41cx to 41cx over HP/IL?


Is it possible for 2 HP41's to communicate over HP/IL? My goal is to transfer data between them using 2 HP/ILs connected together. The HP/IL manual does not mention 2 HP41s in a loop. I'm guessing that even if this works electrically, one of the 41s will have to look like a talker/listener, with the other the controller (default).

Has anyone ever tried this? Thanks,




in an HPIL system, the HP41 can only play as a talker controller, or simply talker. Other controlers, like the HP71 or the HP75, can be set as listener.

I have never heard about two HP41 connected in the same physical HPIL loop.



I'm surprised the HP41/HPIL designers never envisioned two 41's exchanging data. Ugly as it is, I'm sure the following would work:

HP41<->HP/IL<->RS/232<-Null Modem->RS/232<->HP/IL<->HP41




your arragment puts each 41 in a separate physical loop; it should work at the "electronic" level, but you still have a logical loop. It means that control messages sent from one talker will find the other talker. Would two talkers "live" with that?

I'm interested on this.

BTW, do you have the specs for the IL pulse transformer?

Thank you and success.

Luiz C. Vieira - Brazil


I'm assuming it will work since this configuration works for both input (INP) and output (OUTP) with a PC on the other end. I would execute INP on one 41 and OUTP on the other. Assuming the proper null modem cable, to each 41 the other end of the wire would look just like a PC (or any device). I can't test this since I only have one 82164 (RS-232C Interface).

What is an IL pulse transformer?




I answered to similar subject at: http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv009.cgi?read=25366




I guess as long as you don't need interactive communication, then either rs-232 to the PC or mag cards look like the way to go. Thanks!



No. The depicted configuration would mean that each
HP-41 is a talker, but they are both talking to
an RS-232 interface, which is the listener.
They are not talking to each other at the HP-IL level.
The fact that the RS-232 interfaces are talking to each
other don't affect HP-IL. And "talking" is perhaps a
small overstatement. RS-232 is more or less just
a case of exchanging data. There is not much of a
protocol at that level.


For adapting two HP41 together use two HP-IL/RS232 interfaces, or alternatively two HP82166A IL-Converter units. The belonging HP82166A manual describes this special application including needed wiring and software.

But much more interesting for the HP82166A IL-Converter are advanced hardware interfacing and measurement and control applications using the HP41 : „Control the world with HP-IL“ Two nice interface systems are absolutely powerfully hardware platforms for doing this : The battery powered, modular I/O-Board and the IL2000 system.....

The best today solution for interfacing two HP41 handheld computer systems together is using the new full version of EMU41 from Jean-Francois Garnier , plus PC with HP-IL/PC Interface Card :

First connect the first HP41 to this system and upload data, programs, any type of file or non normalised numbers = NNN´s. to virtual EMU41. Than connect the second handheld and download data, ,programs and so on to the second machine.

Emu41 gives you much more features : virtual display, printer (including barcode plot), mass storage, gateway to the DOS world, and an powerfully emulator including advanced plug in modules and ram-box features. More details about EMU41 you find in the HP-Museum article forum item 311 “HP41-PC gateway &emulator”.

Best wishes from Germany – Christoph Klug

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