24 Jun
2025
24 Jun
'25
5:14 p.m.
Burroughs used both type 1 and 2; the issue with the 'high speed' optical
readers was not so much internal but external, when the tape would
accidentally get tangled and torn. Mylar was just so much more forgiving,
even after a hundred or more reads, by which time the normally fairly stiff
mylar would have become as soft as a good quality toilet paper.
On Tue, Jun 24, 2025 at 3:20 PM Tony Duell <ard.p850ug1(a)gmail.com> wrote:
On Tue, Jun 24, 2025 at 3:49 PM Mike Stein via
cctalk
<cctalk(a)classiccmp.org> wrote:
Mylar tape was indeed used in hostile environments but also elsewhere
where
it would be read many times, for loading
programs, firmware or fixed
data;
the much cheaper and more fragile paper tape
would usually be used for
transferring or archiving data which would either be stored and archived
or
read once and discarded when an updated tape was
made.
It depends to some extent how 'kind' your reader is to the tape.
There are basically 3 types of readers, least kind first :
1) Feed using the sprocket holes on a toothed sprocket, sense the data
holes with mechanical feelers (Creed call them 'Peckers' in their
service manuals). Often found as part of ASR teleprinters.
2) Feed using the sprocket holes on a toothed sprocket but use a
non-contact method to sense the data holes, Normally optical but there
was at least one capacitive reader. An example is the DEC PC04 or
PC05. There are many others.
3) Feed the tape between a smooth capstan and pinch roller. Sense the
sprocket and data holes using a non-contact method. HP2748, some
Elliot readers, the excellent Trend UDR700 or HSR500.etc.
A paper tape may be damaged after a few passes through a mechanical
reader but will be good for hundreds of reads on one of type {3}.
-tony