DB25 #16 — thunk

In classy computer languages, a thunk is a nullity function used to encapsulate and defer a computation until its value is actually required. It’s a high-concept name for what the rest of us know as procrastination.

I’m an admirer of procrastination in all its forms. Just look at this series! A year to get through 25 vignettes about the DB-25 and we’re only on 16 in the middle of November.

Do thunks exist in hardware? Well, after a fashion. When I was in middle school, the closest thing to a network was a chunky metal box that let the adminstrators in the front office choose which PC was connected to the printer. Not a print server, not an automatic switch, but a knob connected to a 25-pole rotary switch making individual connections from each wire of a central DB-25 port to each of four satellite ports. Thunk. The box had to have some extra width just to counter the torque of turning the knob. Think of how many decisions you could postpone with that baby. Is it for parallel printers, RS-232, or fireworks? Yes. Is it one-in to four-out or the other way around? Yes. Is it for PCs or Macs? Yes. Do you need to buy new software or make any decisions or do anything? Not really. In fact, you can just leave it in its box until you get sick of moving cables around manually. Does it need batteries? No. It’s wrist-powered.

A peripheral like that sounds almost too good to be true. How does it stack up? In my experience, it works pretty well. If you are using it to share a printer in a workgroup, you print your document and then flip the switch once you realize that nothing has happened. Then you print it again. It’s just as simple when using it to switch between two printers on a single PC. Wait for your job to start rolling out of the wrong printer, then switch.

It’s like a cross between regular old procrastination and branch prediction.

The boxes got more or less left behind by USB and then WiFi. Blah, blah, inexorable march of technology — but really. WiFi is as cheap as a DB-25 connector these days. The boxes themselves are still available, though for more than you might pay for a cheap printer. While they may not be worth your cash, they are worth a little nostalgia as they represented the end of the filing cabinet sheet metal era of computer design. If that special someone on your Christmas list already has a typewriter and a turntable, consider a daisy wheel printer and a switch box.