HP 71 - serial interface

[Karel Kupka]

Hello. Does there exist any interface or cable for HP 71 or HP 41 to send and receive data via RS232 serial link (with 9-pin Canon connector on the other end)? And of course any program or system command support like OUT and IN on the respective device?

[Emmanuel, France]

[pre]Dear Karel,
I only know two interfaces:
HP82164A made by HP,
and one made by Hand Held Products (32k buffer & autopowered).
;o)
Emmanuel [pre]

[Garth Wilson]

Add to that the FSI164A from Firmware Specialists, Inc., which is virtually 100% compatible with the HP unit but came with two RS-232 channels and optionally up to 8, and also offered the option to go battery-powered. Mine is only two channels and not battery-powered. I've used it a lot with both the 41cx and the 71B. A scan of the manual (actually mine) is available on the HP-41 website.

There was a way to make a serial port on the 71 by soldering a couple of wires onto uncommitted I/O pins on the processor IC. (There would not be any line drivers or receivers though.) It doesn't seem to be in the book "Control the World With HP-IL", so maybe it was in one of the CHHU Chronicles. It would take me some digging to find it. I definitely would not risk damaging either of my 71's though when they both work 100% like new and there's no support for them anymore if I damage anything.