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hp82240

General

The Java based HP 82240 is a command line printer simulator for the Hewlett Packard HP-82240A/B infrared printer. It will decode printer commands received via a serial port, and produce a text and a bitmap file.

The printer commands are text strings, escape sequences and line feeds, encoded in a character set as defined by HP. See Printer Character Sets for details.

Note that the simulator does not understand the raw infrared pulses generated by the HP calculators. It needs special hardware (see below) that interprets these pulses and converts them into bytes.

The output of the simulator consists of two files:

  • Hp8224-Text.txt: Any text that was sent to the printer, converted from the HP character set into UTF-8.
  • Hp8224-Image.png: Text and graphics as they would look on the printer paper.

To illustrate, see the actual printer on the left, and the generated bitmap file on the right:

Printer Simulated Output
HP 82240A printer Self Test

More examples are available here and here.

Acknowledgements

  • Thanks to Christoph Gießelink: He develops a Windows based simulator of the HP printers 82240A/B and 82143A. The bitmaps for the printer characters directly come from this simulator (See hpcalc.org for the full source code)
  • Thanks to Martin Hepperle: He developed the first "Red Eye" reader, see "Hardware" section below.
  • Thanks to Meindert Kuipers: His version of the "Red Eye" receiver is the one that I am using.
  • Thanks to Christian Vogel; His avr-redeye project allowed me to send any print commands that I like to my real HP 82240A printer and observe its behaviour.

Installation

Copy the hp82240.jar file to a convenient location. Make sure to have a Java 17 or higher runtime available on your system. Then, start the simulator with:
java -jar hp82240.jar [-p=comport]
This will start the simulator and open the com port for reading. Any existing output files (Hp8224-Text.txt and Hp8224-Image.png) will be overwritten on application startup.
When you are done with your session stop the simulator with Ctrl-C. Save away the output files for later use.
If you omit the com port, the simulator will attempt to auto-detect the correct port.

Quick testing

For some quick testing, the simulator can work with input files. To produce a self test, one can use this: java -jar hp82240.jar -i selftest.yaml. The files are the same ones as used in the Red Eye sender (see below). The file format is not explicitly documented, but should be self explanatory when looking at the provided samples.

Receiver Hardware

To receive the infrared pulses from an actual calculator, and convert this data to a serial stream, special hardware is required. I built a receiver based on this guideline, which in turn is a modified version of this guideline.

Comparison with other simulators

This simulator is currently limited in functionality, supporting only the HP 82240A/B printer, and lacking a graphical user interface. Its main advantage is that it runs on all platforms supporting a Java 17 or higher runtime, including ARM devices such as the Raspberry Pi.

Validation on a real HP82240A printer

To validate and compare any output generated by this simulator with the output from a real HP 82240A printer, one needs to be able to send very specific strings / graphic codes to the printer. The real calculators are only of limited use here, because their firmware prevents certain issues to happen. For example, lines that are too long (longer than the printers buffer) get Line Feeds added by the firmware.

Therefore, a tool has been developed that allows to send any sequence of bytes that one wants to a serial port. On this serial port a piece of hardware is required that generates the "Red Eye" pulses that the printer understands.

Sender Hardware

I am using this project with an Arduino clone and a simple IR diode: avr-redeye. The project is a few years old, but it works perfectly right out of the box. Note that you can't use the Arduino IDE to compile / send, because this is pure C code and not an Arduino sketch. On the Mac I installed two tools:

  • brew install avrdude
  • brew install avr-gcc

I had to slightly adapt the PROGRAMMER_DUDE part of the Makefile to
PROGRAMMER_DUDE = -P/dev/cu.usbmodem4101 -carduino -b57600, and then it worked right away.

For the first test I used a genuine Arduino Uno, and found that this device sends spurious bytes (0xF0) when the serial port gets closed (which happens automatically at the end of the application). So if you see strange characters on your printer, try with a different type of Arduino. Here is the device that I am using now:

IR Sender

Sending print commands

The tool is invoked as follows: java -cp hp82240.jar ch.erzberger.emulation.sender.RedEyeSender. It will then tell you the necessary parameters. Some sample files are provided in the documentation/sampleoutput directory.

Stdin, Stdout

The simulator can read from Stdin instead of from a serial port. Use this if you have e.g. an emulator of a calculator that sends print output to Stdout. To test, use the RedEyeSender, sending to StdOut:
java -cp hp82240.jar ch.erzberger.emulation.sender.RedEyeSender -p=stdout -i=selftest.yaml | java -jar hp82240.jar -p stdin

License

HP82240 - A Java based HP 82240A/B Printer Simulator Copyright (C) 2023 Martin Erzberger.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License Version 2 or any later version, as published by the Free Software Foundation.