Mysterious Adder From 1960s Bendix G-20


[David Lovett] aka Usagi Electric powered is having a dive into nevertheless a further outdated personal computer style and design, this a single from the early 1960s. He just lately acquired 8 thriller circuit boards on-mortgage for the intent of reverse engineering them. It turns out these arrived from an aged mainframe termed the Bendix G-20, a successor to the 1965 G-15 vacuum tube model. The cards are:

  • Whole Adder
  • AND Gate
  • OR Gate
  • Emitter Follower
  • Flip Flop
  • Quad Inverting Amplifier
  • DLO Amplifier
  • Gated CPA

Most of these are quite straightforward to figure out, but he ran into some problems trying to realize the whole adder board. The 1st problem is there is some uncertainty surrounding the logic degree voltages. This procedure makes use of adverse voltages, with -3.5 V symbolizing a logic 1 … or is it a logic ? And even taking into account this ambiguity, [David] is having a tricky time deciphering how the adder operates. It works by using a bunch of diodes to carry out a logic lookup table of an adder — besides he is not ready to make it match any recognized addition plan. [David] has called out to the group for help on this one particular, and if you have any suggestions how this adder will work, visit his wiki linked earlier mentioned for much more data and give him shout.

We really don’t know how [David] squeezes in the time for these aspect tasks, when he is so busy on the Centurion mini-laptop restoration and the monstrous one-bit vacuum tube computer he is constructing.


Supply website link

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