3 ms·

One big difference is that it's all in 3D. Electronics is done with off the shelf parts, physical position doesn't usually matter to the millimeter, electricit

One big difference is that it's all in 3D. Electronics is done with off the shelf parts, physical position doesn't usually matter to the millimeter, electricity follows the wire except with RF and high voltage. The other difference is that none of the techniques are familiar to anyone but MEs anymore. Most hackers know software, some of us can do hardware, a few can do light woodworking and 3D printing... but I've never implemented even basic logic in any mechanical way. Plus, they had to do it all WITHOUT CAD. Everything about it is impressive and really cool.

Animats 3y ago
> The other difference is that none of the techniques are familiar to anyone but MEs anymore. There is that. But this thing isn't that bad. All the motion is slow. There are no gyros. The precision requirements are modest. It's only 2 1/2D; it's a vertical component stack. There are no diagonal shafts or long, odd-shaped levers. It's not power-limited to the degree that a clock is. Everything is statically driven; there are no components that depend on inertia, which is appropriate for an aircraft system. It doesn't have wheel and disc integrators, which depend on friction and are touchy. This thing is all gears and cams, which are well-behaved. As the original article points out, it performs a simple computation which is a well defined function of the current inputs. I've seen the ground-based mechanical computers that controlled a Nike missile, and those are similar technology as this but much more complex. I've restored century-old Teletype machines, and those are more complex than this thing. Now, those really did require mechanical genius to design. All the good Teletype machines were designed by two people, Howard Krum and Ed Klienschmidt. It took a long time, decades, to get the core design right, and even Siemens, which built their own variation, did not redesign the core decoding mechanism. William Burroughs designed the first really reliable adding machine mechanism, and Burroughs dominated that market for decades. Burroughs had to design by scribing lines on zinc sheets; paper drawings didn't hold dimensions accurately enough. Ottmar Mergenthaler's Linotype design barely changed over a century, being better than both its predecessors and successors. Those guys were mechanical design geniuses. This Bendix device is a good, workmanlike design, but not in that class.
- eternityforest 3y ago
  The fact that they actually had to worry about the precision of drawings in addition to the actual device is amazing. It's such a foreign concept in the computer age, where you never want any information to be exclusively analog like that, you never want to directly rely on a steady hand, and drawings are just a UI on top of numbers and constraints. I still think the Bendix is a bit outside the difficulty level of most modern tech work, but scribing lines on zinc sheets and decoding what's essentially UART without silicon is just insane. That's an amazing story right there!
  - Animats 3y ago
    > UART without silicon Here's the actual serial data decoder, from when I was restoring a Teletype machine.[1] There's a short essay on mechanical design philosophy over there. > It's such a foreign concept in the computer age, where you never want any information to be exclusively analog like that, you never want to directly rely on a steady hand, and drawings are just a UI on top of numbers and constraints. Which is why AutoCAD was so successful. Engineering departments used to have huge rooms full of people at large drafting tables. Good drafting rooms had north-facing skylights. HP's old headquarters on Page Mill Road has four large buildings like that. [1] https://brassgoggles.net/forum/index.php/topic,43672.0.html https://brassgoggles.net/forum/index.php/topic,43672.0.html
    - eternityforest 3y ago
      That is really cool! I didn't even know that forum existed!

Animats 3y ago

> The other difference is that none of the techniques are familiar to anyone but MEs anymore. There is that. But this thing isn't that bad. All the motion is slow. There are no gyros. The precision requirements are modest. It's only 2 1/2D; it's a vertical component stack. There are no diagonal shafts or long, odd-shaped levers. It's not power-limited to the degree that a clock is. Everything is statically driven; there are no components that depend on inertia, which is appropriate for an aircraft system. It doesn't have wheel and disc integrators, which depend on friction and are touchy. This thing is all gears and cams, which are well-behaved. As the original article points out, it performs a simple computation which is a well defined function of the current inputs. I've seen the ground-based mechanical computers that controlled a Nike missile, and those are similar technology as this but much more complex. I've restored century-old Teletype machines, and those are more complex than this thing. Now, those really did require mechanical genius to design. All the good Teletype machines were designed by two people, Howard Krum and Ed Klienschmidt. It took a long time, decades, to get the core design right, and even Siemens, which built their own variation, did not redesign the core decoding mechanism. William Burroughs designed the first really reliable adding machine mechanism, and Burroughs dominated that market for decades. Burroughs had to design by scribing lines on zinc sheets; paper drawings didn't hold dimensions accurately enough. Ottmar Mergenthaler's Linotype design barely changed over a century, being better than both its predecessors and successors. Those guys were mechanical design geniuses. This Bendix device is a good, workmanlike design, but not in that class.

eternityforest 3y ago
The fact that they actually had to worry about the precision of drawings in addition to the actual device is amazing. It's such a foreign concept in the computer age, where you never want any information to be exclusively analog like that, you never want to directly rely on a steady hand, and drawings are just a UI on top of numbers and constraints. I still think the Bendix is a bit outside the difficulty level of most modern tech work, but scribing lines on zinc sheets and decoding what's essentially UART without silicon is just insane. That's an amazing story right there!
- Animats 3y ago
  > UART without silicon Here's the actual serial data decoder, from when I was restoring a Teletype machine.[1] There's a short essay on mechanical design philosophy over there. > It's such a foreign concept in the computer age, where you never want any information to be exclusively analog like that, you never want to directly rely on a steady hand, and drawings are just a UI on top of numbers and constraints. Which is why AutoCAD was so successful. Engineering departments used to have huge rooms full of people at large drafting tables. Good drafting rooms had north-facing skylights. HP's old headquarters on Page Mill Road has four large buildings like that. [1] https://brassgoggles.net/forum/index.php/topic,43672.0.html https://brassgoggles.net/forum/index.php/topic,43672.0.html
  - eternityforest 3y ago
    That is really cool! I didn't even know that forum existed!