HP-42S/41 programming info


Hiya folks,

I just added a 42S to my collection (35, 34C, 15C), because I couldn't pass up the great price at a pawn shop. Of course, at the price, there was no manual or case :-( I have ordered the HP Museum CD set so that I can get a manual to use the calc to its fullest -- but in the meanwhile, I'd like to learn a bit about it. It's rather different from the programming interface on my 15C in some respects, so I've only been able to find a few of the more obvious features by poking around.

Is there a "quick reference" for this or the 41 that I could peruse to get my feet under me until the CD set arrives and I can refer to the real manuals? A web search came up with nothing directly related, and I'm not totally clear on the programming differences between the 41 and 42 (other than memory and display size, of course).

Also, does anyone have a suggestion for a protective case substitute? I don't want to put any unnecessary wear and tear on the calc while carrying it around.


I have only been fortunate enough to own a 15C, 41CV, 28S. I don't know the true usable value of the easy to carry 42S, but I know one thing I would do if a had one.


The cheapest you will find them on the forum is $250, for the few that are for sale. Carrying one one anywhere outside the home is, in my humble opinion, asking for it to be stolen.

Please listen to the pleas of one who could give it safe and comfortable home. If you plan to open it up to theft at the hands of some unsrupulous vagabond in the cold cruel world, send it to me and I will keep it in my 1/2 hour at 2000 degree fireproof safe.


Hehe. OK, plea noted. I didn't mean that I was really going to haul it around with me all day; but I hate to leave it sitting out and open to dust and cat abuse, either. ;-) Maybe a jewelry presentation case would be appropriate?


The slip case is still available through HP as a replacement part for the 17BII. IIRC, they run about $8 through HP Parts Direct (800-798-5487 or www.partsdirect.hp.com). Ask for part #82243-60001.

As for programming support, well, you could always look through the HP-41 programs on this site and key a few of them in, just to get a taste of it. Anything with Synthetic instructions (probably) won't work and key assignments don't work the same way, but most of the instructions are identical.


In my humble opinion the 42S is the best non-graphic programmable calculator. Programming the 42S is much more easy than 41. Functions are avaliable menu form and they become active when you choose shift and numeric keys and math keys. To start a new code just press shift GTO .. (2 points) and shift PRGM
You can assign functions, programs, variables to the customs menus using shift ASSGN and choosing one of the 5 upper keys corresponding the position of you want to assign.
I use my 42S since '87. I designed many structures using it with codes I wrote for continuous beams and slabs.
You can do many things with it, just don't worship it. It's just a calc machine!


Yeah, I sat down last night and keyed in a couple of programs. It wasn't too bad, but the menus and reorganization of the program codes were a little confusing at first. Now that I know which keys bring up menus in PRGM mode, and where all the statements are located, it's a bit easier to work with. Some of the function names are subtly different from the 41, so I had to experiment once or twice to figure out what things like "MVAR", "VARM", and "PIXEL" meant. :-) I can't wait to get the manual on CD.



The PIXEL function turns on a single pixel in the lcd display. The coordinates are given by x and y registers.Before you use this function you need to clear the display using CLLCD.
Try the code, the underline separates the code lines:

01 LBL"PIX"_
03 LBL 01_
04 RAN_
05 100_
06 X_
07 IP_
08 RAN_
09 100_
10 X_
11 IP_



The PIXEL function turns on a single pixel in the lcd display. The coordinates are given by x and y registers.Before you use this function you need to clear the display using CLLCD.
Try the code, the underline separates the code lines:

01 LBL"PIX"_
03 LBL 01_
04 RAN_
05 100_
06 X_
07 IP_
08 RAN_
09 100_
10 X_
11 IP_
13 GTO 01_

Run code using XEQ PIX and exit infinite loop pressing ON key

The function MVAR and VARMENU are used together for input forms, try the code:

01 LBL "VOL"_
02 MVAR "A"_
03 MVAR "B"_
04 MVAR "C"_
06 STOP_
08 RCL "A"_
09 RCL "B"_
10 RCL "C"_
11 X_
12 X_
13 "VOL= "_
14 ARCL ST X_ shift ALPHA RCL . STX_
15 " M3"_ shift ALPHA ENTER, creates a t kind char that add strings_

Run code using XEQ VOL and enter the data in each var menu.Tip-->holding shift key + the menu var key you can check the variable value.


Heh. Those are pretty cool programs. But the display isn't 100x100 pixels; does it wrap around, or what?


Only The Lord is perfect.
I just wanted to show you an example. You can improve the code for turning on only the existing dots in lcd (131X16).
The dot (1,1) is the higher left corner and the dot (131,16) is the lower rignt corner.
I guess you should try.


