This definitely ranks in my top 10 hacks of all time, and I might even
consider it for the top of the list. What it does is simple, but it does
it very elegantly and has a cool twist, that of using user-defineable fonts
on the VT220 terminal to display USPS barcodes. It obviated a very
primitive diagnostic routine built into the real-time control task MA.
Wnen the PDP-11's were upgraded (or downgraded, as many believe) to VAXen,
this capability was lost, and for me it was sorely missed. The barcode
readers were the cause of numerous operational headaches on these machines,
and diagnostics were still in the dark ages.