sean: I saw some weirdities on the data output of the MM78 when it was near the edges of the test voltage range (i.e. 11.5 and 12.5) where it'd seem to oscillate between test mode and operation.
re: cop 411 dumping. I had a hard time trying to get this chip to dump. turns out the damn docs are WRONG! they tell you to use 04h on the LEI instruction (33 04) but then the signals are showing it as 33 44. turns out it has to be 33 64 or else it won't work.
the docs for the chip say the second byte of LEI is 6x, so I changed it and sure enough now data is coming out. I found you can drive the RC input with a regular clock and it works fine, the even mention that this is possible.
The charge dump transistor is very weak sauce so a regular PIC IO had plenty of oomph to overcome it. I checked on the scope and it looks good, no funny business.
The timing on the data into the chip is kinda stupid- you have to input data 0-200ns after the rising edge of SK so what I did was let CLKIN go high, then waited about 15-17 nops, and then output the new data so it occured at 100ns after the rising edge.
This seems to work fine and I got a dump out that repeats every 512 bytes. I am not sure it started in the proper place though, so I was going to poke around with it some more. I ran out of time last night but did finally get data to come out.
Today I received a tandy "cosmic 1000 fire away' and wouldn't you know it, the damn thing has a bastard TI part in it. drat.
Also got a ms pac-man tabletop that I can dump (HD38820) and the frogger tabletop with the mitsubishi micro I will try dumping