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Tuesday, May 18, 2021

TRACKING WITH CLOSEUPS: Hewlett-Packard AC-4G Vacuum Tube Decade Counter

The use of a 4-2-1-1 binary code instead of 8-4-2-1 binary-coded decimal seems odd until you see the stunningly clever way they use it both to drive the indicator neon bulbs and generate the analogue ramp output without the wheelbarrow full of parts it would take to do the way we do now with integrated circuits.

Posted at May 18, 2021 13:06