[GreenKeys] Chadless vs. Full perforation

[Jim Haynes]

I believe the main idea of chadless was to make it easy for a typing
reperforator to print on it.  A secondary benefit is not having to
dispose of the chads, since they are all "hanging" chads by election
definitions.

I remember a demonstration for an old FAA guy.  He complained about
the chadless tape being hard to read, since he was accustomed to reading
the hole patterns, having memorized the code.  No doubt he needed reading
glasses.

I believe chadless tape was exclusive to Teletype.  Western Union and
Kleinschmidt liked to use wider tape and print the characters in the
margin.  Later on Teletype developed a typing reperforator that printed
between the feed holes.

The main use of printed & perforated tape is in torn tape switching
installations, where the operator can read the message destination from
the tape without having to memorize the code.  What makes memorizing the
code a little hard is that you have to memorize both LTRS and FIGS cases
and then when reading the tape you have to know which case you are in.