. The Bell System technical journal . gative, currentor no current, or either of two values of current, and the permutationsprovided are 2^ or 32. These are sufficient for the 26 letters of thealphabet, a space, carriage return and paper feed signals as well ascase shifting signals to bring another set of characters into action so asto include numerals and punctuation marks. A chart of this code asused in Teletypewriter P^xchange Service (TWX), is shown below. FIGURESLETTERS A 58 B 1e C $D 3 E 1 4 F &G Q. o1-ul H e 1 J 1 2K 34 L M 78 N 9O 0 1Q 4R _] UJCD S 5 T 7U 38 V 2W /X 6Y Z QUJUJ u. UJ z-
. The Bell System technical journal . gative, currentor no current, or either of two values of current, and the permutationsprovided are 2^ or 32. These are sufficient for the 26 letters of thealphabet, a space, carriage return and paper feed signals as well ascase shifting signals to bring another set of characters into action so asto include numerals and punctuation marks. A chart of this code asused in Teletypewriter P^xchange Service (TWX), is shown below. FIGURESLETTERS A 58 B 1e C $D 3 E 1 4 F &G Q. o1-ul H e 1 J 1 2K 34 L M 78 N 9O 0 1Q 4R _] UJCD S 5 T 7U 38 V 2W /X 6Y Z QUJUJ u. UJ z-J UJ u UJ a: cr< tr UJUJ _i 10 UJ ceu. z< PULSE 1 • • • • • • • • • • •••• •• PULSE 2 • • ••••• • • • ••• • •• PULSE 3 • ••••••• • ••••• •• PULSE 4 • • • • • • PULSE S • • • • • • • • • ••••• •• Fig. 1—Chart of five-unit TWX keyboard used for sending this code is shown Fig. 2—Chart of TWX keyboard. It will be noted that this keyboard is similar to the ordinary type-writer keyboard except that there are only three rows of keys insteadof four as in the typewriter. In the typewriter keyboard, the lowerthree rows of keys are used ordinarily for small letters but when a shift 622 BELL SYSTEM TECHNICAL JOURNAL key is also operated they type the corresponding capital letters. Thefourth or top row of keys carries the numerals and certain punctuationmarks. The teletypewriter types capital letters but not small lettersso that by using a shift or Figures key the upper case position of theletter keys is available for the usual punctuation marks and only three rows of keys are required on the teletypewriter key-board. The operation of the Figures key sends a signal causing thereceiving machine to shift to upper case so that numerals and punctua-tion marks will be printed until a Letters or Space signal is sent wh
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