Wow. I was into the system, placed my order and out again in 5 minutes. HP rules. :-) It was a mere $6.00 for the case, including shipping. Thanks!


You're welcome! Glad to be of service.

I agree about HP's parts supply system -- to a point. When it works, it works well. When there is a problem, however, it is a nightmare to try and find somebody to answer your question. I've been trying for several weeks to get an F1011A-ABA AC adapter (aka F1011-60901) for my 82440B thermal printer. Both of the HP consumer shopping groups are pointing at Parts Direct, saying that I can buy it through them, and Parts Direct is pointing back, saying that they don't stock it. Meanwhile, Agilent has the same part (F1011-60901C) for sale, but they refuse to sell it to me, referring me back to my "medical equipment supplier". Grr.

When I finally did find someone who claimed to have some knowlege of the part, they told me it had been replace by the F1307A-ABA. So I bought two. At $34.99 a pop. And they don't work. The connector is the wrong size and the output is 5.4V instead of 12V.

Anybody need a spare adapter for an Journada 3xx? I can make you a good deal... :^/


Oh come on... Probably the biggest reason the 42S sells for as much as it does on this site and on eBay is because it is an easy to carry calculator that provides all (or most) of the functionality you'd want in a programmable engineering calculator. While you can certainly stick your 42S in a display cabinet (or in your fireproof safe) it seems like a waste of a calculator whose true value is in it's functionality.

$250 is actually not that big a deal -- I bought a new HP41CX at my university book store for $325 in 1985. Over the following years I paid list price for several modules, a printer, mag card reader, etc... The only reason $250 seems high to me now is the 42S sold new for $120. When my 42S bit it last year, getting a relatively new one on eBay was still more cost effective than other alternatives.


Kevin FitzGerrell
Systems Engineer
Foxboro New Zealand


To clarify for those who cannot read between lines:

I agree that a calculator is just a tool. But certain tools have greater value due to design and/or capability (case in point: 15C). When you find a good tool, you must also consider its replacability (do they make or replace it anymore) and theft attraction (wow! an unattended 42S! cheaper than buying one!). My daily use 28C is old and showing signs of dying, which prompts me to buy a newer replacable model to keep RPN and infinite stack on screen with service if needed.

My plea was more for reasonable care, feeding, and protection, even if that means firesafe protection when not in use if the tool is so valuable.


I have a stupid question but why did hp drop the 42s and keep the 32 it seems the 42 could be fabricated for about the same cost?


You ask a question that many HP enthusiasts would like the answer to. Only HP could answer, and they have been less than responsive to requests for a re-introduction of the 42S or introduction of a suitable replacement. Obviously, production cost is not an issue. The likely reason it was discontinued was that it did not "fit" into the product line. HP probably considered it a little too advanced for many users. More importantly, HP probably thought that it also took sales away from the 48 series by presenting a calculator that was very powerful, yet compact. HP took it out of their product line to force high-end users to the 48 series, and left the 32SII for the rest.


I was in an office superstore today and there is nothing like the 42s or the 15c. All the top end scientific calculators are simply gigantic. Is there not enough of a market anymore for something like one of these?


RPN is the best anti-theft feature around. Be sure to encourage any questionable characters at work to try out your calculator in your presence. If s/he can use it to add two plus two, regard that person as a threat. Otherwise, the "confusing" interface will cause her/im to write the calculator off as worthless! (This only partly in jest . . . )


Did anyone suggest a hard plastic case for your 42s? I've been using one for years
and this case has saved my calculator more than once. I'm in construction and use
my calculator out in the field every day. The case protects the 42s from falls and
also the lid flips backwards and converts into a "table stand" for the calculator. I
can't quite remember the name of the manufacturer, I think it was Astech. They
make the cases for the 42s which also works for the 20s. I'm sure someone out
there knows the name of the manufacturer and where to get the cases.


Hehe. Right after I posted the message about getting the case, too. :-)

Yeah, I'd be interested in a hard case for the 42S. I'd also love to know what to use for my 34C, too; it needs to be protected from dust and casual knocking about if I'm going to keep it in a nearby drawer for occasional use...


On Wednesday, after receiving the info about the HP-42S case part number, I set up an account on the HP parts ordering system and placed an order for the case. This took all of about 5 minutes.

Friday when I arrived home from work, the package was waiting on my front door step. Viva HP!

It's rather a tight fit, though; guess I'll have to let it strtch out as it gets used to being filled by a wonderful 42S. :-)

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