03-31-2022, 09:07 AM
Those who own a barcode reader for their HP-75D probably never made use of it.
To remedy this situation, I have written a small "C" program which can be used to generate barcodes from ASCII text.
These codes can be printed out and then read into the HP-75 with an small BASIC program.
I also tried to read them directly from a TFT notebook screen, but this did not work.
The wand needs a reflective black/white surface because of its own LED light source.
I guess, that a device with an E-paper display, like an Amazon Kindle, would work too, if the documents were scaled so that one narrow bar matches exactly one column of pixels.
The barcode generating "C" program has been written with Turbo C on MS-DOS in VirtualBox, but it can also be compiled under Windows or any other system with a "C" compiler.
Even if the character range is currently limited to the 7-bit ASCII set, it is possible to read textual data or programs into the HP-75 without the need for a mass storage solution.
If you have a HP-75 pod, the required decoder ROM is built into it, otherwise you need the Barcode ROM module.
[With the sources available, one could even think about extracting the 3 of 9 reader routines into a LEX file for HP-75Ds without pod or Barcode ROM. However, the firmware is relatively complex and large, so I did not do this.]
Note that the conversion requires some memory. The barcode ROM asks for about 1400 bytes of RAM and both, the TEXT as well as the BASIC file will be present in RAM during the conversion.
Also note that my reader program assumes that each line of barcode starts with a line number. Of course, this can be changed easily.
Martin
Edit 1-APR-2022: small correction in 3of9.c program and documentation - ZIP archive updated.
[attachment=10488]
To remedy this situation, I have written a small "C" program which can be used to generate barcodes from ASCII text.
These codes can be printed out and then read into the HP-75 with an small BASIC program.
I also tried to read them directly from a TFT notebook screen, but this did not work.
The wand needs a reflective black/white surface because of its own LED light source.
I guess, that a device with an E-paper display, like an Amazon Kindle, would work too, if the documents were scaled so that one narrow bar matches exactly one column of pixels.
The barcode generating "C" program has been written with Turbo C on MS-DOS in VirtualBox, but it can also be compiled under Windows or any other system with a "C" compiler.
Even if the character range is currently limited to the 7-bit ASCII set, it is possible to read textual data or programs into the HP-75 without the need for a mass storage solution.
If you have a HP-75 pod, the required decoder ROM is built into it, otherwise you need the Barcode ROM module.
[With the sources available, one could even think about extracting the 3 of 9 reader routines into a LEX file for HP-75Ds without pod or Barcode ROM. However, the firmware is relatively complex and large, so I did not do this.]
Note that the conversion requires some memory. The barcode ROM asks for about 1400 bytes of RAM and both, the TEXT as well as the BASIC file will be present in RAM during the conversion.
Also note that my reader program assumes that each line of barcode starts with a line number. Of course, this can be changed easily.
Martin
Edit 1-APR-2022: small correction in 3of9.c program and documentation - ZIP archive updated.
[attachment=10488]