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Text File | 1992-01-01 | 9KB | 228 lines

Originally Displayed By P-80 Systems Teletype and the Baudot Code by THE RESEARCHER TTY and TDD sent over phone lines uses 1800 Hz for space and 1400 Hz for mark. By comparison, your 300 baud modem uses these frequencies: Originate (space-1070 mark-1270), Answer (space-2025 mark-2225). TTY/TDD is sent at 60 words per minute (45.5 baud). Like RTTY, it uses a five element Baudot code which bears no resemblance to ASCII. I had to build my own demodulator and keyer to check out this information. If you want to check out RTTY, you will need a communications quality short wave receiver and a demodulator. There is some good information on RTTY in chapter 5 of "Specialized Communications Techniques for the Radio Amateur". If you want to explore these areas of telecommunications, you will need more information than I can give you in a short article. The book I mentioned is a good starting point. The following table is a listing of the Baudot code: . TELETYPEWRITER CODE . "*" = MARK "-" = SPACE --------------------------------- . AMERICAN NUMBER TELETYPE . OF CODE ELEMENTS COMMERCIAL SIGNAL !1!2!3!4!5! KEYBOARD ! 1 ! !*!*!-!-!-! ! A ! - ! ! 2 ! !*!-!-!*!*! ! B ! ? ! ! 3 ! !-!*!*!*!-! ! C ! : ! ! 4 ! !*!-!-!*!-! ! D ! $ ! ! 5 ! !*!-!-!-!-! ! E ! 3 ! ! 6 ! !*!-!*!*!-! ! F ! ! ! ! 7 ! !-!*!-!*!*! ! G ! & ! ! 8 ! !-!-!*!-!*! ! H ! # ! ! 9 ! !-!*!*!-!-! ! I ! 8 ! ! 10 ! !*!*!-!*!-! ! J ! ' ! ! 11 ! !*!*!*!*!-! ! K ! ( ! ! 12 ! !-!*!-!-!*! ! L ! ) ! ! 13 ! !-!-!*!*!*! ! M ! . ! ! 14 ! !-!-!*!*!-! ! N ! , ! ! 15 ! !-!-!-!*!*! ! O ! 9 ! ! 16 ! !-!*!*!-!*! ! P ! 0 ! ! 17 ! !*!*!*!-!*! ! Q ! 1 ! ! 18 ! !-!*!-!*!-! ! R ! 4 ! ! 19 ! !*!-!*!-!-! ! S !BELL ! 20 ! !-!-!-!-!*! ! T ! 5 ! ! 21 ! !*!*!*!-!-! ! U ! 7 ! ! 22 ! !-!*!*!*!*! ! V ! ; ! ! 23 ! !*!*!-!-!*! ! W ! 2 ! ! 24 ! !*!-!*!*!*! ! X ! / ! ! 25 ! !*!-!*!-!*! ! Y ! 6 ! ! 26 ! !*!-!-!-!*! ! Z ! " ! ! 27 ! !-!-!-!*!-! !CAR/RET! ! 28 ! !-!*!-!-!-! LINE FEED ! 29 ! !*!*!*!*!*! !LETTERS! ! 30 ! !*!*!-!*!*! !FIGURES! ! 31 ! !-!-!*!-!-! ! SPACE ! ! 32 ! !-!-!-!-!-! ! BLANK ! With only five elements to work with, the maximum number of combinations is 32. To expand the number of characters which can be sent, two of the combinations are devoted to special signals called "letters" and "figures". When a "letters" signal is sent, the receiving equipment knows that the characters which follow are to be interpreted as letters. If a "figures" signal is sent, it means the characters which follow are figures (numbers and puntuation marks). For example, the code for "H" and "#" are the same. Which character is printed is determined by wether it was preceded by a "letters" or "figures" code. I was recently asked by a young hacker to post the EBCDIC character code. Since I am