The Museum of HP Calculators

HP Forum Archive 13

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HP41 barcode Wand
Message #1 Posted by Meindert Kuipers on 13 June 2003, 3:56 a.m.

I have been looking for a barcode reader on Ebay, but these are pretty rare and expensive. The wand is mainly meant to prevent typing in a whole lotta code and then transfer it to my PC for more permanent storage. Has anyone ever come up with the idea (and solution) for scanning barcode with a flatbed scanner and making a (PC-based) program to read the barcode straight into the PC?


HP41 barcode: Another issue
Message #2 Posted by Vieira, Luiz C. (Brazil) on 13 June 2003, 9:46 a.m.,
in response to message #1 by Meindert Kuipers

Hello, Meindert;

your idea brought another one to my head: why not using commercialy available barcode readers and then create a custom HP41 decoder (or coder)? Aligning the original image, scanning it, reducing image errors and the like would also be fast and SW demanding; I think current PC-based wands and related drivers/software may generate a stream file with a sequence of bytes from the HP41 barcodes. A single program would break the line into bytes and combine them to form an HP41 valid sequence.

What do you think? You'll need more time to read the barcodes (to wand them) but obtaining final listing without much errors is easier. I used to scan program hardcopies and unse an OCR to retrieve ASCII data. In some cases, when original hardcopy had enough contrast and darker printing, a few instructions needed to be corrected. In some cases, with old paper with few contrast and failing characters, keyining in the program was easier. After that, 41UC could generate any equivalent, even .PS barcodes.

Hope this adds a bit to yout original and very good idea.

Best regards.

Luiz C. Vieira - Brazil

Re: HP41 barcode: Another issue
Message #3 Posted by Andrés C. Rodríguez (Argentina) on 13 June 2003, 5:51 p.m.,
in response to message #2 by Vieira, Luiz C. (Brazil)

Luiz: I think that the coding used by the HP41 does not respond to any of the usual "symbologies" read by commercial wands or barcode scanners of today. If the decoding is done in the scanner, and just serial (decoded)data is passed to the host, there is little chance we can go farther with this approach. If the scanner has a "raw" mode which senses and send upstream just the transitions, then a software piece could take care of them...

Just my 0.5 cents

Re: HP41 barcode: Another issue
Message #4 Posted by Johnny Billquist on 14 June 2003, 3:45 a.m.,
in response to message #3 by Andrés C. Rodríguez (Argentina)

You are correct, Andrés. The 41 barcode use a coding I've not seen anywhere else. It's a rather simple coding, though. The 41 only uses the black bars, which are either narrow or wide, to represent 0 and 1. Most barcodes use both the bars and the gaps between bars.

I have a book that fully describes the 41 barcode format.

Re: HP41 barcode: Another issue
Message #5 Posted by Hans Brueggemann [GER] on 14 June 2003, 3:52 a.m.,
in response to message #2 by Vieira, Luiz C. (Brazil)

really nice idea. however,i think it's really easier to take a cheap flatbed scanner instead of an industrial wand, because nowadays even new scanners cost only around $40 AND come with a twain interface. i am close to finishing version 2.0 of my HPILCOM (a small piece of software that faciliates data transfer to/fro a PC and a HP-41C and is solely controlled by the 41). i'll be digging into it to find out whether this feature can be implemented into the program.

cheers, hans

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