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A Polygraph is a duplicating device that produces a copy of a piece of writing simultaneously with the creation of the original, using pens and ink. Patented by John Isaac Hawkins on May 17, 1803, it was most famously used by the third U.S. president, Thomas Jefferson , who acquired his first polygraph in 1804 and later suggested improvements ...
Using letter copying presses, copies could be made up to twenty-four hours after a letter was written, though copies made within a few hours were best. A copying clerk would begin by counting the number of master letters to be written during the next few hours and by preparing the copying book. Suppose the clerk wanted to copy 20 one-page letters.
Baudot developed his first multiplexed telegraph in 1872 [3] [4] and patented it in 1874. [4] [5] In 1876, he changed from a six-bit code to a five-bit code, [4] as suggested by Carl Friedrich Gauss and Wilhelm Weber in 1834, [3] [6] with equal on and off intervals, which allowed for transmission of the Roman alphabet, and included punctuation and control signals.
The tape was placed into a second specially adapted Flexowriter which had two paper tape reading heads; one would read the text while the other controlled the spacing of the print. Spacing codes were stored in relays inside the machine as a line of text progressed.
The tape punch is the unit directly behind the reader. As it exits the machine, the tape passes under a triangular lip that allows the tape to be easily torn by lifting against the sharp edge of the lip. As a cost-saving measure, the optional paper tape mechanisms were dependent on the keyboard and page printer mechanisms.
A Model 20 Teletype machine with a paper tape punch ("reperforator") was installed at subscriber newspaper sites. Originally these machines would simply punch paper tapes and these tapes could be read by a tape reader attached to a "Teletypesetter operating unit" installed on a Linotype machine. The "operating unit" was essentially a tape ...
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A tape transport with an 8-photocell reading mechanism. A six character FIFO shift register. Twelve thyratron ring stores that simulated the Lorenz machine generating a bit-stream for each wheel. Panels of switches for specifying the program and the "set total". A set of functional units that performed Boolean operations.