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Full Version: HP41CX overlays and HP-IL (long)
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My first question is pretty basic, how were the blank keyboard templates packaged and sold by HP? I'm trying to hunt some down and thought it would be easier if I had a part number or something. Alternatively, if anyone has a pile....

Second: I'm attempting to "upgrade" my old VW van. (VW's are very hackable) It currently has a mounted tadpole laptop and some assorted connections for sound and cd playing, but I'm thinking of adding an onboard loop.

Regardless of the control device (which will be either a 41 or a 75D or both, be even better if I can find a 75 no D somehwere)-

1. What ideas does anyone have for actual useful stuff to do? I've got ideas for light and accessory controls (this is a "westy", the camper version), some data recording (mileage, gas, oil) and maintenance tracking, and perhpas an interface to stero controls (that's very tough, as I would have to build and HP-IL/IR converter and decode the IR remote, or bypass the wiring for it at least.
While this is all about fun and making the van more worthy, I would like to point to actual uses. And I'm aware that I can do a lot of this easily with PC hardware, but I'm exploring low power use options and smaller scale buildouts.

2. I am not quite at a level to design some of what I want, and I'm not familiar enough with all the hp-il and 41 books out there to know if there aren't some plans for this. I can assemble most anything short of small SMD hardware (I tried, I'm sloppy, or I need a good temperature controlled weller instead of my voltage controlled stuff), and I know the theory of what goes on inside, but that's about it.

3. Not specifically for this project, but as a possible add on, I'd like to know if anyone ever did any work on controlling telescopes via HP-IL. I cna see ways to tie existing equipment into the 48 series, though I'd have to get all the pinouts sorted. (I know some models are controlled by rs-232)

4. Definitely related to this project, is it plausible to make an HP-IL to rs-232 conversion box cheaper than the $200 they seem to be selling for on ebay all the time?

(I've considered HP-IL over repeeater net, too. But I hav e no idea what I'd do with it)



do you mean


Best regards


good luck on the rebuild - just don't change the sticker on the back window.

nah, the sticker stays. I may make an HP41 sticker to go beside it, though.

The data tracking codebase is fairly simple thus far, I think I'm going to start having that in there and add the HPIL devices "as I go".

Is there any set of plans or documentation floating around to build an RS232/HPIL interface?


> Is there any set of plans or documentation
>floating around to build an RS232/HPIL interface?

maybe Christoph Klug could be able to answer you on this question...



Dear Christof,

it seems that Raymond Hellstern gives you the best response !

Much better than the IL/RS232 Interface is the HP82166A IL-Converter for hardware interfacing. For this device I developed two powerfully interface systems called I/O-Board and IL2000 system. Both are battery powered and includes the needed control input/output lines you need for your exotic car interfacing project. Also detailed documentation including HP-41 software routines and hardware circuit diagrams is availlable. Take this proved plattform and finish your application in short time !

Best wishes from Germany - Christoph