HP-41 Bar-Code checksum algorithm.


Hi again!

Does anybody here know how is the HP-41 Bar-Code checksum calculated?... (And wants to share this info :-)

Thanks in advance.


The "Make You own HP41C Barcode" Manual is included in the MoHPC CDROM collection. The Basic programs are essentially unreadable (what a horrible language), but the algorithms and flowcharts are all there.

The manual is in file packs/hpbc.pdf



My 'LIF Utilities for Linux' package includes programs to produce HP41 program and data barcode, and of course they calculate the checksums. These programs come as (hopefully) commented C
source code, so you might be able to figure out the algorithm from there. It'll make more sense if you have the 'Create your own HP41 barcode' book, though



Thank you both for your comments. Finally I've got the desired algorithm and... it was here at MoHPC!!:


An article posted by Dan McDonald (my gratitude for him), wich includes an Excell file "HP_ListA.xls" with an annotated macro for the barcode generation.

The "real thing" is fairly easy: (sum of bytes 2-16 (or the last byte if less in row) + previous row checksum byte) MOD 255.

Again, thanks and cheers from the middle of the Athlantic Ocean ;-)

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