HP-41 Literature - German

[Martin Hepperle]

(11-12-2014 08:35 PM)aurelio Wrote:  Did you try to read with a wand any of the barcodes printed from your scan?
I printed five random pages and I found that a few works but not all...checksum problem...... the quality of the scan is the same.....i printed with a laser b/w printer...is there any trick?

Aurelio,

this is interesting.

Unfortunately I don't have a HP-41 with wand. That was the reason why I wanted to develop my own solution.

I tested the barcode printed from my program as follows:
- printed to a PDF file (Acrobat PDF Writer)
- exported via Acrobat to a PNG image
- re-read the PNG images with my program (no checksum errors)
- I read the resulting .p41 program file into the V41 emulator.

I think that my checksum code in the reader portion is correct as it works nicely for all barcodes I copied from books, PPC, other barcode printers etc.
As I can read back my own barcodes I think that the checksum algorithm would also be o.k.
Concerning the bar dimensions I followed very closely the HP documentation so this should be o.k. too.

But: after reading your comments I crosschecked my code and I found an error in the calculation of the number of bytes for commands broken at the end of a barcode row and continued on the next row.
I have now (27 Nov) updated the .zip archive accordingly with a fixed version. Maybe you can give this another try?

Questions:
- do you have the possibility to print to a PNG file or produce a PNG file via Postscript and Ghostscript/Ghostview? Then you could re-read the barcodes with my program to check whether this works for you as in my case.
- can you send my your problem program in RAW, DAT or HEX format and tell me which rows pose a problem when reading back? I could then compare the barcode images with bar copdes produced by other programs.

Martin