Help with HP-20S needed



today I got a HP-20S. Unfortunately its manual is not on the HP-Museum CDs.

I think I can figure out how to operate most of its functions myself. (Even if I am nearly unable to calculate with an algebraic machine by now :-)).

A feature I could not get to work is the LOAD key. I know that I can copy some programs from ROM with it. But how??

Can anyone help me?

Thanks! Holger


enter program mode, press load, then press one of the letter's on the top a-f, you will see a quick message stating the program loaded. It is also possible to download a manual for the hp20s in spanish off hp's support web site.


Thank you, JaSon! That helped.

The manual wouldn't be very useful for me, since I don't speak spanish. I wonder why HP publishes it in spanish but not in other languages...



Perhaps because some good spanish can translate for you some parts that you need (if they are not very long ;-)

Regards from Spain


If I find the time I will scan the manual. But email me and I will send specific pages to you if you let me know of any functions you patricularly need.

Gordon Dyer


Hello Gordon,

thank you very much for the scanned page you sent me via mail! I'll have to find out now how to use the built in programs, but I hope not to need any more pages for that.

Nevertheless - if you have scanned the whole manual one day, please let me know. Maybe it could also be published here now since the HP-20S seems to be discontinued. (Don't know the details of Dave's agreement with HP concerning obsolete manuals).

Best regards,



Craig Finseth has a complete but concise description of 20s:

I used this for learning how to use my wife´s 20s


>> since the HP-20S seems to be discontinued.<<

As an algebraic programmable scientific calculator, the HP-20S is a surprising good quality built device by Hewlett Packard. We get three of them at home without manuals, two for kids (really love this model more than the 6S, they've got before) while keeping one for myself.
Prices are reasonnable for now but start rising soon I guess !


It's been discontinued off and on, it seems, but finally permanently now. I'd like to personally find some of the corporat elogo OEM ones.

In general terms, the supply of old style (orange and blue shifts, brown case) ones is still okay. I've gotten a few here and there. there are a lot of warranty replacement (no manuals or slip covers) for ~$20 available right now.

The red box ones were available from some overstockers for ~$20 US in the past, but that seems to be fading. I doubt these will be costing $100 anytime soon, but $50 could happen.

I've written a few things (including a "boy scout" encryption system) for it and it's quite programmable within its limits. I'd prefer 4 real stack registers and direct access to them instead of the input/swap thing, but even as it is, it's an amazing amount of power for $20. The really early HP programmables didn't do much, if anything, more than this can.

Another one of those areas where just a little bit more would have made all the difference (16 or 20 registers, 150 or 200 steps, a better implementation of the input/swap thing.) Why do we keep getting LESS instead of more?

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