A USB Typewriter?

jashmenn asks: "In my search for a furthering of the arts combined with technology I recently had the idea of hooking up an electronic typewriter to my USB port. The idea is to eventually write a script that would automatically send the text of emails to be typed on the typewriter. Does Slashdot have know of resources I can use for combining new and old school technologies such as these?"

Comments

Re:Printer?

[rednip]

What purpose would this USB-Enabled Electronic Typewriter serve?

I've got an idea... spooky typewriter from hell. Can you imagine having a old fashioned typewriter knock off a note like...

I'm watching you.

It would be perfect during a seance.

Low IQ today

[Anonymous Coward]

Geez, the collective Slashdot IQ is particularly low today. Let's see, so far I've seen people asking why bother, use a daisy-wheel printer, use a teletype, and plenty more of "why".

For pete's sake, people, he said he was doing this for "art". I think he's probably already considered other printer options (daisy-wheel, teletype, etc.) and wants to have a typewriter, for the look of it.

At one point, I had an IBM Selectric typewriter that could also be driven by a parallel port (though the encoding was odd -- it might have been EBCDIC, come to think of it). That might fit the bill, though I've no idea where to find one. It'd certainly look cool. Be sure to send us a follow-up when you get this working. :)

ideas and problems

[dutky]

If you want to convert an old electric typewriter into a USB input/output device you will face a few challenges.

First, traditional electric typewriters were mostly mechanical beasts (electric, not electronic) actauted by springs and levers with the user's finger motion enhanced by a flywheel. Only the flywheel was driven electrically, all the rest was mechanical. This means that there are no electical siganls generated when the user presses a key, just a series of levers and catches that connect the flywheel with a typearm and some mechanism to advance the carriage. Even the carriage return and platen advance was mechanical: as the carriage advanced a spring was stretched. The carriage return released the carriage, which was pulled rapidly to the right by the carriage return spring. When the carriage slams into the stop at the rightmost end of travel, a pin or wedge caused the platen to advance to the next line. The driving force for the platen advance was the momentum of the returning carriage.

In theory, you could instrument the typewriters mechanics with sensors to detect key presses and carriage return events using optical or electronic sensors. The sensor states would be fed into a microcontroller which would format them for communication over the USB port. This would allow you to use the typewriter as an input device.

Using the typewriter as an ouput device, however, is more complicated. You would actually have to add a bunch of actuators (solenoids, for example) to the typewriter's mechanism. I can think of a few ways to do this, but they are all labor intensive (I'd mount the solenoids vertically beneath the typewriter and connect each solenoid to the actual key it drives by a wire or shaft. When the soleniod is activated, the key is physically pulled down, just as if the key had been pressed normally.) and power hungry. Again, a microcontroller would be used to accept data from the USB port and translate it into signals to actuate the solenoids. The MCU would need to keep track of, or be able to sense, carriage position and put suitable delays between keystrokes to prevent jamming the device.

It all sound quite fascinating, but of very little practical value. It is likely to be a bit costly as well, but that shouldn't stop the dedicated hobbyist. Of course, for a lot less effort and money you may still be able to find an old ASR-33 teletype with an optional RS232 interface (most ASR-33's used current-loop interfaces, which are not directly compatible with RS232). These old teletypes are pretty much what you are looking for, ready-made. You may freely substitute a DECwriter for the ASR-33 and I think there may be some versions of the IBM selectric that also fit the bill.

We did this in the '80s

[RobertB-DC]

I say we, but it was really my dad (an electronics technician) and my stepmom (a computer programmer) who did it. They took the TRS-80 parallel port output, which was a slow, simple 8 data lines and a clock, and connected it to an IBM Selectric.

The Selectric was already wired to accept electronic input, but not in ASCII. It expected tilt-and-rotate codes, which were directly transmitted to the golf ball shaped typing element. To translate the TRS-80's ASCII to tilt/rotate codes, my parents drew up a table of equivalents. Then, my dad came up with a way to logically combine the TRS-80's output with values stored in an EPROM to get the tilt/rotate codes.

I ended up using the computer for my typing class homework. Fortunately, the teacher didn't mind that I was writing BASIC programs like this:

10 A$ = "THE QUICK BROWN DOG ATE THE LAZY FOX"
20 FOR I% = 1 TO LEN(A$)
30 POKE addr, ASC(MID$(A$, I%, 1))
35 some sort of delay for the ball to get repositioned
40 NEXT

I thought I was getting away with something... but my teacher wisely realized that I was actually doing more typing by hacking around than I would have been if I'd used the actual typewriter.