Telxon Machine

[mstone3]

Hello, I recently acquired a Telxon PTC-610. This is an interesting device known as a portable tele-transaction computer used for inventory management (probably in the mid 80's through the early 2000's). I worked in a store that used this machine to read product bar codes with a wand and then transmit orders to the warehouse. The user would dial a phone number and hold the receiver to the back of the machine where an audio signal transmitted the data. I'm interested in being able to decode/demodulate this audio signal but have no real idea of how to go about it. My guess is that the machine uses audio frequency shift keying, but I have no information about the protocol or transfer rate. I haven't had much luck finding specs of the machine online. Thanks for any suggestions out there on any software or other ideas that I could learn about on how to decode its signal.

 

[rjenkinsgb]

It will almost certainly use a standard dial-up modem format, at 110, 150 or 300 Baud, which was typically the limit for acoustic coupled modems.

Look at the details for the Bell 212A or V21 modem standards.

eg. This gives details of the 212A standards:

http://vtda.org/docs/computing/UDS/Prelim_Spec_212A-compatible_Modem.pdf

Page 3 -

Frequency shift keyed on a bit per bit basis. The average carrier frequencies will be 1170 Hz ± 6 Hz for the low channel and 2125 Hz± 6 Hz for the high channel. •

The actual data transfer could have been plain text, or using a protocol such as Kermit or XModem.

Kermit - What is it?

www.kermitproject.org

XMODEM File Transfer Protocol - GeeksforGeeks

A Computer Science portal for geeks. It contains well written, well thought and well explained computer science and programming articles, quizzes and practice/competitive programming/company interview Questions.

www.geeksforgeeks.org

 

[mstone3]

Thank you very much for this information!