HP41.org

Is there anyone out there who has (1) a working HP 82104A magnetic card reader and (2) an HP-41->PC connection who would be willing to receive 6 magnetic cards by snail mail and email back a very useful program? I'd like to provide it to hp41.org, as well as having a copy on my iPhone (now that I'm rediscovering the wonderfulness of the HP-41 with an emulator).

I wrote a very useful program EIGEN that computes eigenvalues of order 2, 3, 4, and 5 matrices -- this functionality is not available in the existing libraries (I see order 3 and 4 in separate packages, but no order 5 -- order 6 is probably beyond the HP-41's limited memory).

My problem: the program ONLY exists on a single backup of 6 HP 82104A magnetic cards. I just attempted to read the cards, by my old card reader has "gooey roller syndrome" and will not read cards.

I could attempt to repair the card reader's O rings, but now, the only use of this reader is to get a copy of the EIGEN program, and it would be MUCH easier if some kind person would be able to read and email the code. Once this is done, I'll provide it to hp41.org.

Please let me know here, or by private email visible on my profile.

I would help, but I don't know how to connect my HP41CX to my laptop.

Thanks -- do you have a thermal printer? I'd just be happy for the printout.

I see that there are two good online descriptions on how to repair the gooey roller syndrome here and here:



I'll pick up a model airplane fuel line and try to fix this myself. If I fail, I'll come back and make a standing appeal for help. Wow, this is really a different world from the iPhone! But I really doubt I'll be attempting to repair an old iPhone in 25 years.

P.S. to hp41.org admins: I suggest archiving the HP 82104A repair information for "gooey roller syndrome" on the websites here and here, in case these ever disappear.

Sorry, I don't have a printer. I've been looking for a 82143 on eBay. So far no luck.

Well that was easy. I just stopped by a hobby shop for a fuel line, followed the repair instructions, and now have both a working card reader and working code -- eigenvalues and the characteristic equation for matrices of order 2, 3, 4, 5. Looking back over my cards, I also see that I have a ERF and ERFC function, and other stuff too. Amazing machines that this stuff just works after all these years.

Now the question is: what's the easiest way to get the code off my HP-CV? There's 814 lines of code for EIGEN alone that I'd really rather avoid re-keying and re-checking.

Is there a reliable, low cost jury-rigged HP->USB connection that has a low probability of frying my HP?

If you can locate an IR printer module and an HP48 you can print and capture the program on the HP48 using a program called INPRT (or something similar). Then transfer the text file to your computer using Kermit.

This was a new method for me to transfer programs from 41 to PC. Are you sure that this works.

Sure, works fine, I have transferred programs this way.

The IR receiver in the HP48GX is a bit crippled so you need to line them up carefully, but once you done that, it transfers just fine.

However, you get it as text, not binary, so some lines do not print so good, synthetic texts for example. You need to tidy that up afterward.