Speaking of news teletype sound effect
John J. Francini
francini@mac.com
Thu Dec 8 00:16:47 EST 2005
At 20:25 -0500 12/7/05, rogerkirk wrote:
>SteveOrdinetz wrote:
>>Didn't those run at 56 Baud or something equally speedy?
>
>IIRC, it was 110 baud.
Computer teletypes -- that speak 8-bit-per-character ASCII -- ran
(run?) at 110 baud -- 10 characters a second. Each character at that
rate was 11 bits long: 1 start bit, 8 bits of data, and 2 stop bits.
Wire service TTYs spoke a 5-bit code, called Baudot, that ran at 50,
60, or 75 baud. Depended on the service provider. The 5-bit code only
allows for 32 characters. In order to handle both numbers and
letters, two characters were reserved for the special functions SHIFT
IN and SHIFT OUT. On receipt of SHIFT IN, the printer mechanism would
shift from printing letters to printing figures (numbers and special
characters). The printer would revert to letters upon receipt of the
SHIFT OUT character.
Probably a case of Too Much Information, but I've always had a soft
spot for TTYs...
john
--
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John Francini <mailto:francini@mac.com>
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