[GreenKeys] TTY Era in AP

[Betty Clark]

The software used for the Gazette demonstration was furnished by the AP
Bureau in Kansas City. They can be reached at Darin Henderson@ap.org,
who is one of the technicians there.

The dual-headed Model 28ASR TD was used with a one-time tape where one
tape was the actual message; the other tape was a random-cyphered tape.
The tapes were then combined to produce a cypher-tape. On the other end
of the circuit, the cypher tape was combined with a copy of the same
random tape, which produced the original message. The tapes were
combined by making the likes (mark + mark or space + space) equals
marks. The unlikes (space + marks) combined to make spaces. The random
tapes were one-time tapes that were discarded after use.

Wes