HP-41 Hackers


Is there a forum for HP-41 hackers or serious users? If not, is there anyone interested in starting one?


HP-41 discussions are welcome here. If this forum gets swamped with 41 questions, we can move those into another one.


I would be interested in starting a topic. How about Synthetic programming? I would like to learn more about Curtain moving and see a real life example. I have not come accross an instance to do this but if it may help me I would love to know.


Jeff, do you have any synthetic programming books? Moving the curtain is not too difficult, (memory lost is a possibility if done incorrectly), and is most commonly used to renumber registers for subroutines. Using this form of programming, subroutines can be written without regard to preseserving th contents of any registers, since the main program will have moved the curtain up, protecting them from use. How much do you know about synthetic programming already.


Alot of the programs that I have written for work are synthetic. Curtain moving is one topic that I never have used. I guess i was just wanting to get a topic rolling.I do have quite a few books on synthetic programming.


I'd be interested in building hardware for the 41. Would like to start with an MLDL, EPROM box,... maybe with current technology (small uPs, FPGAs) ...

Anyone interested?

I posted a question here some weeks ago for the schematics for an MLDL, which came out in the PPC journal or CHHU some years ago. Does anybody have these. Please scan (high quality) the article and send with mail.




Reinhard, I have a bunch of the old PPC journals. Do you have any idea about what time the MLDL schematics came out? I might be interested in any MLDL hardware that you build.


Seems I meet the right people here (pls respond to my eMail-address, as for the moment I have no access to Internet and sit here at 2313 hours in an Internet-caffe). Like JF.Garnier, I did program an emulator of the nut-CPU, but it runs on an IBM-host (VM/ESA with fullsceen-CMS). I collect HP´s calculators and *ALL* accesoires (HS/SW). After the experience of collecting I sill go back to my HP41 as its 10 times more fun to program such a computer than cleaning old machines. Would be nice to here from youn if you started an separate HP41-hackers-forum. Bye.....Mike


I don't know that. I remember having seen such a thing, but I was not that interested then because I began my HP career with a HP-71B.

Any other people having an idea?

The circuit was rather large, I remember. No problem today, but a big problem compressing it into a small device at that time.


Ok guys, some info about Hp 41 H/W and MLDL below:

- HP 41 C Bus Interfacing by Jim De Arras

PPC Calculator Journal V7 N3 Page 20 ---> The basics.

- HP-41 Machine Language Development Lab - MLDL by Lynn A. Wlikins

PPC Calculator Journal V9 N3 Page 27 ---> All you want to know about MLDL, schematics at Pages 32 thru 34

- MLDL Ram Modification by Chris Rath

PPC Calculator Journal V9 N4 Page 25 ----> a helpful modif. to use more modern Ram chips.

- INSIDE THE HP 41 C by Kelly McClellan

PPC Journal V6 N6 Page 4 ----> Pages and pages of schematics, diagrams and photos about our precious thing and more !!!

also a chapter on how to make a plug for the 41 I/O ports (have to be precise in the making but I think contacts found on old 5"1/4 floppy connectors would do it right (golden plated models are best).

- Continued in PPC Journal V6 N7 Page 47

Want more ??? Do hurry to the URL below http://www.waterw.com/~jake-s/index.html and ask Jake Schwartz for his two CD-roms set of PPC Journal/CHHU Chronicle / HPX Exchange etc. Archive in PDF format. A modest fee for hours of reading, printing and wonder. Thanks Jake!

I would be happy to help any people wanting to make a MLDL, but I can't find the time do it myself for the moment. Feel free to e-mail me directly.

HP Forum is great!


Personally, I'd love to see more HP-41 stuff posted here (or anywhere). It's doubtful that I'd be able to contribute much (at least for now), as I'm still new to the HP-41 world myself. After many happy years with my HP-16C, I finally decided to get something with more powerful programming capabilities. It had to be RPN, of course, and it didn't take much research to settle on the HP-41 as the perfect choice. (Dan, your "HP-41 Memories" article here in the "Guest Contributions" area was a big help in making up my mind. Thanks!) Since getting a second-hand 41CV I've added a card reader, printer, and various modules, and have a bar code wand coming soon. I've just started getting into synthetic programming and would love to learn more about it (as well as other aspects of the 41). So please, I'm ready to listen to anything anyone has to tell about the HP-41.

(By the way: I recently bought my son, who's also an RPN addict, a 48GX for his high school math classes. It's a neat little machine, and I enjoyed playing with it, but I still prefer my 41CV. It just "feels right.")


Well, Wayne I don't often see the 41 and 48 mentioned in the same newsgroup, let alone the same post! Guess I'm really Reverse Polished, since I recently completed my BS as an adult, started on a TI85, went to a 48, then backtracked to the 41, to learn about now what I missed then.

Don't know why so much 48 bashing. It's a monster learning curve but if you're an insomniac or want to make "Your Calculatin' Life" (credit to Mr. Lianza) easier, the 48 goes way beyond the kid's toy so many think it is. Lots of dev and comm tools for the PC are a big help.

After just a few weeks with my 41 and a couple of super books, I see why the Cocoanut had/has such a loyal following. It's the machine that went to the moon, afterall.


I hope you don't think I was bashing the 48, because I wasn't. It's an impressive calculator, and my son's very happy with his. It's just that I like my 41 better. The programming is very similar to the kind used on my 16C (except much, much more flexible), plus there's the fun of synthetic programming (the main reason I selected a 41). Eventually, I'll start looking closer at the 48 too, but not till I've gotten a lot further along with the 41. (Besides, I got the 48 for my son, and he ought to get the first crack at mastering it.)

As for being Reverse Polished: I look like an idiot trying to use an algebraic calculator, because I've been thinking in RPN for so many years now. I get confused and start trying to use some weird hybrid of algebraic and RPN. (So 2 + 3 * 5 becomes 2 + 3 + 5 * ... darn, let me try that again... 2 + 35... wait, let me get my own calculator!)

(No, I don't really need a calculator to figure out that particular example. :-)


When someone says "Can I borrow your calc for a minute?", I just say "Sure, but it's a little different", then I hand 'em my 32sII, stand aside and watch the puzzled looks. When It never fails that when I ask the RPN clueless victim if he solved his problem, he always says "Yep, thanks!". Dust it off and back in the holster. Another "X" on my case.


Heh-heh, I've caught my boss like that several times. He picks up my 16C, pokes at it for a couple of seconds, then mumbles something about "backwards calculators" and goes back to his office for his Casio. I think he's getting wary of the 16C, but it's only a matter of time before he tries it with the 41CV...


I don't believe that the HP-41 went to the moon. The moon missions were from 1968 (Apollo 8 orbited the moon in 68) to 1973 (Apollo 17). The HP-41 was introduced in 1979. It rode on the space shuttle into earth orbit many times, though.


I still have a few hardware items leftover for doing speedups. I also used to combine up to 3 modules in a single port. I know about external interface to the timer module and I still have ONE HP diagnostic rom used by the HP repair department.

Andrew@AndrewSite.com 805-469-6714

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