How many engineers etc. out there still using hp41?

Wondered how many professionals are still using the HP41 series?
Have met a few here and elsewhere, but... maybe there's more.
After all, tens of thousands got sold and they can't all be in the trash or behind a glass case.

Looking at developing some real add-ons for everyday professionals.
Also at doing reliable repairs as a service for fee
(a bit harder than it looks).

Anyone using their machine daily, what do you want in an add-on
and what would you pay for it?

Don W


At least two (you and me :)


Hi Geir. How are you going?



Still using one since 1989. Also using 15C and 32SII. Yes, i would pay for add-ons. In fact i also have a HP41CX Simulator on my workstation in case i forget to bring my calc.


Aerospace Engineer


I still use mine for light calculations and some simple on-the-fly programming.


Thanks for the F/B...

What sort of add-ons?



Thanks for the feedback. What do you do in your job, Namir?

What gadgets would you want and use?




I assist in design of spacecraft. Custom Overlays/module perhaps with triangle solutions, density calcs and Metric conversions without having to insert different modules or overlays. Similiar to TI 58C/59 program inserts. I know the new ALG/AOS HP Calcs have this. Also the older HP45, 55 and 31E series.

Thanks for your input.




If desired features are offered, then price will not be an object.



There are two other engineers in our small office of 12-people still using the 41. I am using a couple of 42's, but also have a couple of 41's. We are a civil engineering company, and mostly they are used over the top of drawings for figuring slopes, elevations, horizontal and vertical curves, etc. Many surveyors still have them and use them regularly, even though they may be using a 48 or some of the later data collectors for survey instrument data collection and transfer. If you want to see the level of use by surveyors of HP products (all obsolete) then go on eBay and search for "HP Survey*".

Although we do all of our drawings in CAD, and have a PC at every desk, it is just much easier to grab a calc, lay it on the drawing that is too big to fit beside the PC (or maybe a set of 200 sheets bound together), and do our calcs.

I have specialized programs for the 4 or 5 things I use most, but would use it for adding up lists, or anything where it is faster than creating a spreadsheet.

Most needed in our office would be a means to save and re-load programs and data. An ability to connect to a PC and transfer both directions for about $50 would be a huge help. Whether it is through an IR or USB or whatever. Since the 42 has no way of doing that, or even talking to another, that would be a huge help also.



Hi Andy,

That's prety fascinating. I remember reading about the AOS
module (program?) in HP keynotes in 1981 as youngster in the Air Force. (Was doing Comms Engineering before I dropped out due to stress).

If you can be even more specific and would be so kind as to dropp me a line at:

we can take this further and I can work out what I can do in what timeframe. I am just working from home but I don't see why I can't
put a bit of project management and QA into what I am doing...

I am trying to get to be *really good* at repairing these machines.
There are quite a few pitfalls, actually. But when you get all the way under the hood on the 41 machine design it's a really NICE work of Art. Shame about the memory size though, I always thought...

Thank you very much for your comments.



Hi Forrest.

Thank you for the feedback. It aligns perfectly with my initial
thoughts. I always wanted (larger capacity) data/program nonvolatile backup. And for all sorts of reasons 2-way IR
would be nice and has been planned by mytself from the outset.
I just wondered how many other people actually using "in-field"
thought the same way.

I am looking closely at doing two way IR with very good lighting immunity at (a slow) 1200 bps because that is what you can do with cheap modulated (light) carrier components.

I also want to do a nice permanent data backup/restore system which fits in a module.

If you want to discuss this further, please write to me at:

I agree totally on the space saving aspects of the calcs. They just "DO STUFF" as younger people are want-to-say today in a smaller package that nothing else does...
It was very cool to read your post.


P.S. In 1985 I used to fix desktop computers (a supercalculator with graphics and printer in-board) for Canon Australia in Brisbane. They were used a lot in roofing (truss design), and in a few med labs I think


Hi Don,

I do analysis of European stocks. I do a lot of regression analysis. I use Excel (make use of VBA macros to automate things as much as possible), MatLab, and MiniTab. I am also looking at other software like Mathematica, SPSS, R, and so on.

