A machine that punches the sprocket hole can work with pre-punched tape for one or a few cycles, but long-term it will punch an elongated hole and drift out of registration. CTI warns about it in the manual for the 173A “Tape-Ard” I have. (By the way the 173A uses the same Friden engine that IBM OEMed for the 1620’s 1624 punch.)
Some readers backspace but only as a side effect. For example the Remex stepper motor based machines. In high speed mode they stop one space past the target then backspace. Dave Wise > On Jun 27, 2025, at 9:34 AM, Tony Duell via cctalk <cctalk@classiccmp.org> > wrote: > > On Fri, Jun 27, 2025 at 5:09 PM Frank Leonhardt via cctalk > <cctalk@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 > > The Creed 444 scanned manual I have says 'ITT Creed' on it (and the > address is given as Brighton, not Croydon). I think ITT owned Creed at > that pont > > The Creed 444 can also backspace the punch (and will use unpunched tape). > > >> 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. > > Yes, the main use of this facility was to immediately correct a typo > by backspacing the tape and overpunching the incorrect character with > all holes. You didn't need to rewind the tape if you only have 1/10" > of it to bother about. > > -tony
