To help train electrical engineers in digital electronics Digital Equipment Corporation (DEC) produced a digital logic trainer together with a training course. It allowed students to connect up various configurations of basic logic gates following a workbook to get a hands on idea of what it was all about.

DEC H-500 Digital Logic Trainer

There was a 110V version (H-500) and a 240V version (H-500-A), but all the logic ran on 5V. It came with a Computer Lab workbook (item B-350) and an assortment of 107 patch cords of assorted lengths from 2.75“ to 24.75” (item “916”). There was also a Computer Lab Teaching Wall Poster (24“ x 36”).

The logic gates were provided by 12 TTL logic chips: 7473, 7400, 7420, 7450, 7400, 7473, 7473, 7410, 7420, 7450, 7410, 7473. The chips are mounted on the under side of a PCB (item H500 PATCHCORD PANEL5004577 5404576B). There is a separate PCB containing the input switches, output lights, oscillator, and power supply (BEWARE mains voltages are present on this board).

There are 8 rocker switches for providing logic 0 or 1 inputs, and 3 momentary rocker switches to provide pulsed inputs. Additionally there is also a variable resistor control for an oscillator that has 6 selectable clock ranges, 3 “fine” and 3 “coarse”

The patch cords are colour coded according t length:

And have uncommon tappered pins on crimped onto each end:

• H-500 Computer Lab Workbook
• H-500 Computer Lab Workbook copy 2
• H500 Computer Lab Teachers Guide

• Some Thoughts from the Author of workbook
• DEC H-500 Computer Lab Reproduction
  • Notes from John Hughes about Computer Lab
• Vince Slyngstad's DEC "Computer Lab" page

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