[GreenKeys] overprinting

[Jim Haynes]

On Thu, 18 Oct 2012, Richard wrote:

> Can you overprint with a teletype by sending CR (but no LF) or using
> backspace?
> -- 
Ordinarily, yes.  Some machines are equipped with automatic carriage
return and line feed, and on one of those you get a line feed on a
carriage return, which is intended to prevent overprinting.  Especially
on a radio circuit where if you miss a carriage return you get the
next line typed into a black square at the end of the line, and if you
miss a linefeed you get the line printed over the previous line.
So the machine is arranged to automatically CR and LF both before the
carriage gets to the stop at the end of the line.

Then there was the famous K8DKC (Irv Hoff) stuntbox.  Back around 1970
there was an active autostart net in California.  Some people grew tired
of Irv because he was very talkative.  As a practical joke they would
fire up his machine on autostart and then send a long string of LFs to
cause his machine to spew out all its paper.  I don't remember now the
precise details of the stuntbox modification, but it involved adding
the auto-CR-LF feature, and then disabling the normal LF and having CR
cause a LF, but only once until some other characters were received.
So it was considerably harder to make the machine spill all its paper.