Hello
I tried to repurpose my HP 30b but was able only to ERASE firmware. Failed all attempts to connect via Sam-BA. Looks like there no clear picture of HP 30b serial port pinout. I found in some message:
J35 - GND J33- TxD J31 - Vcc
J36 - ERASE J34 - RxD J32 - RESET
but according HP 20b schematics:
J35 - (calculator output) J33 - (calculator input) J31 - Vcc
J36 - ERASE J34 - GND J32 - RESET
Who knows the truth ?
Thanks in advance!