phase 2) on the select side of the 6520 PIA I get some curious results.

If I tell the Pod to do a BUS test, and I use CS as the trigger point I get a RESET BEFORE the 6520 is SELECTED...psychic...it knows it is wanted. Is anyone here more familiar with the programming ins and outs of the 6520? I think FLUKE might have used an undocumented (in my reference book by Rockwell) data call to the PIA that seems to enable PORT A to output data WITHOUT the CS or EN.

If the PIA is only communicating when both CS and EN are set, then there aren't that many instructions...if it is when there is some sort of chatter via PORT A that does NOT involve CS or EN then I think some disassembly of the base code is going to be required...Gah!

John :-#)#