My hobbies are statistics (linear and nonlinear regression), optimization, root-seeking algorithms, and time series analysis. I use calculators and computer software to implement various methods and see how I can also use them for my work.

My use of calculators is very limited in my work. I have an HP-41CX near my laptops which I used to do simple calculations.



Use a 41CV every day since 1978. The same one. I've rebuilt the posts several times, all prior to using Internet. It replaced/retired my HP35.

Use many programs that I wrote myself, and many longer ones that I bought from Mr. Horne, during the 80's. (They were such a steal at $6.00 to $12.00 at the time.) I ordered a back-up 41CX the week they quit making them, I already had a back-up card reader.

Since I've found this web site I've repaired both card readers, several voyagers and pioneers. Thanks to eBay, I now have a three repaired 41CV back-ups too.

Really would like some sort of connection to a computer, so I could store/retrieve programs there.

Batteries are not as easy to find as they used to be. If the N-cells disappear, like the half N's we'll all be going to 357 powered devices, and a ratty 42s will go for $500 on eBay.


Still use my HP-41 CX. I have several and it is my favorite. I use spreadsheets, etc., but sometimes you just need a good calculator.


Hi Chas.

I am going to build something simple and fairly cheap that fits in a module. Probably will implement RS232C and maybe over an infra-red link (maybe two way).

What software would you want at the PC end. Would a standard app. like (MS windows)Hyperterminal be preferred? Would a dedicated piece of (program and data load and save)software be expected? What options would you want?


Edited: 14 Sept 2005, 12:05 a.m.


I still use my 41cx every day, although not very often anymore for the longer programs and data acquisition and equipment control. My home-made workbench computer and even the HP-71 is much better for that. I mostly use the 41 for quick calculations by hand, number-base conversions (with the Advantage module) for programming, various conversions and medium-short programs, my alarm clock, a Daytimer of sorts, and even keeping some phone numbers in. Most shifted keys are re-assigned.

I have the HPIL-to-RS232 and HPIL-to-HPIB (IEEE488) interface converters, but use them more with the HP-71 than with the 41. I also have the Mountain Computer HPIL 80-column video interface. I have sometimes wished I had bought a double extended-memory module for the 41 (which would fill my four ports with 6 modules since my HPIL and X-I/O are already combined to take only one port), but the need for the additional extended memory seems to be going away, as even without it now I haven't had to hook up either of my HPIL tape drives in years. The one thing I might still wish I had gotten when it was available was the HPIL-to-parallel interface-- the smaller, earlier, more versatile one. I can get the same function though in a round-about way, going through RS232 to my home-made workbench computer which has far more I/O of various types, timers, and other nice things than I could ever expect to find in an HPIL (or dedicated HP-41) device. Connecting the 41 to a parallel printer this way for example is a little more involved than I'd like, but I've done it when necessary (when my HPIL Thinkjet didn't work anymore).

I would be more likely to buy further accessories for the 41 if I could use them with the 71 as well, which basically means HPIL.

Someone else mentioned difficulty in getting N cells. They're always available at Radio Shack, Sav-On, Home Depot, and all kinds of places, especially drug stores and consumer electronics stores.

Edited: 15 Sept 2005, 3:40 p.m.


Hi Don

I used my 41C on daily basis until I had a severe battery leakage after vacances in 1998.

After that I converted to a 32SII for on-the-fly calculations and short programs.

In 2004 I found a beautyful 41CV. So, after 6 years, I had again an 41.

Today I use it for larger programming tasks, always with printing routines for the IR printer. To make the story short: My daily favorite is the 32SII (smaller), but as soon it goes into programming or repetitive tasks, it comes the time for the 41CV.

My job: IT consulting and project management for solutions in enterprise content management sector.

If I could wish I would like some media card (SD, MMC...) external memory storage. Maybe as slot solution, or incorporated into a card reader device hull.


Hi Don,

I would love a simple way to hook my CX to my Linux laptop.

-> Geir :)

PS: I'll ship the module as soon as I can get my head above the waterline and get to the post office.


Hi Don,

for 25 years I have been using my 41s almost daily. I got my first one when I was a kid and used it throughout high school and university. Nowadays it is the 17BII that tends to be most used, though, but that's because the financial functions of the 17BII fits better with my current job as consultant/project manager than the standard scientific functions of the 41.

I have always liked the "look and feel" and functionality/programmability of the 41 series. For me there are only three shortcomings 25 years after 41 series was introduced: speed, storage, and communication. I'll pay for products that will improve on the 41s in either of these areas.

Good luck with your project(s)!




Hi Geir! How are you doin'?!

re: module, No problems!

re: Linux link, I'm working on a general purpose rs232 link.
may even be two way IR at 1200 baud.



Hi Arne!

Thanks for the feedback! (and encouragement)
I am starting on actual hardware / firmware at this time, finally!
I will certainly keep you posted on the IR and storage projects.
You may want to look at my website again.? Early days...

I was 17 when I bought my 41CV (serial number 2103A...)
so that makes me 42 ;-) The answer to Life, the Universe and Everything, so they say.

The 17 is very nice but I don't know much about finance and have never used one but yeah, balloon payments and amortization, etc...
I can dig it. Anything numeric with a dollar sign in front of it
makes me nervous, I don't really know why...!

Don W


Hi, Don;

I am almost sure I’ll start some discussion, maybe some flames, but I think that as you ask for some feedback, let’s try a few thoughts.

When I bought my HP41C in the 80’s I used to dream of possibilities and add-ons. I was later known about the 41´s adaptation of the HPIL system, but I could not afford any of those. I remember showing a friend of mine the HP41 running programs I wrote for 3D and complex arithmetic, and at his turn, he showed me his Apple computer. Even if I could work with a color screen and use the whole bunch of kilobytes plus floppy disks, I’d still prefer my pocket-size, fully portable HP41.

Now I use the HP41’s I have from time to time, mainly to run earlier programs prior to store them or to port them to other systems. Most of the programs I wrote for the HP41 are now available as internal functions, routines in newer models, but some of these HP41 programs contain specific procedures or data handling that may be useful somehow. I still use RPN/RPL calculators at the academic level (I’m an electrical engineer and since 1995 I act as a university teacher), but when I find the time and the ‘tease’, I go for some RPN exercise. A couple of days ago I wrote a small program for a friend that asked me if there was a way to compute NFV (net future value) in an HP12C/Platinum without the need of changing existing TVM data neither use extra storage registers. My final version is a 31-step, fully automated program.

If the HP41 system is still active, in production, or (even better) has compatible, updated replacement components, then I’d go for new add-ons. In fact, I think that the only ones are worth buying today are Meindert Kuiper´s MLDL, Christoph Klug´s HPIL/PC connection card and Diego Diaz´ Clonix. As for what I know, with these add-ons, you can make the HP41 sing and dance.

I myself like to keep track with the new, and I have been dealing with some experiments involving bidirectional IR I/O for the HP48/49 series. Just a few tests with sending and receiving, nothing exceptional so far.

Thanks for your offer, Don. I hope you take these words of mine as my own feedback. And guys, please, don’t toast me up…


Luiz (Brazil)


Thanks Don. I too was in USAF '64-'68 in Montana at "Malfunction Junction" (Malmstrom) during Minuteman missile build-up years.

Thanks for e-mail address. Will definetly write and express desired add-ons for HP41

Warmest Regards


Nowadays it is the 17BII that tends to be most used, though, but that's because the financial functions of the 17BII fits better with my...

If you can find yourself an Advantage module for the 41, that'll give you the TVM (time value of money) program for the financial stuff.

Hi Don.

Tried to lurk only, but had to add my .02Cdn (.0000001 USD). I am a petroleum using mine daily. Not so much technical anymore, but still a daily driver.

1) Two way transfer with the PC. NOT using Hyperterminal, rather a standardized program such as kermit or vt100. $150 w/ cable? USB 1.0/serial/parallel.

2) Extension of the 41 screen/stack through the PC, i.e, trace on the printer. This would also allow editting of programs in your favourite editor. Perhaps printing as well. Why? It would be record of work done, and later could be a replay of your session.

3) An interface into a memory card. 8/16 MB would suffice, but it would be better if I could then put the memory card in to my PDA. Perhaps through the card reader.

4) Replacement battery/module traces! How many 41's have been put into drawers because leaking batteries ate through the traces? I would pay up to 25 USD for a new one. This should be a simple thing to do.

I know that there are some applications out there that do exactly what I am seeking, but I am seeking something simpler. I find it easier to use my PC keyboard, but I prefer using the 41. If I could write a program on my PC, then xfer it to my 41, I would be one happy duck.


Thanks for your reply Don,

2-way via infared economically would be great. I'd have to go buy an infared mod, but I'd do it if the economics was willing.

Whatever is the least painless with Windows. I haven't tried hyperterminal since Win3.1. For the amount of information going back and forth it should not be a problem, but likely more universal methods exist.


Thank you, all, for your GREAT FEEDBACK...

Will be implementing the best and most popular ideas in the next three to six month time period. Yu can stay posted by visiting
my website.


Don W



Another civil engineer here, class of 1980.

There is one engineer in my office who still uses a 41CV, and one who did until he lost his a year ago. He bought a 48GX, doesn't like it, but got promoted to VP, so it's a moot point. I know of several other engineers in other offices who still use one version or another of the 41. I have a 41CX that I use sometimes, but I mostly use my 42S and once in a while my 48G+. For a 41, I am more likely to use Warren Furlows 41CX emulator. I typically use it to run some older programs that I haven't spruced up yet to use the 42S menus, or simply won't fit into the remaining memory of the 42S.

Since I'm the only one in the office who ever took an interest in writing programs, the guy who still uses the 41CV uses several of my programs.




I was thinking of building my own IR module... if you get my drift.

Stay in touch because I will definitely be doing something along this line.



Hi Andy,

I should be able to engineer and produce either single or short run
manufacture of application packs which will comply with your requirements. The time frame to supply finished product is in the next four to six months including software writing time.

Do you need MCODE in the application packs? Because I'm going to have to network with people or do some reading and creative fast-tracking to do that. I still am quite certain I can do it though.
I've looked at coconut (cpu) asm code and it's not too hard;
the architecture is nice.

The triangle solution stuff you speak of, is that out if the MATH I pack?
Any further info you can provide to me by writing me at:

Just mark it in confidence and encrypt it and bind me with a non
-dsiclosure contract if it is sensitive.

Yours faithfully,

Don W

Edited: 15 Sept 2005, 12:25 a.m.


Hi Luiz,

Really good to hear from you about your work and your interests in maths. Plus the HP gear you have and use.

I am actually an EE dropout (long story) turned small system tech
and defacto EE (contractor). Also into NT4 systems admin and also tinker with LINUX / UNIX when I feel I need to. I have an educated laymans interest in maths. But I failed D.E.s at UNI...(subject called ME201 [maths for 2nd year engineers -
differential equations])

Back to the 41: There really is nothing like these old machines.
So far as I know the 41 is rather dead in any form of manufacture.
I am interested in preserving and repairing the hardware, plus
assisting with eliminating the weakness of no cheap connectivity and poor memory / storage, etc.

Modifications and enhancements are for me only a way to increased utility, not really for hacking mcode (though that is fascinating to many people here, including me to an extent).


Hi Jim.

Thank you for your comments. Very interesting.
I don't like Hyperterminal. I was thinking of a one protocol like kermit or something similar. I always used to use PROCOMM (now here's a blast from the Past...) in the MS DOS days.
Was thinking in the price range you mentioned. Serial though,
as it has more utility for machine control than USB.

Straight serial would mean a linux/unix link also.

SD memory cards have been mentioned to me before. Has got me seriously thinking. Would one want that amount of ram? Would be very good for storing data sets.... That amount of storage does mean an intelligent peripheral to maintain an indexed library
of data for the 41 to access, so i thought people would rather
have a laptop do that...?

Tracethrough, well thats a really neat idea, but if you can tell me a bit more about how you want it to work and I might be able to actually build it for you. Anyone else want something like this? If there is enough demand then a good idea can get engineered into reality. Meinderts mldl2000 is a good example of that.

Battery flexstrips. Simple? yes. Cheap? No... I can't see it.
Copper on mylar (or whatever it is) can't be cheap in low run quantities because it's low demand/specialized. I am looking at ways to fix this interconnect problem but can't get past hand repair of machines sent to me as yet. Still thinking about it though. I would love to see everybody able get their old 41 machines up and running again. Most units I have seen sold on Ebay have these problems.

I am also looking at a really neat way to repair the stress cracking of the plastic shell mouldings that all old machines suffer from in time. This is a serious "killer" of machines.

Anyway, thanks for the really interesting feedback, Jim.
I'll give the solution to those problems you raised serious thought.


Edited: 15 Sept 2005, 1:01 a.m.



I am in a similar situation but am probably much older than you. Maybe because I had some programming experience back in the mid 60's (when I was in the Army) the 41 seems really easy for me to program and when it first came out I wrote a COGO program for it that remembered coordinate points by point number. The survey module makes you type in the coordinates every time and that becomes a bummer real quick. I had a program that would traverse, inverse, and do the BB, DD, and BD intersections allowing you to set and recal points by number. As I recal, besides the program you could hold about 60 points in memory. It was two dimensional so we wern't carrying elevations with the numbers, just the northing and easting. That quickly got converted first to tape storage with a little more room for the program features, then to the disk drive. We had about four survey crews using it. (I wish I had kept a copy, but it looked like the laptop and pc were the future).

I really like the 42. It is light and fast and has that extra line on the screen, etc. I hate that it can't be backed up. You are right. It also needs more memory. I also really like the 71. Its survey module remembered points by point number and did some really slick stuff for that time.

My job is solving peoples problems. Most of them deal with grading in one way or another. Some with property boundary descriptions. Most of them are real problems that are happening now, and someone is really interested in getting them fixed quickly. The current thought process is that if they can fax or e-mail me a problem then I should be able to answer the question in the same time period that it took them to ask the question or pose the problem. Because of the type and variety of problems I deal with, the pc is seldom involved in the solution. It is more a process of fresh ideas from a different viewpoint and the 42S provides the necessary calc support. Once the solution is determined then maybe time spent on the pc in Land Development Desktop or maybe hydrology and hydraulic calcs.



SD memory cards have been mentioned to me before. Has got me seriously thinking.

I'd recommend MMC instead. MMC uses the same form factor and even the same connector; but you don't have to pay thousands of dollars to the association, plus royalties, to be able to make and sell MMC-compatible equipment like you do with SD. One of the industry magazines predicted that MMC will be gaining more market share against SD because of this. MMC does have an SPI mode too, which makes it really simple to interface.

Hi Garth!

Thanks for the advice (I haven't bothered to check this stuff out
in that legal/costs area). For sure MMC would be the deal...
and SPI is what I am looking for, because that will dove tail with the IIC buss which I will probably implement the comms to work on.

I am looking at something a little lower power than what Diego has done. With similar general capacities... or better, using a different approach. I wish to get close to truly emulating the old modules themselves, if possible.


Edited: 15 Sept 2005, 3:53 a.m.


Hi Garth. I will make myself one... ;-)



Hi Andy. Way cool...

I don't know whether I should tell you this, but I
like Stanley Kubrick movies (finally saw Clockwork Orange the other day for teh first time!), particularly 2001 AND:

Dr Strangelove (or How I Learned to Stop Worrying and Love the Bomb)

(Scary when Art imitates Life.)

I also liked Failsafe.



The MLDL2000 is designed just to be able to do all this. Of course it requires a special program on the PC, but my plan is to ultimately have the PC emulate mass storage, printer and maybe keyboard and display as well (althoug it is then better to use V41 or another emulator). There is no need to modify the hardware for this, all should be possible to do this in the PC software, a special ROM and perhaps some modifications in the CPLD 'firmware'. Communication is through USB, even the upgrading of the CPLD firmware. Note that these features are NOT implemented yet, but will be my next project for the winter evenings. Since the design is completely open, you are all invited to do your own stuff!

Another possibility is to use the HP41 as the input device for V41 with the right modifications to V41 itself.

The MLDL2000 has a ridiculous large amount of storage (that is compared to the HP41 memory itself) and a memory card is not really needed. ROM images can easily be backed up to the PC.

The only think that the user community should do is to make software for the host computer supporting Linux, since I only support Windows myself. Again, with the open design of the MLDL2000 this should not be too difficult.



Hi Don.

1) Straight serial would be great! Serial link and standardized protocol would allow MAC/Linux and PC's to talk to the 41.

2) The SD card would allow transfer of programs from PC to 41 to pocketpc/palm. I want to save my 41 for better things, however I also would like to run prgrams on a pocket pc emulator when I am out in the dirt and don't always have access to my laptop. Pie in the sky stuff, but it seems that the people here can do anything with the 41 (unlike myself who only can dream of programming in mcode).

3) The tracethrough idea is one that I haven't fleshed out yet. Initially, the PC was simply to be a virtual printer for the 41 - ergo any printing could then be reflected on the virtual printer and then a txt save. Ultimately, I was dreaming that if a 41 active playback were used, it would be a simple matter to then create a checksum for programs after a certain number of steps. Thus, program data entry error could be reduced, as well as a transaction record of the session. A playback would not be required, but again I am doing a little dreaming...I am also trying to stimulate a little conversation on something that I think might have some merit.

4) I am very sorry to hear about the flex strips. I guess I should have thought a little bit about the fact that there is a reason no one has done this. Every second week I get a spam email from a chinese vendor offering to do printed circuits and copper traces. I will pay more attention in the future and maybe I can get them to put something together. I see this as the biggest single shortfall of the 41.

I wish you the best of luck in your endeavour to return the 41 to its rightful place at the head of the class. It is a noble venture, and you have some great persons available for resources.


Yes Don, i remember Clockwork Orange, Fail Safe with Henry Fonda and the remake a few years back with Don cheadle. Also read the book. They used film of the B58 Hustlers (Vindicators) taking off. I remember the thunder they made when they took off from Kelly AFB in Texas with full afterburners on while i was in Basic at Lackland. It was the most overwhelming jet noise i have ever heard. I also have Stanley's Nightmarish epic with Slim Pickens riding an H-BOMB. There was a movie (UK) called THREADS made in '80s showing the aftermath of nuclear hallocaust. Had F4S taking off from from UK bases. Phantoms were part of NATO in COLD WAR years and used as primary Nuclear weopons delivery platforms. I also remember the Cuban Missile crises. Almost stopped doing my AlgebraII homework. Figuered world was going to end. Opps, just gave away my age. (59)

Warmest regards,




MCODE not required. Yes the triangle solutions are out of the Math pac. Summations of moments of enertia would be nice. More detailed data request will be sent via e-mail



I return to my Pro/ENGINEER WILDFIRE CAD modeling HP xwd100 workstation


I also would like to run prgrams on a pocket pc emulator when I am out in the dirt

I use eV41 on my iPAQ 6315 (download here)

Give it a try if you already haven't: quite good in my opinion.



The R/S key on the 41C I bought in 79 has become unreliable but I bought a goverment surplus 41CV about 9 years ago and it is daily use. Mainly for temperature and unit conversion programs that are assigned to labeled buttons.

I have not tried a 42, 15 or any other HP calculator but have never come across anything as versatile, functional and as convenient as the 41. I have card reader and wand but not used either in the last 5 years, but I just tested the card reader and it works fine even though its never been opened up.

Wish list...

data transfer with pc that does not cost an arm and a leg!

Ian Phillips, Cheshire UK


Hi Meindert.

Whats the power drain of the MLDL2000?
How rugged and reliable is the system?
What does a complete pre-tested unit cost?
Has there ever been any mldl or 41CX host crash?
How often?
What is the MTBF?



Hi Jim.

I am thinking that maybe I am able to just fix the flexstrips if people just send me the BACKSHELL of their machine. That would get the weight down and maybe the cost and would be (only a little) less disastrous if the post goes awry.

The thing is that in a moderate leakage, corrosion or contamination occurs on the gold flashing on the keyboard PCB, so the machines require my attention to repair this. I also permanently fix the problems of failed ports and intermittent crashes caused by corrosion on the interconnect, without soldering wires into the machine (!). So the repairs are solid and restore the machines to original (you can remove the backshell).

I am looking at the best way to reinforce the screw holes which crack over time (this is a very weak design area). Given thats resolved I think these machines could last another ten years, maybe twenty? Does anyone know the life of a well made LCD display?

An Italian friend of mine remarked that it almost unheard of for a calculator (or any small computing product) to last 25 years and he wondered what their lifespan really is... We will see.

As regards the people I have here to help me, yeah you are right they are a great bunch.


P.S. I HIGHLY RECOMMEND Warren Furlows V41. It is very, very nice.

Edited: 15 Sept 2005, 5:31 p.m.


> Does anyone know the life of a well made LCD?

I'm not aware of any limits on the life of an LCD as long as it's not abused. I have seen one that turned dark from being in extreme heat for a long time, and I've read that the worst combination is heat and moisture. The LCDs on my own HP's that are getting close to 20 years old still have bright, silvery backgrounds and really black segments or dots. Ditto for my workbench computer's LCD which is also nearing 20 years of age. I have several other LCD samples from products I've developed, and these are also at least 15 years old and appear and work as new. I have purposely tested LCDs at temperature extremes, but did not leave them at those extremes for more than an hour or so. At super low temperatures, it may even take seconds for a segment or dot to turn off or on before it gets so cold it won't work at all (like -40ºC). At high temperatures, the display may even turn negative-- ie, lighter dots against a dark background and be hard to read. But in all cases, everything went back to normal when the LCD was brought back to a normal operating temperature.


Hi Don,

A lot of questions, most are answered at my website. It is as rugged as you want it, since the unit is shipped as a kit with an empty cardreader shell, and you are the one to assemble it. I do offer an assembly service, and I think it is just as rugged as a normal cardreader. Just do not abouse it (I would never do that with my '41 anyway).
Current consumption is about 8 mA extra when the HP41 is running, and virtually none when in standby or off. Current may be a bit higher if a gold cap is installed for battery backup and it needs to be charged by the HP41.
And yes, I have seen some crashes in the HP41, but these are mainly due to bad contacts or bad settings. Some I have not been able to fully explain yet.



Hi Andy.

I am posting to advise that my programming jig for the
ROM emulator (Diego Diaz's Clonix clone) is running and I am in a position to roll your custom application packs (and write fully tested code for you).

I can also do some limited characterization if required:

Temperature limits testing from -20 degrees Celsius to + 45 deg.C
Undervoltage latch up / 41 system crash testing and limited impact testing (2 meters to concrete). I can't characterize for RH but can quote an RH figure at which the tests are run.

Modules will be available hermetically sealed in standard module housing and can be reprogrammed using a jig. All modules would be 100% functionally tested and low voltage tested (for latch-up etc.)
prior to dispatch.


Don W

Edited: 18 Sept 2005, 10:45 p.m.

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