Creating the hydroterm
Readers of the evolving Waterfalls and Glass, Merrimac Murder Mystery #1, may have noted the unusual terminal devices called 'hydroterms' that spring from an alt-history that mixes equal parts an imagined forgotten Gallic ingenuity, a casual and vaguely sinister 'better living through chemistry'-type toxicity from fictional American conglomerate Denbridge, and the daffy Yankee thrift of pioneering New England tabulating firm Merrimac. Pioneers of revolutionary and totally imaginary computers.
I have no idea how the hydroterm works. Sorry. I know that both the power needed to run the term and the information required to feed it come through a single hydraulic port without a return and that the hydraulic lines are filled with 'Denbridge fluid'. There are probably a lot of different Denbridge fluids, each with the properties I need for that narrative application. They are almost certainly fluorinated 'forever chemicals' regarded as a mistake now and a miracle then. For the terms, the fluid may be engineered to have a faster speed of sound or some other application-specific property.
The terms are printing-type machines, like teletypes, but they use some kind of special coated paper that was expensive in wartime and obsolete now. Also, the printers are silent. My working models here are thermal printing with special paper, as used still in some cash registers, some kind of catalytic printing with a catalyst-coated type block and special paper, or some kind of pressure-sensitive paper. I lean toward catalytic printing, because pressure-sensitive would make it a bit too much like renting a Ford Escort from Hertz in 1985 with triplicate forms. Perhaps it's some hydro-tribo-electric thing that's a totally impractical precursor to the laser printer.
To think further about this, I've been playing with some older printers. I would love to have a TI Silent 700 thermal teletype but I live in a house too small for all the esoteric stray computing devices that I might wish to have follow me home. I'm interested also in obsolete spark printing devices of the type available for some of the lowest-end home computers and some of the highest-end calculators.
While the movie 'Office Space' may have given us a shorthand for collective frustration with printing – "PC Load Letter? What the fuck does that mean!?" – it misses that printing was always hard. PC Load Letter, a common HP LaserJet message of the era, means "Paper Cartridge" Load Letter. The printer is out of paper. Perhaps a more vernacular approach would have been better. Perhaps HP's position as an also-ran in the early PC market confused them as to what consumers thought the term PC might represent. The HP 85 was the knife HP brought to the PC gunfight. It was classy, well made, and as practical as a watch with a second hand that marked 100 seconds a minute. Obviously, it had both a built-in thermal printer and a proprietary cassette drive with only a single media supplier. Obviously.
Whatever the ultimate impact of the HP85, it was quite something that computers were starting to show up with working printers on day 1. Consider poor Charles Babbage, inventor of the computer printer. His first printer, designed for the Difference Engine, wasn't delivered until 2002 – over a hundred and fifty years after it was designed. Babbage's design captured a detail that has bedeviled printer makers since. The printer alone contained 8000 parts. While the parts weighed on average around a pound each, the enormous mass of it was split mostly between heavy and inconvenient bits and small fiddly bits at the absolute edge of period manufacturability. This pattern in printing didn't change much for a long time. In the inkjet era, the fiddly bit became the printheads and inks that support drops of a few picoliters.
If I don't have space for a TI Silent 700, I certainly don't have space for a Babbage. What I do have space for is a DYMO LabelWriter 450 Duo. It's a little thermal printer used mostly in small business for printing shipping labels and paper visitor badges and the like.
The DYMO normally prints a whole label at a time, but I wanted to see if I could turn it into an interactive line printer and have the kinds of quiet interactive sessions that the Merrimac users might have experienced. The short answer is yes, but I would never have gotten there without a helpful technical reference manual from DYMO.
After this warning, I knew that the printer and I were going to be friends. It prints a raster line at a time using ordinary household bytes that you provide for yourself and about one framing byte per line. It's a 300 DPI machine printing on paper about 2 inches wide. Probably best paired with a line magnifier for interactive use. In the specific case of the DYMO, the print head is buried pretty deep in the machine, so several lines have to be advanced before text can be read above the tear bar. If I can figure out reverse feed on the printer, I think I can make this work interactively.
Speaking of framing, a friend offered this portrait-oriented view of the modern printing scene:
I like the idea of a driver being something that you don't really need if you are a responsible adult on good terms with your printer.
Yes. Part of the reason this driverless DYMO has survived into this era is that it's the type of device that gets connected to cash registers and alarm systems and parking garage kiosks and a hundred other embedded situations beyond DYMO's ability to support. Maybe one of the best parts of the explosion of home computers was that so many third-party peripherals were in the same situation. No driver, but maybe a few pages of generic BASIC pseudocode to suggest how it might be used.
As for the hydroterm? Well, I can promise that if I ever build the turbofluidic drive interface board necessary to talk to one from a Raspberry PI, there isn't going to be a CUPS profile distributed with it. As for Apple AirPrint support? It's a hydroprinter, not air. That doesn't even make sense.