I have read it is possible to connect an HP-41 to the PC. But I don´t really know how to do it.
Which module is neccesary?
Which PC port (or special card) is used?
Where is available the software?

Thanks in advance




the first module is the HPIL (82160A). It allows the HP41 to "talk" to the world. Then you'll need a PC board (I do not know its ID but for sure many in here know) for on-line operation. I have an HP9114B and I exchange information from the HP41 to the PC by using floppy disks. If I am not wrong, there is an issue about bus speed and compatibility, and you should use the standard HPIL-PC board in slow machines. Anyway there seems to be an updated hardware that to run in faster machines.

Sorry not helping that much. As I see your post for a few hours without answer, I decided to post this few information.

Best regards.

Luiz C. Vieira - Brazil


There are several relevant postings on the Articles section of this site. See #118, 260, 311, and especially #54. The easiest direct connection requires the 82160A HP-IL module in the 41, and the 82973A HP-IL PC card. The TRANSFILE41 software allows use in any PC with an ISA slot. Some other softwares prefer the card in a 286 PC.

You'll find some of the hardware expensive and hard to find.

Best of luck,


Dear Jo,

todays best solution for HP41-PC transfer is using the HP-IL/PC Interface card plus EMU41 software !

Refer to the HP-Museum article forum item 311 - there you get an imagination about the surprising and advanced features.

Needed software and hardware is easy available from Jean-Francouis Garnier (EMU41) and from me (HP-IL/PC Interface Card).

Best wishes from Germany - Christoph Klug


I've got a pair of nice portable 386 machiens with ISA slots- the part I'm missing is some sort of extended HPIL for the 41.

has anyone considered making new modules for that- or even perhaps recoding the stock HPIL module? (personally, if I had a rom I could pop into the existing HPIL, I'd be ecstatic)


Hi, Christof;

I have been thinking about this for a long time, and I think the easiest part is the electrical coupler/transformer. I have the original HP Journal issue about the HPIL and many electrical considerations are made in those articles, even a waveform analisys.

As many have already told here, today's microcontrolers are fast, low-powered and resourcefull enough to hold the task. I am almost sure it can be done. What worries me is the HP41 bus interface and SW translation/adapting.

Any clues? I remember many guys were working with this, but I have lost my e-mails and the some names come to my mind are: C. Klug (in this thread), M. Kuypers and V. Prevelakis, and I am sure there are others (please, forgive me).

Best regards.

Luiz C. Vieira - Brazil


Maybe there's a way to do it with just the existing HPIL modules? change the ROM inside? I don't have a spare to pull apart, but i can give it a try carefully and see.....


Hello, Christof;

unfortunately, HPIL chip is a single unit (at least for the HP41 module). I know HPIL ROM has already been downloaded, but we must consider that it runs in the HP41's CPU. The HPIL chip itself has a transparent protocol that can be replaced at the moment the new one accepts HP41's commands/signals and generates the same output/input handling. Internal registers are a matter of bus address.

Are you interested in having a look at the article? If you have the issue, try HP Journal, January 1983 issue. Its first four papers are all dedicated to HPIL design and specs at the literature level, neither hidden secrets nor protocol explanations.

If you do not have this issue, tell me and I'll scan the articles for you.

Best regards.

Luiz C. Vieira - Brazil



I don't have that issue after a scan of my shelf. I don't *think* it's scanned anywhere in my collection, either.

(and how I wish we had OCRd docco at least in part. to be able to search and custom make text files for travel.... ah, well)


I am still worlking hard on my MLDL2000, and there is some progress. I could not spend as much time as I wanted lately but I am now back on the track again. There will be an interface to the outside world, based on a very simple 3 or 4 wire synchronous protocol. This would support a parallel interface to a PC by bit banging the PC's parallel port. I am already investigating USB controllers which are almost single chip solutions between USB and a number of parallle bits, and that would give the MLDL2000 a nice USB interface. Please note that software has to be written as well, both on the PC and HP41 side.
The interface is primarily intended to be able to load and save the ROM and RAM in the MLDL2000.

As for the status of the MLDL2000: I am currently implementing the WROM instruction, but there is a nastly little bug in the state machine that I am trying to resolve. When that is done it is time to do the PC interface.

There are some questions that I would like to ask the forum:

- Is anyome familiar with the HP41 DATA line and how is works when a module supplies data?

- Is there more specific information available on the extra HEPAX instructions? I know what they do but wants some more specifics. It will be very difficult to implement though...

- Bank switching: Is there a complete overview of all the particulars?


Have you considered using the TI USB cable for (at least) the TI83+? It sells in the US for around $15 and TI has offered a $15 rebate for quite a while.

As I understand TI's explanation of their various cables, originally they used the serial port of the PC to connect to their calculators. But since the calculator interface was a simple clock and data system (not RS-232), they just used some of the modem control signals and bit-banged them. This required them to do something completely different for the Mac. Finally they made a USB cable with electronics to interface with the calculator's port.


Christof wrote:
> has anyone considered making new modules for that- or even perhaps recoding the stock HPIL module?

You don't need to recode the stock HP-IL module, you can write code to drive the HP-IL chip in the 82160A module without interfering with the ROM in the same module.

This is what the Extended I/O module does.

Just because the ROM is in the same packaging as the rest of the electronics, it doesn't mean that you cannot write your own code.

However, trying out your code is going to be "interesting" either way since both your new module and the replacement of the 82160A ROM have to be custom HP parts that can no longer be produced.

Sorry but you will have to use either an MLDL or an emulator.


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