[GreenKeys] 5-bit? 6-Bit? What do you suppose we have here?

[Jim Haynes]

What we have here is paper tape Morse, which uses a tape with two holes
plus the feed hole.  The keyboard perforator was designed by Kleinschmidt
and remained in the Teletype catalog through the early 1940s.

Several applications:\

For undersea cables they used a 3-level code with one polarity for dot and
the other for dash and no current in between.  This speeded up things by
making dash have the same time duration as dot, which was important on
cables where the bandwidth is so severely limited.  Reception was by ink
trace on paper tape, then translated to hard copy by operators at 
typewriters.

For radio they used conventional dot-dash Morse, but sometimes transmitted
at very high speeds, up to 500 wpm.  Reception likewise by ink trace on
paper tape and transcribed to hard copy by operators.

For code practice, sent at normal speeds as conventional Morse.

jhhaynes at earthlink dot net