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I think I've mentioned this before, but I would never use a sprocket-fed mechanical reader on an irreplaceable paper tape. It just takes one little tape jam to rip the sprocket holes apart. The best readers (if you can find one) are pinch roller/capstan fed opticals. It's almost impossible to mangle tape with one of those. Even standing on the tape when one is going at full speed (500 cps+) will generally only snap the tape cleanly, and that's quite easy to splice. I like the Trend units made in the UK. They have the advantage that they have DTL/TTL I/O lines and are thus easy to interface to just about anything. I have a little circuit to link one to a PC printer port, which sends the data back in 2 nybbles on the status lines. The only time I ever _bought_ a teleprinter, it cost me \pounds 1.00 (about $1.50). It was at a radio rally, and the chap didn't want to take it home again. Well, the UAR is mechanical, but the UAT is partially electrical. There's a spinning carbon brush that runs over a PCB to select the data lines from the keyboard/reader in turn. Some of the UK Creeds have a mechanical transmitter as well - one contact and a camshaft to set it to the state of each bit in turn. One of the craziest readers I have is a Creed. The tape is sprocket-fed using a sprocket that turns continuously. A camshaft lifts the read pins (peckers (!)) in turn to sample each track, and sets the output contact to the appropriate position. The line of peckers is thus on a slant, not at right angles to the tape motion. Mechanical tape readers are fun, and they're fun to repair and demonstrate, but I'd not want to use one as my only reader. -tony

For those interested, I have what appears to be a pretty complete set of ASR33 documentation...5 books...2 photocopied, 3 originals that I'd be willing to trade for something more up my alley...like an S100 card or two (or 5, 10, 20, 50, 100 =)...or something along those lines. (I'll consider all kinds of things. Of course, as soon as I don't have the documentation, that's when I'll find a teletype. :-/ No guts, no glory. =) Anthony Clifton - WireHead Prime wirehead(a)retrocomputing.com http://www.retrocomputing.com http://www.retrocomputing.org

On Tue, 2 Sep 1997 18:11:58 -0800 (PDT) Tim Shoppa <shoppa(a)alph02.triumf.ca> writes: What a coincidence, I am looking through a book - Computer Peripherals That You Can Build by Dr. Gordon W. Wolfe, and there are plans for a electro-optical paper tape reader to replace the ASR-33. It says "Reading a long program in on paper tape can be quite a chore, since the ASR-33 reads only ten characters a second". Then it claims that "Using an optical reader with handshaking on a parallel port, up to 500 characters per second may be read - as fast as you can pull the tape through!" It shows the schematics for building the reader, and a flowchart for the read program. I could probably type in the section, and scan the diagrams if anyone is interested in building their own. For all those people out there with the skills, it's a really interesting book, it even has plans and schematics for a touch response display. I might even try building one of those. It would be a hit at work. I can still look like someone on the cutting edge, getting projects from a 15 year old book. Just let me know if anyone is interested in the plans. I might not be able to get to it tomorrow, but it won't take long, and maybe someone with the knowledge and skills can "mass produce" some for the people in the list that need them. Isaac Davis | Don't throw out that old computer, Atari nut | check out the Classic Computer Rescue List - indavis(a)juno.com | http://www.geocities.com/BourbonStreet/1055/classic.html P.S. I have been busy, and not able to update the list recently, but I hope to catch up by this weekend. Work just will not let up.