Interesting that some readers didn't require the sprocket hole. Whilst I can appreciate that they didn't mechanically drive on it, I assumed they'd use it as a clock signal to sample the data levels. Even that could be avoided, but then a nul would be indistinguishable from the space between punch positions.
Did they make nul an illegal character, or determine it using a flywheel sync ? I appreciate there were out-of-band ASCII characters such as EOT but weren't there binary format tapes too ? On Fri, Jun 27, 2025 at 11:29 AM Frank Leonhardt via cctalk <[email protected]> wrote: > > On 24/06/2025 20:16, Wayne S wrote: > > On Jun 24, 2025, at 12:10, Tony Duell <[email protected]> wrote: > >> On Tue, Jun 24, 2025 at 8:04 PM Wayne S via cctalk > >> <[email protected]> wrote: > >>> There’s really a disconnect on between reading and punching paper tape. > >>> For making blank tape that can be used in a punch, you can cut a roll of > >>> something down to a proper width, but the paper has to be thicker than > >>> cashiers paper. The real trick is that the paper has to be perforated in > >>> the middle before use. That’s how it’s “dragged” thru the punch/reader. I > >>> haven’t seen anyone mention how to do that. > >>> > >>> If you can manage to do that, then you could also oil the paper and use > >>> it on a punch. > >> Every paper tape punch (Teletype, Friden, DEC, Facit, Data > >> Dynamics...) I have punches the sprocket holes along with the data > >> holes. Some need a bit of help (pull the tape by hand) to get started > >> on a new roll of tape, but once it starts punching properly it will > >> continue to do so until the roll runs out. > >> > >> -tony > > Interesting. > > All the ones i used, including some teletypes, needed pre-punched tape, > > ostensibly to ensure proper alignment. We used to buy pallets of prepunched > > tape. > > > > Sent from my iPhone > > My experience is the same as Waynes - I've never seen a punch that > didn't punch the sprocket hole and I've never seen one that required > one. Perhaps it's an American thing (reminder: I'm in the UK, where > Paper Tape was king). This would have been everything Creed, Elliott and > later Teletype (e.g. ASR33) and probably a few I can't remember. I've > never even seen pre-punched tape. > > I'm suspect some optical readers didn't require it as the tape was > advanced using a pinch roller until a non-null punch was received. > > Regards, Frank. >
