[GreenKeys] An interesting little patent

[jhaynes@alumni.uark.edu]

Apparently a Model 20 printer was not always available when there was a
need to monitor 6-level Teletypesetter traffic.  Patent 2,750,446
provides for an electronic timer that passes the start pulse and the
first five information pulses and then forces the 6th pulse marking.
This allows a 5-unit printer to monitor, somewhat, a 6-level transmission
since the character codes are about the same in the alphabetic subset.

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jhaynes at alumni dot uark dot edu