I did some digging to find out why the IN 020 was giving me 377 (all ones).
I thought there might be a problem with the 8T97 buffers and the SINP signal. So out with the cheapo 10MHz scope (that was a good investment for 150 bucks) and start probing. Hmmm - SINP working on IC S - all good.
But the OUT 021 was working perfectly. hmmm - some overlap on the 8T97 chips between Data In and Data Out - maybe it was the chip enable coming out of IC P (7400) - lets go check pin 8 on IC P -
The only pin on the whole board that I did not solder!!! arrrgh!
Out with the card - solder pin 8 on IC P. Card back in, hook up computer to serial. Develop more finger calluses toggling in the echo program. Voila! It works! Now on to loading Basic. I've got 5K installed, what will happen with 4K basic? I guess the memory space is set by the loader? Or is is hardcoded in the basic tape?
Thanks for all the help
Cheers
Kelly