The Colossus Rebuild Project by Tony Sale

Colossus Reborn

The Logic Waveforms

The oscilloscope shows parts of two inputs into the logic circuits.

The top trace is from the DeltaK5 stream from the Thyratron K5 ring and the bottom trace is from DeltaZ5 from track 5 on the paper tape.

The paper tape being run is a test tape with pure K streams punched onto it. This is used to test that Colossus is working correctly.

The start point for the K5 ring has been set to exactly the same point as that used to produce the Paper Tape. Thus the double delta algorithm gives "true" for every character on the Tape and the counters thus register a count equal to the total number of characters on the Tape. In this case just over 7,000.

This page was originally created by the late Tony Sale, the original curator of the Bletchley Park Museum, and Secretary of the Bletchley Park Heritage Society.