posting telecommunications codes this seems like a good place to include it. If your terminal program includes translation tables, you can use these codes to communicate with computers that use this system. To give credit where credit is due, I want to point out that this bit of nonsequiter confusion was created by IBM. --------------------------- ! The EBCDIC Character Code ! ! ------------------------- ! ! Control Codes ! ! ------- ----- ! ! Dec Hex EBCDEC ! ! --- --- ----- ! ! 0 00 NUL ! ! 1 01 SOH ! ! 2 02 STX ! ! 3 03 ETX ! ! 4 04 PF ! ! 5 05 HT ! ! 6 06 LC ! ! 7 07 DEL ! ! 10 0A SMM ! ! 11 0B VT ! ! 12 0C FF ! ! 13 0D CR ! ! 14 0E SO ! ! 15 0F SI ! ! 16 10 DLE ! ! 17 11 DC1 ! ! 18 12 DC2 ! ! 19 13 TM ! ! 20 14 RES ! ! 21 15 NL ! ! 22 16 BS ! ! 23 17 IL ! ! 24 18 CAN ! ! 25 19 EM ! ! 26 1A CC ! ! 27 1B CU1 ! ! 28 1C IFS ! ! 29 1D IGS ! ! 30 1E IRS ! ! 31 1F IUS ! ! 32 20 DS ! ! 33 21 SOS ! ! 34 22 FS ! ! 36 24 BYP ! ! 37 25 LF ! ! 38 26 ETB ! ! 39 27 ESC ! ! 42 2A SM ! ! 43 2B CU2 ! ! 45 2D ENQ ! ! 46 2E ACK ! ! 47 2F BEL ! ! 50 32 SYN ! ! 52 34 PN ! ! 53 35 RS ! ! 54 36 UC ! ! 55 37 EOT ! ! 59 3B CU3 ! ! 60 3C DC4 ! ! 61 3D NAK ! ! 63 3F SUB ! ! ! ! -------------- ! ! 64 40 SPACE ! ! --------------- ! ! ! ! PUNCUATION & SYMBOLS ! ! -------------------- ! ! Dec Hex EBCDIC ! ! --- --- ------ ! ! 76 4C < ! ! 77 4D ( ! ! 78 4E + ! ! 80 50 & ! ! 90 5A ! ! ! 91 5B $ ! ! 92 5C * ! ! 93 5D ) ! ! 94 5E ; ! ! 96 60 - ! ! 97 61 / ! ! 107 6B , ! ! 108 6C % ! ! 110 6E > ! ! 111 6F ? ! ! 122 7A : ! ! 123 7B # ! ! 124 7C @ ! ! 125 7D ' ! ! 126 7E = ! ! 127 7F " ! ! ! ! Lower Case Letters ! ! ----- ---- ------- ! ! Dec Hex EBCDIC ! ! --- --- ------ ! ! 129 81 a ! ! 130 82 b ! ! 131 83 c ! ! 132 84 d ! ! 133 85 e ! ! 134 86 f ! ! 135 87 g ! ! 136 88 h ! ! 137 89 i ! ! 145 91 j ! ! 146 92 k ! ! 147 93 l ! ! 148 94 m ! ! 149 95 n ! ! 150 96 o ! ! 151 97 p ! ! 152 98 q ! ! 153 99 r ! ! 162 A2 s ! ! 163 A3 t ! ! 164 A4 u ! ! 165 A5 v ! ! 166 A6 w ! ! 167 A7 x ! ! 168 A8 y ! ! 169 A9 z ! ! ! ! Upper Case Letters ! ! ----- ---- ------- ! ! Dec Hex EBCDIC ! ! --- --- ------ ! ! 193 C1 A ! ! 194 C2 B ! ! 195 C3 C ! ! 196 C4 D ! ! 197 C5 E ! ! 198 C6 F ! ! 199 C7 G ! ! 200 C8 H ! ! 201 C9 I ! ! 209 D1 J ! ! 210 D2 K ! ! 211 D3 L ! ! 212 D4 M ! ! 213 D5 N ! ! 214 D6 O ! ! 215 D7 P ! ! 216 D8 Q ! ! 217 D9 R ! ! 226 E2 S ! ! 227 E3 T ! ! 228 E4 U ! ! 229 E5 V ! ! 230 E6 W ! ! 231 E7 X ! ! 232 E8 Y ! ! 233 E9 Z ! ! ! ! Numbers ! ! ------- ! ! Dec Hex EBCDIC ! ! --- --- ------ ! ! 240 F0 0 ! ! 241 F1 1 ! ! 242 F2 2 ! ! 243 F3 3 ! ! 244 F4 4 ! ! 245 F5 5 ! ! 246 F6 6 ! ! 247 F7 7 ! ! 248 F8 8 ! ! 249 F9 9 ! --------------------------- You may have noticed that there are irreqular skips in the numbers above. Unlike ASCII, this code follows no logical sequence. DOWNLODED FROM AND ORIGINALY DISPLAYED ON P-80 SYSTEMS