HP-71B Newbie Questions.

[dhe]

1) How are all the cool kids, transferring software to/from the HP-71B to a modern PC?

2) Is there a hack that would let me run the Forth / Assembler module from a RAM module?

Thanks,
Dan

[rprosperi]

1) To use a modern PC to communicate with the 71B (and 41C/75C and other HP-IL controllers) you need to purchase a PIL-Box from Jean-Francois Garnier, here:

http://www.jeffcalc.hp41.eu/hpil/index.html

Sales were suspended during the Pandemic, however there have been reports that sales would be starting again soon.

The PC (Windows) software, ILPer, available here, provides virtual mass storage and printer.

Another version is also available for use under Python on Win/Mac/Linux here, which provides other features as well, including virtual display, virtual plotter, remote device operation from the PC, and more.

2) No, it's not possible to run the F/A module from a RAM module, as the F/A uses 2 ROMs, a Soft-Configured 16K ROM for the LEX files files (which could be stored in an IRAM/RAM module) and also a 32K ROM which is Hard Configured to run at address E0000 (which cannot be installed in any kind of traditional insert-able module).

However a new EPROM device has just been announced that WILL let you install the F/A, and as a bonus, it's a whole lot cheaper (and more interesting) than a RAM module. See details here.

[hpchris]

Please excuse me hijacking this thread.

I've got a 71B where the batteries don't work (MEMORY LOST).

Using it with AC adapter works fine. Do you habe any idea how to proceed and detect and fix the problem?

regards,
chris

[hpchris]

Or where to send it to for repair? I'm in Germany.

[Maximilian Hohmann]

Hello!

(03-18-2021 11:17 PM)hpchris Wrote:  Do you habe any idea how to proceed and detect and fix the problem?

This sounds like either corroded battery contacts or a corroded connection between the battery contacts and the PCB due to battery leakage. The HP-71B is fairly easy to take apart (see here: https://www.hpmuseum.org/disasm.htm). You probably can do it yourself, there is no big risk of breaking anything.

Good luck
Max

[rprosperi]

Most often when this happens on a 71B, the battery spill has damaged the battery contacts (where they connect to the board) or possibly the zebra connector (though I don't think it would work on batteries if this were the case), but Max is right, it's easy and relatively risk-free to open the case and investigate.

[hpchris]

The battery chamber doesn't show signs of corrosion. So it probably is something in the "inside".

I was using fully charged 1.2V Ni-MH accus. I don't have 4 1.5V alkaline batteries here to test. I'd need to buy some.

Are 4x 1.2V (4.8V) expected to work? 4x 1.5V is 6V which is quite a bit more.

regards,
chris

[rprosperi]

Well, that's possibly a different situation; I would not conclude anything until testing it with 4 known new AAA alkaline batteries. I have read many reports that NiMH cells work fine in a 71B, but have never done that, all my Eneloops are in use in other machines. When I've checked voltage of alkaline cells that 'died' they are typically below 1.2, but I've no idea if the different chemistry leads to different behavior. Fortunately, it's easy and cheap to check, just pick up some alkaline cells, and if it does work with them, please report back here as this may be a useful thing for folks to know.

[mfleming]

I use Eneloops exclusively on my two 71B's. According to measurements made on my own 71B, voltage levels at the card reader power pins for various battery & charger sources are

Charger - 5.55V
Fresh NiMH - 5.38V
Fresh Eveready Gold - 6.04V

I'd be surprised if the problem lies with the NiMH cells unless they're old and close to charge cycle exhaustion. Try measuring them first.

Bob, read the Appendix of the MultiMod manual before running one on Alkaline cells

~Mark

[Dave Frederickson]

There are two cases for the 71. One has a metal back and the other plastic.

The metal-backed case connects the two PC boards within the case with a flex cable. It is well documented that this flex cable isn't very flexible and that handling it can cause cracks in the conductors. This happened to my original 71 which was sent back to HP where they wired the PCB's together.

The plastic-backed case connects the two PCB's with a "golden zebra". While the golden zebra is not affected by cracks, vapors from leaking batteries can destroy this connector and the two PCB's will need to be wired together.

Dave

[hpchris]

It doesn't work with 1.5V alkaline cells either.

Seems I need to open it and debug...

regards,
chris