3 ms·

Thank you for that link. I took the liberty of re-posting it separately, it is one of the coolest things I've ever seen built. Besides the memory (and that woul

by 0x12 15y ago

Thank you for that link. I took the liberty of re-posting it separately, it is one of the coolest things I've ever seen built. Besides the memory (and that would just add another couple of 10's of thousands of relays for a usable machine) that looks like the shortest direct path between 'man on a beach' and having a working automatic computer with a practical degree of reliability.

JoshTriplett 15y ago
"practical degree of reliability" seems somewhat debatable; it apparently burns out components fairly often when running. IIRC it uses quite a bit more juice than it needs to, which might have something to do with it, so perhaps it could be made more reliable.
- 0x12 15y ago
  Relay contacts tend to spark when they engage each other. You can get rid of most of that sparking by adding diodes but that would be cheating (semiconductors again), to a lesser extent using small neon bulbs across the coils (that will still take them up to 90V though). With 'practical' I meant that you would be able to run programs to completion for for instance numerical problems. Vacuum tube computers suffer from different problems (such as tube filaments burning out) and I really wonder whether a well designed vacuum tube computer would be more or less reliable than a well designed relay based computer. Vacuum tubes got awfully small in their final days but the voltages involved and the heat make me believe that relays would probably be more reliable, but likely also more expensive and much slower.
  - stan_rogers 15y ago
    A capacitor will deal with the sparking -- they've been used (under the name condenser) in conjunction with points and mechanical distributors in internal combustion engines for years. This all presupposes a memory of methods to create reliable electricity, though -- including rectification and filtering, if that memory involves alternators. A purely mechanical representation of computing would probably be more practical in a forced Iron Age reboot of society. A treadmill-powered version of Photoshop would be a bitch, of course, but number crunching (at the level needed for serious societal progress) would come fairly quickly.
    - JoshTriplett 15y ago
      The relay computer does use a capacitor: a huge 1F capacitor.
      - 0x12 15y ago
        That's to stabilize the power supply, not to help with avoiding contact erosion.

by 0x12 15y ago

JoshTriplett 15y ago

"practical degree of reliability" seems somewhat debatable; it apparently burns out components fairly often when running. IIRC it uses quite a bit more juice than it needs to, which might have something to do with it, so perhaps it could be made more reliable.

0x12 15y ago
Relay contacts tend to spark when they engage each other. You can get rid of most of that sparking by adding diodes but that would be cheating (semiconductors again), to a lesser extent using small neon bulbs across the coils (that will still take them up to 90V though). With 'practical' I meant that you would be able to run programs to completion for for instance numerical problems. Vacuum tube computers suffer from different problems (such as tube filaments burning out) and I really wonder whether a well designed vacuum tube computer would be more or less reliable than a well designed relay based computer. Vacuum tubes got awfully small in their final days but the voltages involved and the heat make me believe that relays would probably be more reliable, but likely also more expensive and much slower.
- stan_rogers 15y ago
  A capacitor will deal with the sparking -- they've been used (under the name condenser) in conjunction with points and mechanical distributors in internal combustion engines for years. This all presupposes a memory of methods to create reliable electricity, though -- including rectification and filtering, if that memory involves alternators. A purely mechanical representation of computing would probably be more practical in a forced Iron Age reboot of society. A treadmill-powered version of Photoshop would be a bitch, of course, but number crunching (at the level needed for serious societal progress) would come fairly quickly.
  - JoshTriplett 15y ago
    The relay computer does use a capacitor: a huge 1F capacitor.
    - 0x12 15y ago
      That's to stabilize the power supply, not to help with avoiding contact erosion.