27 Jun
2025
27 Jun
'25
11:45 a.m.
On 27/06/2025 15:58, Tony Duell via cctalk wrote:
On Fri, Jun 27, 2025 at 3:49 PM Frank Leonhardt via
cctalk
<cctalk(a)classiccmp.org> wrote:
Thanks - I wasn't sure. I've actually got a few Teletype 32 and 33s in
my shed but I'm too scared to turn them on after 40 years to check. When
I was coding they were earlier Creed models (mostly). It think one was
an Olivetti, which had style, and an ITT branded 444 that looked like it
was from the 21st Century (as I imagined imagined, incorrectly, what the
21st would look like at the time time). I stopped using them even as a
printer when the FX-80 came out :-) (Alas, I only kept the Teletype
Corporation ones, which I kept to scavenge parts).
I seem to recall backed up tape forming a loop rather than rewinding
onto the spool.
My memory may not be reliable, but I certainly
remember some
teleprinters could backspace a tape if you made a mistake, so I guess
they'd have had to tolerate pre-sprocketed tape. I just used them, so I
hadn't thought how it worked before now. They must have wound back
through the punch accurately so a character space could be punched a
second time. I don't remember being a special punch mechanism just for
DEL, but perhaps there was?
The Teletype model 33ASR can backspace the punch for overpunching a character.
In such machines the tape is fed by a sprocket wheel, the teeth of
which engage in the feed holes of the tape. This is positioned after
the punch die assembly. So such a punch needs a bit of help to start
it off on a new reel of unpunched tape but once it has started
punching holes properly it will carry on.
It could use tape with pre-punched feed holes, but equally it can use
unpunched tape.