HP 71B Ports

[J-F Garnier]

Yes, I also tried the dual HP-IL adapter without thinking about it. But it can't work: standard front port module don't provide the configuration daisy out line, so the configuration of the 2nd module inside the HP-IL adapter is not done correctly (contrary to the HP-IL modules that *do* provide the configuration out daisy line - the multiple HP-IL adapter was considered at HP-IL module design).

A bad configuration can lead to a severe HP71 lock-up as you are experimenting. In the past I got a few of these severe lock-ups, that can be difficult to recover, even by battery removal for several hours.
My way to recover is: remove all modules, remove battery, *short-circuit* the HP71 power lines not at battery terminals because there is a diode in between, but at the card read port connector (the first and last pins).
Several attempts may be needed to recover. Each time you insert the batteries without success, you have to restart the process.

J-F