hpil hpil

HP-IL Resource Page


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I present here some personal material for the HP-IL:

- The PIL-Box, a HP-IL / USB interface. The free ILPer software emulates a basic display/printer and a mass storage unit on PC using the PIL-Box. Main usage is to load/save programs from/to PC.

- The PIL-IO board is a real, self-contained HP-IL device combining a mini HP-IL/GPIO interface and a simple HP-IL/serial link, to experiment with HP-IL at low risk and minimum cost. Main usage is to interface the HP-IL loop with electronic circuitry, such as an Arduino board.

The PIL-Box, a HP-IL <-> PC link solution

The PIL-Box is a HP-IL/USB translator. It uses NO OBSOLETE HP PARTS such as the HP-IL chip or the custom HP-IL pulse transformer. It aims to be an alternative to the old ISA HP-IL board (HP82973A) and to be compatible with most computers/OS that support USB.

July 2009: First units delivered to users!

September 2009: New batch of PIL-Box, using a mini-USB connector and a slimmer housing.
The PIL-Box firmware has been improved with new functionalities:
- 115 kbps serial speed support (useful only with the HP-71B, no noticeable speed improvement with the HP-41C),
- the PIL-Box can now be the loop controller,
- several bug fixes, mainly when used with the HP-71B, which is a powerful HP-IL controller but quite strict regarding HP-IL protocol compliance.

October 2009: Firmware update 1.4
This firmware update corrects a timing problem when using the PIL-Box with a HP71B and HP-IL module version 1A. If you are in this case, contact me for an upgrade. The fix is not need if you are using a HP41 or HP75 as loop controller, or if you have a HP71B with HP-IL module 1B.

February 2010: New ILPer software
The new ILPer version no more requires the installation of the MS NET Framework and is more robust, thanks to Christoph Giesselink.

December 2013: The PIL-Box is still available!
I’m still able to provide the PIL-Box or the PIL-IO board, either fully assembled/tested or as a component kit.

May 2014: Firmware update 1.5
This firmware update provides improved transfer speed. The gain vs version 1.4 depends on the host system, an average value is about +25%. Furthermore, there is no need to tune the FTDI driver parameters anymore.
Contact me if you have a PIL-Box with serial number less than P159 and are interested to update the firmware.
Note: This update is interesting for people using the HP-71B to load large files (for instance ROM image with ROMCOPY). There is no gain with the HP-41C since this machine is really very slow…

November 2015: Firmware update 1.6
This firmware update provides a better support for managing HP-IL Service Request. This will be needed for future virtual HP-IL devices such as a remote HP-IL keyboard or a close emulation of the HP82162 HP-IL printer. Contact me if you need this update.

February 2016: PIL-Box and PIL-IO firmware versions 2.0
The PIL-Box and PIL-IO are now using a new microcontroller and the firmware has been updated accordingly. There is no functional change, the PIL-Box and PIL-IO firmware versions 2.0 have the same functionalities than the PIL-Box firmware 1.6 and PIL-IO firmware 1.2 respectively.

April 2016: PIL-Box firmware update 2.1
This firmware update for the PIL-Box provides a support for a faster communication speed at 230 kbps, for use with ILPer 2.2 or higher. The 9600 baud speed is no more supported by the PIL-Box.
Users of PIL-Box with firmware 1.x can upgrade to 2.1 by changing the microcontroller, no modification of the board is needed.
The performance gain at 230 kbps vs firmware 1.5 is about 40% using the HP-71B. There is no gain with the HP-41C since this machine is really very slow.

February 2019: The PIL-Box is still available!
There is no firmware update planned but I still support the PIL-Box and PIL-IO board. Contact me for details.

March 2020: PIL-Box availability on hold
The PIL-Box will be unavailable for an undefined period of time. Resources have been updated in the support documents for DIY projects.

June 2020: The PIL-Box is available again!

November 2020: PIL-Box availability on hold
The PIL-Box is unavailable again due to the second lockdown in Europe. Hope to resume soon...

June 2021: The PIL-Box is available again!
In the future, assembled units may be available in limited quantity and with longer delays, so if the PIL-Box/PIL-IO component kits are suitable for you, it will be faster to get them.

November 2023: The PIL-Box is available, now with 3D printed panels!
The PIL-Box is available again, in small quantity batches (i.e. somehow longer delay).
Now, the front/back panels (USB/HP-IL sides) are 3D printed, avoiding the burden of making the openings.
See here for a detailed description: 3D printed panels for the PIL-Box.

