4 ms·

I'm really loving following this and I admire the tenacity this must take. For example... Screen brightness too low? Okay, just whip out some ancient circuit d

by epberry 10y ago

I'm really loving following this and I admire the tenacity this must take. For example... Screen brightness too low? Okay, just whip out some ancient circuit diagrams, trace them to find the capacitor at fault, find that capacitor on the board, desolder it, test it, find that it's faulty, resolder a new one. Well that helped but it's not much better sigh. Now examine the switch, CRT tube, etc. And here I've been known to throw in the towel when having 'this' issues in JS.

Animats 10y ago
I do that kind of thing for antique Teletype machines.[1] The discouraging projects are when you get all the way to a working machine and the typing quality is still too bad to be usable. That machine had been dropped at some point. I could do more work on it, but I could get a better one on eBay.[2] [1] http://brassgoggles.co.uk/forum/index.php/topic,43672.0.html http://brassgoggles.co.uk/forum/index.php/topic,43672.0.html [2] http://www.ebay.com/itm/272286062507 http://www.ebay.com/itm/272286062507
- userbinator 10y ago
  Teletypes are interesting because they're basically mechanical UARTs. Watching the mechanisms in them operate still fascinates me.
  - dghughes 10y ago
    You may enjoy Bill Hammack's video "IBM Selectric Typewriter & its digital to analogue converter" https://www.youtube.com/watch?v=bRCNenhcvpw https://www.youtube.com/watch?v=bRCNenhcvpw
    - Animats 10y ago
      The IBM Selectric is a magnificent piece of engineering, and close to being the last complex piece of mass-manufactured mechanical logic . The only electrical part is a motor. But it's not the ancestor of the computer printer. The Selectric's main ancestor is the Blickensderfer_typewriter [1], from 1892. This used a curved type element rather than a typeball, but had a similar method of turning key presses into typing element positions. As with the Selectric, the font could easily be changed. There was a proportional-spacing successor to the Blickensderfer, the Vari-Typer, and IBM imitated that, too, with the IBM Selectric Composer. The Selectric had a moving print head rather than moving paper, with cables on moving idlers used to transmit position to the print head. That mechanism is from the Teletype Model 28/35, from the early 1950s. Moving the print head rather than the paper was a Teletype concept - it worked much better with roll paper, and the machine was narrower. The Selectric mechanism was not designed for electrical inputs and outputs. The add-on mechanism for that was an afterthought, and kind of a hack. The unit had to be built into a table, and the mechanism for the keyboard extended below the tabletop. IBM and Remington had previously built typewriters with electrical I/O, and those were used with some early mainframe computers. Many computers, before and after the Selectric, used Teletype machines as I/O devices. That lasted until daisy-wheel printers and cheap CRT terminals were invented. (Mechanical line printers have a completely separate history. They descend from the Potter Flying Typewriter.[2]) [1] https://en.wikipedia.org/wiki/Blickensderfer_typewriter https://en.wikipedia.org/wiki/Blickensderfer_typewriter [2] https://www.computer.org/csdl/proceedings/afips/1952/5041/00/50410106.pdf https://www.computer.org/csdl/proceedings/afips/1952/5041/00...
  - gumby 10y ago
    They are a glimpse into an earlier age in more ways than one. At that time industrial processes were not as specialized as today and could easily be repurposed. For example in the 1940s IBM's factories (which had been making mechanical tabulators and the like) converted to making guns, bombsights, engine parts and the like. Can you imagine one of Intel's multibillion dollar fabs making anything but single process chips? The whole world isn't quite like that yet; a few years ago I visited a factory in India that made portable generators. Aluminium ingots and copper wire came in one end and generators came out the other. None of the labor was automated. They could have, with some effort, changed products.
- tjl 10y ago
  I repaired a few TVs back in the 80s with my father. He worked as an electrical technician so he'd had all the equipment so when one of our TVs died, he'd open it up, find the fault, and fix it. I had smaller hands so I'd be the one who would actually use the multimeter to check the voltage drop across various components. By the time the 90s rolled around there were a lot more custom chips so we haven't done it since then.
digi_owl 10y ago
Its what you can do when you: A. have the schematics. B. its not just a jumbled mass of ICs.

