HP-IL Sniffer


Hi all,
I just received a 41CX, a DEVILROM plus a EXT I/O rom. I have a 80160A adapter too (another one is possible).

Just wondering which are the "System requirements" to run a HP-IL sniffer on a second calculator.
Could I simply grab another 41C with some mem expansion or it is mandatory to use at least a CV.
I have seen somewhere that thare are 110+ registers as memory requirement, so at least I need a 41C with some memory.
Are there other ways to have a HP-IL sniffer that is not the usual pc card?

Thanks in advance,

Giuseppe Marullo



I think it would be easier to use an HP-71B as the sniffer,
since it's a bit difficult to have 2 HP-41's in the same loop.

However, since it's a loop, your sender gets back what it submits, so your sniffer could be your first HP-41;-)




thanks for your answer. It is not clear to me how to interact with the bus while at the same time use the calculator as a sniffer.
Would it be much simple (and cheaper) to have another one that is performing this task (if this is possible with a C/CV).

About the HP-71, maybe is cheaper to get a 75, that has a standard hpil port. I don't remember which is best at hpil stuff between the two.

Giuseppe Marullo


Hi Giuseppe,

for HP-IL functionality beyond the standard protocol maybe Christoph Klug and Jean-Francois Garnier are the persons who may have the answers;-)

AFAIK the HP-71 has the most advanced HP-IL implementation ever made.




I have already contacted Christoph, and ordered his manuals :)

Actually it seems that a HP-71 is rather expensive compared with a 75. Which could be a reasonable price for both?
The 71 does not have a HP-IL port/module, so you must add its price, while in the 75 it should be standard, am I right?

BTW, I have both devilrom and ext i/o rom, so it is natural to place both on different 41 and have one "sniff" the other' operations. They were not cheap by my standard, better use them.

Giuseppe Marullo


Yes you can use a second 41 as a sniffer but you need the
HP-IL Development ROM. This is because the ROM on the 41 IL module assumes that the 41 is a controller. In contrast the IL Dev ROM software is desinged for sniffing. You can get the Dev ROM manual from the MoHPC CDROM.

I have actually used this combination and its very powerful.

Having said that, the 71B is the best IL controller made so using this machine is probably a better idea.



Thanks Vassilis,
so you would purchase a 71 as a sniffer?
Anyone knows which is a right price for it, in good shape and with or without hp-il interface?


Dear HP-IL enthusiasts,

remember that it is also possible to use a PC with EMU41 or the new EMU71 plus HP-IL/PC interface card for monitoring the interface loop. Using the PC you get one or two virtual handhelds plus much more advanced features....

Best wishes from Germany - Christoph Klug


the problem is that the pc board is rather expensive, and you win another piece of history,---> the PC.
My current pc does not have a ISA slot, so I should equip my 41CX with a heavy peripheral!

I am searching for such a board anyway, but a USB porting of the board would be greatly appreciated.

Giuseppe Marullo


As Vassilis already sayed, an HP-41 (even an old 41C) with a "Devil"-ROM is sufficient as IL-sniffer. Just start MONITOR on it before you switch on an other controler in the loop. That's all. BTW, what are you going to do? Just currious <G>.



Hi Mike,
just wanted to learn from scratch a programmable calculator, just as I did *several* years ago, with a ti-59.

Anyway it started as a cool terminal to be used to setup a minisumo robot on the dojo. I don't want to use a laptop, there are a lot of people around and actually *nobody* knows the 41 around the people I know (within my same age).
Now, the more I dig, the more I would like to do.

At first, I will try to drive my robot using a HPIL->RS232 interface, then maybe a home made HPIL->GPIO or a HPIL->RS232, but the smallest possible.

Another interesting project would it be using a pic to emulate some rom, I have found an interesting kit that is able to read files from a FAT32 SD card, using a pic.

I don't have any software to preserve, so my point of view is VERY different from most, if not all of you. Maybe others would build something very different.

Who knows, I am still missing the CX "basic" manuals...go figure. there is no guarantee that I will go much further than 2 ENTER 2 + stuff.


2 ENTER 2 + stuff is "User Language", I suppose you go for MCode <G>


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