PDP-11's DECcasete

From: Allison J Parent <allisonp_at_world.std.com>
Date: Thu Mar 16 21:13:44 2000

<You rang a bell with the comment about other units using the same
<standard, a TI "Silent 700 ASR" data capture terminal is sitting in my
<storage shed somewhere----neat panel up above the keyboard with lots of
<lights and switches and 2 very fancy looking cassette transports. must
<use those same cassettes.

Same or similar. At one time I was doing cassettes for data storage
(ca 1975-76) and still have my Redactron drive and also MPI plus a few other
scraps.

There were two major schools on the drive, capstan driven (PHI deck) and
reel to reel drive. Obviously one was constant speed tape and the other
without elaborate electronics were constant data rate (more or less).
The tapes themselves were different length, formulations and even front
coatings. Compatable... barely from the same drive.

<> > DEC claimed that you couldn't use regular audio cassettes with the TU6
<> > because they couldn't handle the high tension used by the drive. Sound
<> > it could be hype but you never know. I mean, what's the point of build
<> > peripheral that uses regular audio cassettes, except that it *doesn't*
<> > regular audio cassettes? Worst of both worlds.

True, while they would work for a while eventually they stretch though
some audio tapes were thicker. Also most audiotapes had huge dropout
zones where the recorded level would drop significantly.

Also the saturation recording was nothing like audio recording in how the
head was driven or the read back signal. The closest thing we have now to
the recording technique used is floppies.

Allison
Received on Thu Mar 16 2000 - 21:13:44 GMT