I don't know how much matches the ZX80/81, but on there, port $FE (and all other even ports) read as
* D0-D4 are the keyboard columns
* D5 is not used
* D6 sets 525/625 lines
* D7 is ear input from the tape.
In this instance D6 is the input from the tape, I realise. Tape/kbd interface (LS244) is controlled by /RD plus output from an LS139 toggled by A11/A12.
I’m sure I’ve run the machine with that chip removed though. Time to sample that 244!
Comments
* D0-D4 are the keyboard columns
* D5 is not used
* D6 sets 525/625 lines
* D7 is ear input from the tape.
I’m sure I’ve run the machine with that chip removed though. Time to sample that 244!