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Baudot-Murray code

In digital telegraphy (teleprinter, telex) a 5-bit encoding standard is commonly used to represent a character (letter, number or punctuation mark). Although this code is generally known as the Baudot code, this name is actually wrong. The official name for the latest telegraphy standard is ITA-2 (International Telegraph Alphabet No 2). It was superceeded by ITA-5 (ASCII) in 1963, but is still used by amateurs today. The most common 'Baudot' code is also known as Murray code, or as Baudot-Murray code. The ITA-2 standard is used widely with historical cipher machines.

Normal text consists of over 50 different characters (26 letters, 10 numbers, 10 punctuation marks and some control codes). In the ITA-2 standard, 5 bits are used to represent a character, which means that only 32 different codes can be created (25). As this would not be sufficient for normal text, most codes are used twice (i.e. have two different meanings) and special reserved codes are used to shift between the two code sets, known as Letters (LTRS) and Figures (FIGS).

The table below shows the interpretation of the commonly used ITA-2 standard. Although this code has officially been superceeded by ITA-5, it is still used today on some old telex networks and by Radio Amateurs. Some of the cipher machines described on this website, use 5-bit digital encoding and many of them (if they support the Latin character set) follow the ITA-2 standard.

LTRS-shift is represented by 111·11 (5 holes), so that it can be used to wipe part of a paper tape, without affecting the rest. Normally, a paper tape would start with two LTRS characters, to ensure that the teletype is in Letters-mode. By convention, the holes (bits) in the tape are called channels or tracks and the tape is shown as it would run through the reader away from you.

Cipher machines that use ITA-2
The Siemens T-52 'Geheimschreiber'
Lorenz SZ-40/42 cipher machine
The Siemens T-43 mixer machine
British/Canadion one-time tape cipher machine used during and after WWII
British 5-UCO (BID/30) OTT cipher machine
SIGTOT one-time tape cipher machine (US)
ATCRRM mixer machine used on the Washington-Moscow hotline
British one-time tape cipher machine compatible with Rockex
PTT Colex (predecessor of Ecolex)
Ecolex I, developed by PTT, manufactured by Philips Usfa
Ecolex II, developed by PTT, manufactured by Philips Usfa
Philips Ecolex IV
Siemens Schlüsselgerät D
Siemens M-190 OTT cipher machine, used on the Washington-Moscow hotline
Hagelin TC-52
Hagelin C-446-RT, the OTP (OTT) version of the C-446
OTP/OTT version of the Hagelin CX-52
DUDEK StG-1 (T-352 / T-353) one-time tape cipher machine developed in Poland
OTT cipher machine (mixer) for teletype networks (telex)
Mils Elektronik one-time tape cipher machine, developed in the mid-1970s.
Mils Elektronik one-time tape cipher machine, with key generator
Lorenz Mixer (Mi-544)
SELMA OKA-150, telegraphy cipher machine
TAROLEX key stream generator
Ecolex X (Ecolex 10) online/offline cipher machine
Aroflex UA-8116
RACE (KL-51)
HC-570 CRYPTOMATIC desktop electronic cipher machine
HC-550 CRYPTOMATIC desktop electronic cipher machine
The Siemens T-1285CA (Aroflex) cipher machine
 Teletypewriters (telex machines)

Ltr Letters (A-Z)
Fig Figures (Numbers and punctuation marks)
Ctrl Control characters
Hex Hexadecimal code
Bin 1 Binary, Positions of the holes in the paper tape
# Ltr Fig Hex Bin  
0 NUL 00 000·00 NULL, Nothing (blank tape)
1 E 3 01 000·01  
2 LF 02 000·10 Line Feed (new line)
3 A - 03 000·11  
4 SP 04 001·00 Space
5 S ' 05 001·01  
6 I 8 06 001·10  
7 U 7 07 001·11  
8 CR 08 010·00 Carriage Return
9 D ENC 09 010·01 Enquiry (Who are you?, WRU)
10 R 4 0A 010·10  
11 J BEL 0B 010·11 BELL (ring bell at the other end)
12 N , 0C 011·00  
13 F ! 0D 011·01 Can also be %
14 C : 0E 011·10  
15 K ( 0F 011·11  
16 T 5 10 100·00  
17 Z + 11 100·01  
18 L ) 12 100·10  
19 W 2 13 100·11  
20 H $ 14 101·00 Currency symbol — Can also be £
21 Y 6 15 101·01  
22 P 0 16 101·10  
23 Q 1 17 101·11  
24 O 9 18 110·00  
25 B ? 19 110·01  
26 G & 1A 110·10 Can also be @ 
27 FIGS 1B 110·11 Figures (Shift on)
28 M . 1C 111·00  
29 X / 1D 111·01  
30 V ; 1E 111·10  
31 LTRS 1F 11·111 Letters (Shift off)
Other standards
  1. ECMA, Standard ECMA-10 for Data Interchange on Punched Tape
    2nd Edition. July 1970.

  2. Wikipedia, Punched tape
    Retrieved January 2015.

  3. R&S Manual of Transmission Methods
    4070.0711.02-03. Rohde & Schwarz, München (Germany) 2014.
Further information
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© Crypto Museum. Created: Tuesday 20 January 2015. Last changed: Tuesday, 28 February 2023 - 08:45 CET.
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