Originally Posted By seanriddle

I haven't been able to get the (assumed) TMS1000 from Sears Follow Me to electronically dump. It acts like it's working, but every byte in each page is the same, although each page is different. So it looks like it's not clocking in the program counter correctly for some reason. I've tried different voltages and I adjusted timing in my program.

I finally got the chip to dump. When you clock a TMS1x00 in reset, every 6 oscillator ticks the O7 output toggles. You shift in the 6-bit program counter and parallel load the chapter and page based on the tick, so you use that O7 pulse to sync up. This chip synced one pulse later than all the other ones that I've dumped. Once I accounted for that, I was able to dump the lower 7 bits, then execute each address and shift out the program counter to get the high bit.

There were 10 ambiguous bytes where the lower 7 bits were the same as the next value of the LFSR program counter. 6 of them turned out to be branches.

I decapped the chip to see if it was a different die revision, but it is a TMS1000 rev B.