And leave us not forget Colossus, reading paper tape at 5000 characters/sec with the sprocket hole providing the strobe pulse. Using photomultiplier tubes in 1944.
Tape speed 30 mph.
From: Harold Hallikainen via GreenKeys <greenkeys@mailman.qth.net> -- Friday, August 28, 2026 3:55 PM
On Fri, August 28, 2026 1:11 pm, David Wade via GreenKeys wrote:
? The feed hole detector was a strobe for the data since the hole is smaller than the data holes and centered on the data.
Lots of high-speed photoelectric paper-tape readers worked that way. I've got an old IOMEC reader that has a capstan and pinch roller to move the tape (very fast, no sprocket anywhere), an electromagnetic brake to stop it (on a dime) and 9 channels of photocells, the sprocket cell serving as strobe. It shows its age because it uses a single incandescent bulb to illuminate all tape channels where a design from after about 1972 would have used one LED per channel.