Thanks for that write up and explanation Peter! It was great to open my email, sit down with my coffee, and learn something new today :)
--Brad On Wed, Nov 2, 2022 at 2:52 AM Peter Noeth <[email protected]> wrote: > If your BCR wand came with the instruction book, then the information in > it is correct. There was a supplemental BCR driver tape, 26-3828 that added > drivers for Codeabar, Interleaved 2 of 5, and UPC-EAN, that was available a > few years after the M100 bar code reader was available. It wasn't > advertised much though, just showed up one day hanging on the wall at my > local Radio Shack (with Computer Center) store. I didn't get it at the time > because I didn't have a use for it, but I should have. > > A little history ..... Radio Shack licensed the BCR wand from Hewlett > Packard. It is the same wand as HP sold for the HP-41 calculator, just says > Radio Shack on it. The LED is dim, and has to be enabled by pushing the > button on the wand, because it was originally powered by the "coin cells" > of the HP-41, so needed to be a low power device. > > Since it does not have the "ruby tip" that the industrial wands use, angle > of the wand to the paper barcode is more critical, so the Radio Shack > recommendation of 10-20 degrees back from perpendicular to the barcode > label is important. And without a proper lens, it is important to not press > the wand onto the barcode too hard while reading. Doing so will wear the > tip, changing the distance from the LED/Photo Diode module to the barcode > label causing mis-reads due to being "out of focus". That is why Radio > Shack sold replacement "tips" to be used when you "flat spotted" the wand > tip from excessive wear. Just soft ABS plastic. > > Also, since HP designed the wand to read paper labels, the dim LED > prevents using the wand effectively on modern UPC codes of food industry > items, where the barcode is printed on mylar, like potato chip bags. It > needs a lot of contrast between the light and dark bars to work correctly. > Works best with black and white bars on "semi glossy" paper. > > How it works ..... The M100 driver measures the times between the high and > low transitions the wand outputs while scanning the barcode. These are then > compared with a table of "times" for a match. if one is found, that ASCII > character is then sent to your BASIC program when reading the "WAND" > device. The driver allows for about a 5% tolerance in the transition times, > so scanning speed is important. Once you train yourself in the correct > scanning speed, it works quite reliably. > > I have the Radio Shack BCR wand, but only for the completeness of my > collection. For actual use I use a Unitech MS120-NTCB00-NG wand. This is an > industrial type in a metal body with a hard "ruby tip" lens. It has > the same "locking" 9-pin D connector and is "plug-n-play" with the Radio > Shack wand. Much brighter LED that is always on. It can reliably read the > low contrast barcodes used in the food industry, even when the dark bars > are in some color other than black. I use it often for keeping a "food > pantry" and "wine bottle" inventory database with my Tandy 102. Only > drawback with it is that the LED draws more current and is always on, so > while I am "inventorying" the pantry, I usually use an external battery to > power the computer. > > Regards, > > Peter > -- -- Brad Grier