The USB PIL-Box board                                


The PIL-Box parts                         The board installed inside the housing,
with HP-IL cables attached

Important: the HP-IL cable shown on the pictures above is NOT provided with the PIL-Box and must be added by the user.

I can provide either the fully assembled/tested PIL-Box, or a kit to be assembled (basic soldering skill needed).

PIL-Box Setup Notes : Connection of the HP-IL cables to the PIL-Box (pdf file – Sept 2009)

PIL-Box Kit : Description of the component kit to be assembled (pdf file, for use with firmware 2 - Feb. 2016)

The PIL-Box is designed to work with the ILPer software.

For more information, contact me.

The PIL-IO board

The PIL-IO board shares almost the same hardware than the PIL-Box but has a different usage with a dedicated firmware.

The PIL-IO board provides 4 digital input/output lines and a serial link (UART type, logic level) to the HP-IL loop. It can be driven by any HP-IL controller such as the HP-41C or the HP-71B.


The PIL-IO board is intended to be used by electronic hobbyists and aims to be a substitute to the old HP82166A converter to interface the HP-IL loop to electronic circuitry.

Note that there is no USB port nor housing, and that an external 5V power supply is needed (3 x AAA batteries work as well).

I propose the PIL-IO as a component kit, upon request I can provide it fully assembled/tested. Contact me for more information.

PIL-IO presentation General presentation and demonstration at the Allschwil meeting (Nov. 2014),
  including an example of connection with an Arduino board. The Arduino sketch used during the demo is here.

PIL-IO board documentation Description of the PIL-IO board and instructions for use (pdf file – Feb. 2016)


> Is a component kit available?
I propose a component kit with the PCB, the programmed PIC uC and all the passive components, and with a bare housing (raw panels to be punched), see documentation above. Contact me if interested.

> Will the PIC source program be released?
I’m providing the source program of the PIL-Box version 1.4 which has used for several PIL-Box batches between 2009 and 2013, it works well with the HP-41C and HP-71B (and other HP-IL machines as well), but doesn’t have some features of later versions such as enhanced transfer speed (1.5 and later), advanced service request management (1.6 and later) and fast 230 kbps communication speed (2.1 and later).

> What software will support the PIL-Box?
The ILPer software (source files included) is freely available, my wish is that ILPer will be the basis for people to develop applications to support the HP-IL.

> Is a special driver needed?
The USB PIL-Box uses a FTDI chip. The drivers are available at FTDI Web site, they are free, well supported and available for most Operating Systems.

> Is an external power supply needed?
No, there is no need of external supply for the USB version. The PIL-Box is powered from the USB cable.

> How is the PIL-Box connected to the HP-41C/HP-71B/HP-75C?
The HP82160 HP-IL module is needed for the HP-41C. For the HP-71B, the HP82401 HP-IL module is needed as well. For the HP-75C/D, the HP-IL is built in the machine. One single HP-IL cable (not provided with the PIL-Box) is also needed to make the connection to the PIL-Box; this is done by cutting the HP-IL cable into two halves and attaching it to the PIL-Box screw connectors as indicated on the pictures above. No soldering is needed.

> Can the PIL-Box be connected to the HP-41C (or to the HP-71B) without the HP-IL module?
The answer is no.

> Can the PIL-Box be used to access a USB key or other USB devices from a HP-41C or HP-71B?
No, the PIL-Box has no host capability. It can only be used as a USB device communicating with a host (usually a PC).

> Can the PIL-Box be used to access HP-IL from a HP50G for instance?
The PIL-Box has no host capability. It can only be used as a USB device communicating with a host (usually a PC).

> What is the difference between the PIL-Box and the PIL-IO?
The PIL-Box and PIL-IO share almost the same hardware with different firmware and usage:
The PIL-Box is a HP-IL / USB interface that is used to connect the HP-IL loop to a PC. Main usage is to load/save programs from/to PC.
The PIL-IO board is a real HP-IL device providing digital I/Os and serial link to the HP-IL. Main usage is to interface the HP-IL loop to electronic circuitry.

> Can the PIL-Box be used to control a HP-IL instrument (such as the HP3468 or HP3421) from a PC?
Yes, an example of software code is provided below: ILCtrl is a simple example in Visual Basic controlling HP-IL devices.
I don’t provide a complete solution, but you can use this code freely to build your own application depending on your needs.

> Is a special software needed on the HP41 (or HP71, or HP75) side to load/save programs on PC with the PIL-Box?
No, you just need to use regular HP-IL commands (HP-41C: from the HP82160 HP-IL module, HP-71B: from the HP82401 HP-IL module).

