Eric Smith - I Need Your Help - HP41C


Hey Eric (or anyone else that may know),

I am trying out the Hp 41C Memory Testing program you posted here last week.

Line 38 of the program reads: x/=y?

I assume this means "x not equal to y?", which is indeed a conditional test listed on page 171 of my manual.

However, I cannot find any way to invoke this conditional test. It is not on the keyboard (nor are the < or > signs available in ALPHA mode as far as I can tell), I cannot find instructions in my manual on HOW to execute it (the manual sinply lists the fact that it exists) and I have tried hundreds of different keystrokes without hitting upon the correct one.

Please help me. I hope you will excuse my ignorance on this issue as I am very new to the HP 41C.

Thank you.

Take care.



I assume this means "x not equal to y?"

Yes, that's correct.

However, I cannot find any way to invoke this conditional test. It is not on the keyboard (nor are the < or > signs available in ALPHA mode as far as I can tell),

The angle brackets are the shifts of I and J (COS and TAN).
The not-equals symbol is the shift of H (SIN). These
should be shown on the label on the back of the calculator.

Let me know how things go. I hacked that program together
very quickly and only gave it minimal testing, but I think it works.


Thanks, Eric.

I'll go try it now.

I think the back of the calculator is the only place I DIDN'T look to try to figure out how to type in those characters. I feel kind of silly now.

Take care.




I know all "veterans" know about this, but it's just a matter of finding the best moment to post about.

The HP41CX back label figures the CX-exclusive [ED] keyboard. It's different of teh one found in both HP41C and HP41CV. In this case, both back labels figure the "/=" (not-equal-to) symbol, but some shiffted functions are changed.

My 2¢.

Luiz (Brazil)


Thank you Luis,

I really like my 41C and am actively looking for fullnut versions of the CV and CX to add to my small collection, so I am eager to learn all I can about all of them.

It is slow by today's standards, it doesn't have equation lists or a SOLVE feature like some of the later models, but despite these shortcomings I am starting to think the 41c series is the best calculator HP ever produced. It definitely has the best heft and "feel" in your hand (I think substantial is the correct word).

Take care.




The program runs, and displays "STO OK:###", then stops. When I hit R/S again, it kicks out of the program (usually with the number 25 displayed).

I assumed hitting R/S would start the "RCL OK:___" test. Is this what the program was supposed to do?

I have checked several times and I'm pretty sure I have it entered axactly as you posted it. i will check again, though.


Take care.



Hello, Wayne;

I hope you forgive me posting instead of Eric (and I hope Eric forgive me, too), but I think there is no problem on what you're getting after you press [R/S].

I don't see Eric's listing, but there is one fact we probably agree with: unless the circuits are faulty, you can either use [RCL] or [STO] to make sure a register exists. If you use [RCL] instead of [STO], you'll change stack contents unless the register you recall the contents from does not exist. You probably have one or more [FS? 25] or [FS?C 25] instruction somewhere in Eric's program to detect the occurrence of a "nonexistent" register. When this happens, the program stops and shows a compreensive message, like "STO OK:###".

I guess you typed the program in and you did it without using any specific "synthetic" procedure, I mean, only regular keystroke sequences. So I must tell you that the HP41 has a "standard" behavior when you run a program: the program becomes the "current" program. if you run a program and right after it stops you press [PRGM], you'll see something like this:

[00 .REG. ### ] (if you press [SST] you can navigate)
[ PRIVATE     ] (protected program; can't navigate)
[00           ] (ROM program; can navigate but alter)
It's not unusual to start running a program and stop somewhere else; in this case, you can also see a step number and some mnemonics after pressing [PRGM], meaning the program actually stopped somewhere but the last step (an END). The fact is that the "current" program is completely available to be edited if you press [PRGM] (unless it's a protected program or a ROM program). The best procedure to position the "calculator" (i.e. program counter) in an unused part of the available memory is pressing:
after you finish using any programs. You might do that only when you are not running programs taht compuse a particular computation that's still being performed at the moment, because [GTO][.][.] sets some internal pointers to default condition, and also clears some internal references like subroutine return addresses, if applicable (and if I am not wrong...). If you are in the middle of some particular computations with the use of programs AND you need to briefly stop, don't use [GTO][.][.]. You'll probably need to start over or find some mid point to continue. In most cases, switching the calculator to OFF and back to ON later to continue where you stop without the need to start over is enough and safe.

Sorry writing too much. I think that as a beginner, you must go for the most common cases and then getting deeper into particular ones. I hope I did not confuse you much.

Luiz (Brazil)

Edited: 31 Mar 2004, 12:01 a.m.


Thank you, Luiz,

I will implement some of your suggestions. I'm also printing out your posting for future reference.

Take care.




I meant to ask before. Are you an Formula One fan?



Hey, Wayne;

Thank you for asking. To be honest, I like the cars, the technology, the "apparatus", the beautiful women d8^D ... but I don't follow the races themselves. I don't even follow the scores... Sorry! Did it happen something about it for these days?

Some Brazilians used to like F1 when Sena was alive and running and no longer follow it after he left us. I am honest telling you I was never a race fan, but I like the technology... and the girls, of course.

I hope you're not disappointed... :^|


Luiz (Brazil)


No particular reason for asking other than that you are from Brazil. I have been told it is second only to World Cup Soccer (Futbol?) in popularity among Brazilians.

I follow it pretty closely every season and am continually amazed at the technology and the overal spectacle of it all. I have a Brazilian friend who stopped watching after Senna was killed. I think a lot of people in Brazil may have done the same.

I occasionally travel to a race, but have not been to the Brazilian GP yet.

Take care.



When it displays "STO OK: nn", the program should still be running, even though it's not displaying the goose. You can tell it's still running because the PRGM annunciator is still on. If you hit R/S, you're stopping the program. It should just run by itself for about the same length of time it took to get to the "STO OK" display, then display "RCL OK: nn" and stop.

I've only tested it on a 41CX, but it should work the same on a 41C or 41CV. If there are no other programs in memory, you should be able to execute "SIZE 044" on a 41C beforehand, and get a "STO OK: 44" display. Add 64 for each single memory module, or 256 for a quad.


Thanks, Eric. I assumed when the first results were displayed, and the "flying goose" went away, that the calculator was waiting for something (input from me?).

I had forgotten that the program is still running as long as the PRGM annuciator is on.

That will teach me to be a bit more patient.

Thanks again. You have been immensely helpful.

Take care.


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