Hi gslick
I'd be very interested by a schematics (I read this thread but I have a difficulty to transforl the text into something that I could build).
Did you by chance scan the manual ?
Thanks !
I have an original copy of this manual, which includes a schematic of the preprocessor interface:
Model 64683A Interface Module Z80
Service Supplement
HP Part Number 64683-90903
I'll have to get my scanner set up again so I can scan it.
The main thing is that all of the Z80 CPU signals are buffered through either 74LS241 Non-inverting Octal Buffer and Line Drivers, or 74LS240 Inverting Octal Buffer and Line Drivers.
The complication for using the original Z80 Inverse Assembler is that the CPU PIN 22 /WR signal is inverted (routed three times through a 74LS240 Inverting Octal Buffer and Line Driver) when used as STAT Bit 0. If the logic analyzer is attached through flying leads instead of the preprocessor and the /WR signal is not inverted, the original Inverse Assembler will not function correctly.
The original Z80 Inverse Assembler could be modified to work when the /WR signal is not inverted when used for STAT Bit 0. If I have never posted details here on how to do that, I'll have to do that when I make some time to do so.