> Is there any support of the PIL-Box for Linux or OSX?
The PIL-Box itself is fully supported using the FTDI drivers.
For the ILPer software, there are solutions available for Linux or OSX, see below.

> The PIL-Box doesn’t seem to answer to the FINDID/ID/AID (HP-41C) or DEVADDR/DEVID$/DEVAID (HP-71B) commands. Is there an error?
The PIL-Box itself is only an interface or translator and doesn’t respond to these commands. The ILPer software on PC side must be running to get answers to these commands.
The PIL-IO is a real HP-IL device that answers to these commands.

> Can the PIL-Box work with the Portable or Portable Plus computers?
YES! See my Portable Plus page.

Support Documents and External Technical Resources

HP-IL / Serial translator – technical description (pdf file – Oct. 2008). This file documents the basis of the PIL-Box principle.

PIL-Box schematic (full) (Nov. 2008). Complement to the technical description.

PIL-Box advanced notes PIL-Box advanced information and limitations (pdf file – March 2018)

PIL-Box firmware hex and source files (for documentation and DIY projects only, see readme file - Nov.2015)

PIL-IO firmware hex and source files (for documentation and DIY projects only, see readme file - May 2014)

How to solder the HP-IL cables on Etienne Victoria’s site (alternative to the screw connector)

Custom PIL-Box modification with a HP-IL connector panel (Raymond Del Tondo - Jan. 2020)

DIY HP-IL Device Connector A 3D printed solution for the PIL-Box (Duncan Burgess-Parker - April 2020)

Using pulse transformers  A DIY modification of the PIL-Box - Sept. 2020

PIL-IO Interfacing  A custom PIL-IO modification and installation in a box (Duncan Burgess-Parker - April 2021)

3D printed panels for the PIL-Box  A PIL-Box user created 3D printed panels and released his design to public domain (thanks to him - October 2023)


ILPer: HP-IL Peripheral emulator

ILPer is a HP-IL peripheral emulator using the PIL-Box. It provides an emulation of a mass storage unit and a generic alphanumeric non-graphic printer. It also provides a HP-IL scope that was very useful to test the PIL-Box and identify some tricky problems.

I originally wrote ILPer in Visual Basic to support the first PIL-Box users.
Later on, Christoph Gießelink ported my sources with several improvements to Visual C.

The latest version of ILPer is available on Christoph’s site:

HP-IL Page of Christoph Giesselink

Christoph’s version doesn’t require the installation of the quite big MS NET Framework that was needed for my Visual Basic version and provides several fixes and improvements:
the ILPer window can be minimized and restored without problems,
the COM port can be selected from a list of available ports,
there is a “open file” button to select the disc image file,
and finally the settings (COM port and speed, image file name) are saved.

New: versions 2.x now provides two mass storage units, the basic generic printer and the DosLink interface for easy file import/export.
New: version 2.2 now supports the 230 kbps com speed (for PIL-Box 2.1 and later) and uses automatic speed detection (no more manual com speed settings).

Using the DOSLink device (ILPer 2.x):
This Allschwil 2014 meeting presentation explains how to use the Doslink device with Emu71, but is also applicable to a real HP-71B and ILPer.

My Visual Basic version is still here for documentation:

ILPer – Version 1.35  - VB version (zip file)

ILPer – Installation and Documentation my original documentation (pdf file)

I’m a quite unexperienced Windows programmer (I prefer to program calculators or microcontrollers), so I chose Visual Basic Express Edition (a free language) to quickly build a Windows application to support my PIL-Box. I used the HP-IL code taken from my Emu41/Emu71 emulators, but ported from C to VB.

Source files are included. You are welcome to improve the ILPer software, or write completely new software to support the PIL-Box.
I didn’t document yet the details of the protocol between ILPer and the PIL-Box, but it is very simple and can be understood by looking at the source file MainForm.vb.

Historical note: this ILPer version is a reincarnation of my ILPER software I wrote initially in the mid 80’s on a my 6502 system (based on a OSI Superboard 2 computer with personal extensions) equipped with a custom HP-IL board, to emulate mass storage and display units for my HP-41C and HP-71B...


