Strange though it may sound, I’m fascinated by device I/O capabilities.

If we think of humans as a form of a device, our “Inputs” are our senses: sight, hearing, smell, taste, touch (and the various attributes conveyed through the skin e.g. temperature or humidity), and our “Outputs” are our vocal chords and the interactions we can have between our bodies and the physical world. It’s a very robust set of capabilities.

Other devices are not so lucky. Take UPC scanners, for example. Many of them can only scan barcodes for input, and display two lines of text as output. Imagine having the brain of a human being but being able to interact with the world through only these two things!

While a scanner may get plugged into a more expressive device with buttons, larger screens, or even a full terminal, by its purpose it may not be near a machine when its user requires it to do more than scan items. For this, UPC scanner designers devised various clever schemes to augment the device capabilities with appropriate conventions. And I discovered one of them quite by chance.

If you spot a UPC scanner out in the wild (for example, in a department mall such as Bloomingdale’s, as was the case for me), try having it scan the following barcode. Prepare to be (somewhat) amazed!

Try scanning this barcode with a retail UPC scanner. This works only for some scanners…

This makes for a good party trick, assuming the party is happening at a department store and you happen to have this barcode. (I, for one, carry a printout in my wallet, just in case).

“Control codes” are an old invention but it’s exciting to see one used in such a common scenario as shopping. Here is another one I discovered. Kudos for those who find more, I am pretty sure one can find some user manuals with all the control codes per model of scanner.