by epberry 10y ago

Animats 10y ago

I do that kind of thing for antique Teletype machines.[1] The discouraging projects are when you get all the way to a working machine and the typing quality is still too bad to be usable. That machine had been dropped at some point. I could do more work on it, but I could get a better one on eBay.[2] [1] http://brassgoggles.co.uk/forum/index.php/topic,43672.0.html http://brassgoggles.co.uk/forum/index.php/topic,43672.0.html [2] http://www.ebay.com/itm/272286062507 http://www.ebay.com/itm/272286062507

userbinator 10y ago
Teletypes are interesting because they're basically mechanical UARTs. Watching the mechanisms in them operate still fascinates me.
- dghughes 10y ago
  You may enjoy Bill Hammack's video "IBM Selectric Typewriter & its digital to analogue converter" https://www.youtube.com/watch?v=bRCNenhcvpw https://www.youtube.com/watch?v=bRCNenhcvpw
  - Animats 10y ago
    The IBM Selectric is a magnificent piece of engineering, and close to being the last complex piece of mass-manufactured mechanical logic . The only electrical part is a motor. But it's not the ancestor of the computer printer. The Selectric's main ancestor is the Blickensderfer_typewriter [1], from 1892. This used a curved type element rather than a typeball, but had a similar method of turning key presses into typing element positions. As with the Selectric, the font could easily be changed. There was a proportional-spacing successor to the Blickensderfer, the Vari-Typer, and IBM imitated that, too, with the IBM Selectric Composer. The Selectric had a moving print head rather than moving paper, with cables on moving idlers used to transmit position to the print head. That mechanism is from the Teletype Model 28/35, from the early 1950s. Moving the print head rather than the paper was a Teletype concept - it worked much better with roll paper, and the machine was narrower. The Selectric mechanism was not designed for electrical inputs and outputs. The add-on mechanism for that was an afterthought, and kind of a hack. The unit had to be built into a table, and the mechanism for the keyboard extended below the tabletop. IBM and Remington had previously built typewriters with electrical I/O, and those were used with some early mainframe computers. Many computers, before and after the Selectric, used Teletype machines as I/O devices. That lasted until daisy-wheel printers and cheap CRT terminals were invented. (Mechanical line printers have a completely separate history. They descend from the Potter Flying Typewriter.[2]) [1] https://en.wikipedia.org/wiki/Blickensderfer_typewriter https://en.wikipedia.org/wiki/Blickensderfer_typewriter [2] https://www.computer.org/csdl/proceedings/afips/1952/5041/00/50410106.pdf https://www.computer.org/csdl/proceedings/afips/1952/5041/00...
- gumby 10y ago
  They are a glimpse into an earlier age in more ways than one. At that time industrial processes were not as specialized as today and could easily be repurposed. For example in the 1940s IBM's factories (which had been making mechanical tabulators and the like) converted to making guns, bombsights, engine parts and the like. Can you imagine one of Intel's multibillion dollar fabs making anything but single process chips? The whole world isn't quite like that yet; a few years ago I visited a factory in India that made portable generators. Aluminium ingots and copper wire came in one end and generators came out the other. None of the labor was automated. They could have, with some effort, changed products.
tjl 10y ago
I repaired a few TVs back in the 80s with my father. He worked as an electrical technician so he'd had all the equipment so when one of our TVs died, he'd open it up, find the fault, and fix it. I had smaller hands so I'd be the one who would actually use the multimeter to check the voltage drop across various components. By the time the 90s rolled around there were a lot more custom chips so we haven't done it since then.

digi_owl 10y ago

Its what you can do when you: A. have the schematics. B. its not just a jumbled mass of ICs.