Support of Linux and OS X users:

ILPer has been ported to Linux by Christophe Gottheimer:
 ilper/linux 1.35.2 available in the hp41.org Utility Library.
(You may need to register – it’s free – to download ilper/Linux from hp41.org)

Running ILPer on OS X:
The procedure to run ILPer on OS X systems has been described by Juergen Keller here:
 Make PIL-Box ILPer program run on OS X in the old HP Articles Forum of the Museum of HP Calculators.
See also this more recent discussion: Mac OSX and PIL-box


ILPer Python version:

A Python version, potentially running on Windows, Linux and Mac OS/X is available here:
 pyILPer : Virtual HP-IL Devices (Python version).


ILCtrl: A simple HP-IL controller

ILCtrl is a demonstrator of a simple HP-IL controller using the PIL-Box:

The example just above illustrates the use of the PIL-Box with a HP3468A multimeter, a HP9114A disc drive and a HP-71B (used in device mode):

The trace window shows the results of the following actions:
Read the device IDs of the 3 devices,
then put the HP-IL devices in remote mode,
then take 3 measurements from the HP3468A,
then send a "HELLO PILBOX" message to the HP3468A display,
then read the status byte of the HP9114A (no disc was inserted),
then send a "beep" command to the HP-71B (the HP-71B wakes up and beeps!),
then send a "off" command to the HP-71B (the HP-71B turns itself off!),
then clear all HP-IL devices (HP3468A display returns to default mode).

Version 1.0:

ILCtrl – Version 1.05  (zip file) – Jan. 2019

Source files (Visual Basic) are included. It illustrates how easy it is to implement basic HP-IL controller capabilities on a computer using the PIL-Box, it’s actually easier than to implement device capabilities.

A version in C++ is available on the HP-IL Page of Christoph Giesselink

ILvlif: A LIF media viewing tool

ILvlif is another demonstrator of using the PIL-Box to control a HP-IL mass storage unit.

ILvlif allows to access LIF-formatted media using the PIL-Box and a HP9114 or HP82161(*) drive. It displays the information from sector 0 of the tape or disc and the content of the catalog. Most LIF file types used by the HP41, HP71, HP75, HP series 80 (HP85/87), and HP9000 (series 200/300) Basic and Pascal workstations are recognized.
(*) the HP82161 cassette unit has not been tested.

Version 1.1 now has a command to make an image of a LIF disc, to save old physical LIF discs to image files for use with ILPer.
It supports the 230 kbps com speed with PIL-Box firmware 2.x (recommended).

Version 1.1:

ILvlif – Version 1.11  (zip file) – Dec. 2016

Source files (Visual Basic) are included.



HP-IL general information and documentation

http://en.wikipedia.org/wiki/HP-IL General description of HP-IL

http://www.fortitudine.com/~coryc/html/hpil.html An overview of HP-IL

http://www.hpmuseum.org/software/swcdp.htm#op  Documents related to HP-IL on MoHPC's DVD, including HP-IL specifications

http://www.hp41.org/HPIL.cfm Extensive HP-IL documentation, including detailed HP-IL specifications

http://www.hp-collection.org/hpil.html  Collection of HP-IL devices and interfaces


http://www.hpmuseum.org/forum/thread-11437.html The HP-IL Compendium by Sylvain Côté (highly recommended)

http://hp.giesselink.com/hpil.htm  HP-IL Page of Christoph Giesselink (highly recommended)

http://www.mh-aerotools.de/hp/hp-il/index.htm How to Make Your Own HP-IL Cables, by Martin Hepperle.

Joseph Horn/Online LIF Disk Project  The OnLine LIF-Disk Project (O.L.D.). See the presentation video here by J.Horn himself (2014).

HP-IL Files: Where, What, Why, How, etc. Article on the MoHPC (2000)

Presentations, articles and books

How fast is HP-IL ? My presentation at the Allschwil 2016 meeting (pdf)

HHC14_HPIL.pdf  Bob Prosperi “Virtual Loops, PILs and LIF” presentation at the HHC 2014 Meeting (pdf). See the video here.

HHC 2009 HPIL.pdf  Egan Ford “HP-IL 2009” presentation at the HHC 2009 Meeting (pdf)

Control the World with HP-IL - The Friedman Archives (1987)

HP-IL Update - Jim De Arras, Atlanta Conference (1985)

http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/hpjindex.html#1983 HP Journal issue on HP-IL (Jan. 1983)

http://www.hpmuseum.net/exhibit.php?catdoc=9 "The HP-IL System, an Introductory Guide" (1982)

http://www.hparchive.com/Bench_Briefs/HP-Bench-Briefs-1982-03-04.pdf "New HP Interface Called HP-IL" (1982)



If you want to have more information on my HP-IL activities, please contact me :

J-F Garnier, 2023