[GreenKeys] Teletype Highspeed (>100 wpm) Equipment Question

[Jim Haynes]

On Sun, 2 Sep 2012, Don Robert House wrote:

> The Type 4 was a really neat system.  I wa lucky enough to be one of

I considered it more of a kluge.  I guess backspacing and re-reading the
tape is not bad, but punching rubouts is awful.  Teletype should have
had a small core or disk memory that could hold the block and be sure
it was good before it was punched.

Then another thing I didn't think of at the time, but some customers
might want to send binary data, in which rubout is a legitimate data
character.  IBM had a solution for this, though I wasn't aware of it
at the time.

The solution is to take some arbitrary character and call it DLE for
Data Link Escape.  If DLE occurs in the data stream then you send
DLE DLE and the receiver discards one of them.  DLE followed by any
other single character is a control character and not part of the
data.