weird find: papertape "patch" puncher

There have been several designs for homebrew readers, the schematic of one is in the back of the S100 handbook. The unidentified chips in that schemaitc are obviously 555 timers, used as schmitt triggers (!). The only difficult thing to make is the photodiode array for the read head. I wonder if you could use plastic fibre-optic cable to lead the light from a row of holes to some normal-size photodetectors mounted on a PCB in a convenient arrangement. It would be easier than finding some photodetectors that you could mount on 0.1" centres. Making a punch is a lot harder! If you want my recomendations as to units to look out for (assuming you have a choice). Punches : Facit 4070. Easily the top of the list. It's easy to keep going, mechnicallly simple, and has a simple interface (close to Centronics, normally). 'Only' 75 cps, though. Teletype BRPE. OK, it's fast (110cps), but a pain to interface. Not hard to keep running, though. Other Data Dynamics units seem to often have interfaces close to the BRPE, but are slower. Can be useable The GNT34 isn't bad (and is tiny), but you really want to get one with electronics (e.g. as part of the Trend Paper Tape Station). Reders. If given the choice, get a Trend HSR500 (500cps) or UDR350/UDR700. These are quite small, have built-in electronics, and go on for ever. It's almost impossible not to set one up correctly. I _love_ these units. UDRs and HSR500Ps have a builit-in mains PSU, the HSR500 needs mains (for the motor), +5V, and IIRC +24V. Not impossible to power. The other advantage of these units is that they're entirely optical (even the sprocket track) and have a capstan/pinsh roller tape feed. There are therefore very kind to the tapes Other, smaller, optical readers often have optical detection for the data holes only, with a sprocket wheel driven by a stepper motor to feed the tape. Typcially limited to 50cps maximum (most are 30cps), they're useable, but not as kind to the tapes. Facit made a thing which looks like a modified 4070 punch with such a reader built into the front cover (and quite complex electronics inside). Useable, but... Avoild totally mechnanical readers unless you like repairing tapes and correcting read errors. The Teletype ASR33 is fun, but I wouldn't want to use one seriously! -tony