I am making my own serial cable ( USB to serial TTL ) to flash the HP-30B with the WP-34S firmware releases when needed.
The USB to Serial converter is based on a Prolific PL2303HX.
I using an additional 3.3V regulator based on the DS1117-3.3 IC as a source voltage to the calculator power supply, Reset and Erase functions of the serial cable.
The only missing part is the cabling terminated with six pogo pins to connect to the calculator.
The following (shaky) video shows the prototype in action.
The serial interface is connected in loop back mode.
I am running the Hyper Terminal on Windows to send and receive ASCII chars from the keyboard.
Prolific PL2303HX USB to TTL serial adapter:
