Data Acquisition with HP-41CX


I have the following peripherals available to connect to my HP-41CX :

HP3241A Data Acq/Ctrl Unit
HPIL Module 82160A
HP Extended I/O Module 82183A

9114B Disc Drive
82164A HP-IL/RS-232C Interface
82169A HP-IL/HPIB Interface
IBM Thinkpad 365 (Windows 95)

How can I setup a data acquisition system, controlled by the 41CX to capture data at regular intervals. Data is acquired using HP-3241 via HI-IL, and store directly into a 3.5in disk that can be analysed later in Excel?

Can I also stream the data directly into my IBM notebook, using HP-82169?


Dear CapPs,

the I/O-Board manual contains a software application for HP41CX, which uses time alarms to run a data logger application.

Instead HP3241 I use I/O-Board or IL2000 system, because this includes some more features which are helpfully for data logging applications.

I/0-Board manual contains also a software + hardware modifucation for HP41, for waking up the complete system by an external event.

Alternatively to HP41 you can use EMU41 running on your PC -for controlling the HP3421. Unfortunately (as I know) the alarm functions of EMU41 are limited, therefore starting an data logger application by time alarms would not be possible for EMU41.

But EMU41 is really great for receiving the data from your HP41 and running some post processing routines. For example you are able to transfer NNN´s from HP41 to EMU41, take this feature for compressd data storing of your measurement data. Last not least the transfer of data from EMU41 to EXCEL is easy possible.

With best regards from Germany - Christoph Klug

"Using advanced interface technologies to connect your HP41 System to future " :-)


Hi Chris

Thanx for you quick response. I'm not entirely familiar with your IL2000 system. Could you please elaborate.

I'm using a HP3214 Data acquisition system because that's what I have on hand.

Incidentally I also have an HP95LX at my disposal too. Its got 512Mb of storage. Would indeed be neat to be able to connect to the system and use of it as data storage.


Dear CapPs,

for more details - which are helpfully for data logging applications please refer to HP-Museum article forum :

003 : HP41 hardware interface activities

192 : Interfacing IL2000 to analogue world

311 : HP41-PC gateway & emulator

For measurement data storing with HP41 system normally I use X-Memory (CCD module matrix files) or IL-Cass-Drive.

Regards - Christoph Klug


I believe you mean the HP3421, right? (not 3241) That was part of my entry into automated production test equipment nearly 20 years ago, along with the HP-41cx and other test equipment. (I went through the HPIL-to-HPIB converter though, so all the equipment was on HPIB.) See my "memories" article at .

As with any complex project, your approach needs to be modular. Learn the 41's alarm functions (especially control alarms), the file functions (both on mass storage and in extended memory), the HPIL and Extended I/O functions, and of course the commands for the 3421, and start piecing things together. Try various commands and watch them work, then write little pieces of code using the commands and watch those pieces work, then use the familiarity you've gained there as you begin writing the final application.

There was an HP-41 module to go with the 3421, but I understand it was really just to give it a "front panel" for someone who didn't want to look up any commands in the manual. I never had or used that module.


Dear Garth,

thanks for your interesting link - this was the first time I enter the memory section of HP-Museum :-)

Nice to see that some more HP41 enthusiasts using this amazing handheldcomputer also as an advanced system controller.

For the HP3421 exist the DAC-ROM - working as a "front pannel". The rom-images for this module are available at TOS. But for practical work the EXT-I/O does the same job.

Do you own a HP3421 including 8-bit digital I/O option ? Only this additional data lines make possible control functions.

If someone needs more I/O lines plus some different supply voltages - than I/O-Board or IL2000 would be an answer.

For the today work on workbench I prefer the HP3468 digital voltmeter, because this includes a practical user interface.

For anyone who likes the HP41 as a system including HP-IL -
and not only as a poor handheld calculator, EMU41 would be an interesting software application - because only EMU41 mirroring much of the system features of HP41 & HP-IL to virtual world....

Dear Garth, may be you want to give the readers of this forum some more details about your HP41 & HP3421 data logger applications, because I think most of the readers do not have an imagination about this funny possibilities...

Regards - Christoph Klug


> The rom-images for this module are available at TOS.

I'm sorry, but what's "TOS"?


Dear Thomas,

TOS = the other side, because of the laws of HP-Museum a direct reference is not possible.

Regards - Christoph Klug


TOS = the other side, because of the laws of HP-Museum a direct reference is not possible.

Forgive me for being stupid or whatever, but the laws of the HP Museum seem pretty common-sense to me. Are you saying that this "site that cannot be named" is an illegal one (free and illegal downloads of copyrighted software etc.)?

If that's the case then how about everyone not even talking about that site in the first place? Being cute and saying "TOS" instead of just giving out the URL is just hypocritical, if you ask me. C'mon folks, either stand up for what you believe in, or else just shut up already. Don't let's abuse this wonderful service that David Hicks is providing at

- Thomas


The museum software will not allow a post containing the URL for TOS to be posted. It will reject the posting.

This goes back (apparently) to a disagreement between the curator of the museum and the owner of TOS.

TOS hosts ROM images and other materials. The owner of TOS states that he has the proper permissions from HP to do so.

The curator of the museum disagrees (I think that's correct) and does not want the site mentioned here (hence the block if one tries to post the URL).

I've been hopeful the two can somehow work out this disagreement, because it is either OK or not.

The owner of TOS says he has the proper permissions. Seems like that should be easily verified.

Personally, I like both locations.

Usually, the URL for TOS is given by email reference, since it cannot be posted here.


Curiousity killed the cat, but I'll bite -- anybody care to fill me in on which site is TOS?

Replies to rebo84 at hotmail dot com



Since my latest HD crash I also lost all ROM images

DROP_ me a letter stating the URL



Hi (almost) all,

First, It's me who coined "TOS".

It stands for "The Other Site".

If you prefer "That Other Site", it's Ok for me too (I'm not gonna sue you for "Copyright" infringment...)

So, once I've admitted to be the one to blame...

...that leads me to the main question:

Mr Okken:

1st- Definition of what is legal or ilegal is a mere question of time and use.

2nd- You can call me "hypocritical", this won't made a different (worst) person of me, as it didn't made a different (better) person of you either.

3dr- Appart from your taste for judgement and moral advise:

most of us here are extremely careful when it comes to judge others. Most of us know that it is *really* difficult to tell wrong from right, and it's not a good idea judging without knowing *all* the evidences. It's not a good idea gudging from our living-room or from our keyboards.

You can, of course, have your own opinions, but please, we also have ours so, keep yours with you.

4th- Will you (any of us for that matter) keep on visiting this wonderfull site if you were aware that it contains links to child pornography sites?? Sure not!! But have you ever tried to check if *any* link referenced in *any* post could lead you to such a site, or even if one can place such a link in a post??? Sure not!! Do you consider it a worst behaviour to build a site where "free and illegal downloads of copyrighted software etc." can be found... or a child pornography one?? (Not answer needed)

5th- Copyright is a money matter. That's all about. And, to my mind, there are *really* few things that lead to inmoral behaviour as money does.

6th- Guttemberg would probably be sued by Cistersian monks (if they come back to live nowadays...)

7th- Knowledge is what makes the human being worth living, please, let it spread. The most brilliant brains in History fighted against the stablished powers trying to share their knowledge. Now he most weak brains ever figth beside the established power to keep knowledge restricted by law... Seems that we haven't learned much since Spanish Inquisition.

8th- If Newton, Einstein, Galileus, DaVinci, Heisenberg... would have kept the copyright of their knowledge and discoveries we simply won't be here.

9th- Mr. Furlow, (curator of TOS) is by no means banned in this forum:

AFAIK he has not been sued by HP, further more, you can also find a link to this MoHPC at TOS.

10th- Last but not least, you can find a link to TOS on this very site!!!

Of course it is not directly mentioned but it's quite easy to find. It is the case that Warren is the author of the best Windows base HP-41 emulator (freeware). So you can go to the "Calculator Simulations" link:

There you'll find "HP-41C Emulator (Windows)" at the bottom, and this link will lead you to Mr Furlow's site and... to "The Other (illegal?) Site"!!!

Will this change your mind, Mr. Okken, to think that David Hicks is also "Hypocritical" for that "cute" workaround??

Isn't it funny??

Fortunatelly, there are millions of people that can see a huge amount of greytones between black and white.

My best wishes to all of'em.

Diego Diaz, developer of Clonix and NoVRAM modules, none of which could have ever been conceived without the contribution of MoHPC people/info *and* TOS on-line (illegal?) documents.

Edited: 19 Feb 2005, 1:35 p.m.


From working a little with Warren Furlow, I have no doubt that he is completely legal in what he has done on his website. In fact, I think he's a little _too_ careful about some materials that no one would care about anymore. I personally have given him some materials for his website that after many months he still has not put up yet apparently because he has not been able to find whoever he believes he should get permission from. (Maybe a company has gone out of business or something-- I don't even remember anymore what it is that's waiting for permission to be put up on the web.) I'm on another forum and website whose owner has for many years just taken the approach that if he can't find anyone left to get permission from to post old materials, he just goes ahead and posts it with the idea that if anyone complaints, he'll either take it down or pay them a royalty-- their choice. So far he has not run into any trouble at all. The only company that did complain was one that forgot they already gave him permission. I know Warren has been trying to get permission to post a manual from one company that has no one left in it anymore who even remembers what an HP-41 is. They don't know about their product he wants to post the manual for, but they've asked him not to post any of their materials-- whatever they were-- they can't remember. Maybe if they could remember, they'd give him permission.


Hi Garth,

I just wanted to confirm your take on TOS. I too have donated several items and have found Warren to be completely above board when it comes to posting any copyrighted material. My experience has been much like yours in that Warren would not and did not post any of the material I donated until he had a full release in his hands. This was the case with the AECROM, the copyright to which I hold. I am also responsible for donating images and manuals for the NFCROM, Pcoder (ProtoCoder) ROM, ProtoPario ROM, and all associated documentation. Warren posted these as well but only after I obtained and forwarded to him a full release from the author and my good friend Nelson F. Crowle.

In short, it's difficult, no it's impossible, for me to believe or even imagine that Warren would post any illegal materials.

Just my two cents worth in hope that someday both these great sites can resolve their differences.

My Best to all,
Wilson (Bill) Holes


Just a short, unimportant addition:
I agree 100% with you, Wilson. I´m also confident, Warren (who is a good HP friend of mine) only pubishes maerial after getting the authorisation to do so.
As you know I do not publish much stuff at the moment (but that is another story). Anyhow Warren asked me for publishing my HP-41 module list, although it is downloadable on my homepage. You see, he does not only asks for commercial products, but also for hobby stuff like my list.

Warren, I realy hopy you find a conclusion with Dave.


A brief chronology as I know it.

Long ago there was a site with an interesting simulator. I linked to it. It became more popular and was occasionally linked to in this forum.

Sometime later HP told me that the site was hosting ROMs without permission and that I should prevent links to it in the forums. I complied. (I took a look at the site at that time and it said something like: These ROMs are NOMAS so I can place them here, which was surely well-intentioned but legally nonsense I believe.)

Sometime later the site owner told me that he had later received permission so it was OK now. That sounded great, but since it was HP who asked me not to link, I checked with my contacts. They hadn't heard anything about this. I tried more contacts. I tried several people in person. I even tried after beer. I asked other people who were and, still are, trying to get permission to copy ROMs for simulators. No one else I know has heard anything about it. Comments from two HP employees: (quotes from memory) "You would be wise to stay away from this" and "There are many sites with inappropriate HP content but I don't report them to legal for fear that they would take them all out, including the good ones."

Everyone points to Fred Valdez (the GM of the calculator division) as the person who can provide the definitive answer. I asked some time ago and didn't get an answer. I planned to corner him in person at HHC late last year but he had a last minute conflict. At HHC Eric Smith asked if there was any chance of getting some ROMs released for his simulator and Cyrille de Brebisson (Calculator R&D manager) said "I believe that will never happen". (Which tends to imply that he also thinks it never has.)

Later I emailed Fred again and this time I thought I was pretty clever: Instead of asking for confirmation that the site was now operating with HP's blessing, I only asked for permission to remove the link block and for HP to agree to hold me blameless for links to some site I don't control which are added by other people in this forum. That seemed like a simple request that didn't limit HP in any way. I even said I would reinstate the block on their request at any time. An assistant to Fred told me that they were looking into it and it would take some time. That's the last I've heard.

Perhaps the other site owner can ask his contacts to contact Fred. I have no idea whether Fred doesn't know, doesn't agree, or this just gets lost in the shuffle.


Dave, would if solve the conflict if the currator of TOS would publish his permission he got from HP or so? I´m shure, he still has them. Maybe he can also tell you, who gave him the permission and you could ask them back?



Guys, I am deeply gratified that you have said the kind things above!

As I said somewhere before, I could easily believe that one hand of HP does not know what the other is up to.

My initial request was made to Iain Morris who referred it to corporate attorney in Fort Collins. The attorney (who is an HP-41 fan as well) did some checking and eventually sent me a permission letter. It says:

"Dear Mr. Furlow:

In response to your request, Hewlett-Packard Company is pleased to grant permission for you to reproduce HP-41 calculator materials for your [TOS] archive website.

This permission is contingent on you including appropriate HP copyright notices along with reproduced materials. Further you agree to include the following in each copy you make: "

Then it spells out the disclaimer that I have pasted all over the place. That is it. There is no mention of ROMs and I never got an answer to that question. Nevertheless, I believe it is broad enough to include them.

As you probably know, I now distribute only .MOD format files. This format includes the ROM image but also the copyright notice and disclaimer and other information like how to automatically load it into emulators.

It occurs to me that HP may never settle this to our satisfaction.

Thanks & Best Wishes!



Thanks for the details. It seems more like people at HP not knowing what has been released in the past rather than inappropriate conduct in the user community. Just my 0.0153005 euros (at today's exchange rate).


Just a note: Sometimes they do not know yet what they release.

Take for example the manual for the '48gII' which is

for download on the HP-48G/G+/GX pages...

The manual has quite nothing to do with the HP-48,

like the 49g- has nothing to do with the HP-48G



Thank you all who have posted your position about this topic. I too highly respect both site caretakers, believing not only in their honesty and integrity, but also in their belief in their own positions. That is why I am happy to once again see this brought out into the open for further examination.

I personally believe that the core of the 'misunderstanding' lies with the current HP management not knowing about either their prior release or reasonable current position on the subject. After all, HP has no qualms about protecting their commercial/technical intellectual property in court - a simple cease and desist order would suffice - yet nothing has happened for years.

I am pleased that Dave is pursuing a resolution to this unnessary conflict within our community - perhaps a less strict approach would be wise until HP gets it's act together.

I support Warren's claim to release of the NOMAS as do most other HP41 supporters.



TOS = the other side...

Actually, I think it originally meant "That Other Site."



I'm sure this is the longest post I've ever made here.

The 3421 was rented by the company I was working for at the time. I don't own one myself. Yes, we also rented the plug-in output board which had, IIRC, ten relays or something like that, which I connected to some equipment we made in-house. Also on the HPIB were an HP signal generator and a programmable power supply. Other equipment involved that was not computer-controlled included amplifiers, a Bruel & Kjaer reference mic, and a small anechoic chamber. I know I'm forgetting something. Soon after that original set-up, we bought some other equipment and stopped renting. I do remember that we bought an HP3457A digital multimeter, a Wavetek signal generator, and a Cytek relay unit. Later we put in a PC with an HP Viper board (which is a 68K computer with HP BASIC on-board and HPIB built in), but the test speed was not much faster than it was with the HP-41, just because much of the computers' time was spent waiting for filters to settle and readings to come back from the equipment.

I had seen people in the engineering lab at my previous place of work (M/A Com P.H.I.) control network analyzers and other microwave equipment with their personal HP-41's, but the company didn't want to buy any 41's because it would be too easy for someone to steal them.

Since that first ATE setup, I've used a few other pieces of HPIB equipment with my HPIL-to-HPIB converter, including a digital oscilloscope from which I downloaded sets of 8K points for an FFT on the HP-71 and printed graphs of amplitude and phase versus frequency 15+ years ago.

Do not limit yourself to thinking that there are only a few pieces of equipment the HP-41 can interface to. With the interface converters to HPIB (and to a less extent, RS-232), there are probably thousands of models of equipment you can use. The HPIB fanout is 15 units IIRC, so you can have up to that many pieces of equipment in a rack connected to the HP-41 at the same time, in addition to the HPIL equipment you might have connected. HPIB and HPIL have so much in common that the interface converter is mostly transparent, and from a programming standpoint, equipment on the HPIB side appears to be connected directly on the interface loop.

In later automated test equipment setups, I used the STD industrial computer bus. (STD, by the way, came from "simple to design", not "standard".) Although this took longer to develop that "rack-and-stack" with HPIB equipment, it was more economical to do several identical setups this way because the hardware cost was much lower. The resulting units were also much more compact, suitable for shipping to our Korea and Mexico plants. Still, for quick set-ups that will only be used temporarily, it's very practical to use the HP-41 with HPIB equipment.



Dear John,

thanks a lot for your helpfully explanations about TOS.

Dear Garth,

thanks for your describtion of your data logger and measurement application. Because your setup included also a microphon and a B&K Preamp, you are testing acoustical equipment ?

Also your details about using the HP-IL/HP-IB converter sound interesting, today in our companie we using some HP-IB measurement equipment - controlled by PC and HT-Basic software.

In the actual HPCC Datafile Journal I published an short article about using the HP3468 Digital Multimeter with HP41 :-)

Best regards - Christoph Klug


> Because your setup included also a microphon and a B&K Preamp, you are testing acoustical equipment ? <end quote>

Yes. It was not just data logging, but producing various stimuli and checking the resulting responses of the product. There were also some DC tests on the product. The only Bruel & Kjaer component was the reference mic. Two other mics in the setup were calibrated against the reference mic. That was 15-20 years ago. Later automated test set-ups I mentioned performed up to 60 tests on each of several models of other non-acoustical audio electronic equipment (intercoms for private aircraft) with many inputs and outputs.

Again, some of the equipment is basically output-only; IOW, not for measurement. For example, the only thing to input from a signal generator might be status or error messages. Other than that, you tell it what kind of signal to produce, what frequency, what amplitude, and any sweep or burst instructions you want to give it.

The Cytek relay unit was only a bus listener. It had no way to put any information on the bus. All it would do is take instructions given to it and open or close relays.

The DMM probably did the most "conversation" in the sense that data was frequently going both directions. It took a lot of instructions to set its filters, inputs, modes, etc., and output status and measurement data.

You will generally send instructions to the equipment by forming strings in the HP-41's alpha register, selecting the HPIL address using SELECT (after doing MANIO if you're using the converter to HPIB), and outputting the string with OUTA. INSTAT read the status of an instrument. You will generally use IND to input data (numbers) from an instrument.

Edited: 17 Feb 2005, 3:42 p.m.

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