Do Model 33 ASR's ever show up at hamfests
anymore? Back when I was in
high school, these were the de facto solution for reading and/or
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.
punching 8-level paper tapes. (And you got a keyboard
and printer as part
of the deal...) At that point in time (roughly 12 or 15 years ago, now)
Model 33 ASR's went for US$100-US$150. I remember trading a Sinclair
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.
ZX80 for one and still think it was the best deal I
Unlike the high-speed optical readers, the Model 33 ASR's were purely
mechanical (including the UART, of course...)
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.