Specimens of Binary and Other Codes

1. To translate everyday English into Morse Code, and play it back on audio, we recommend the conversion applet at Southampton University's website.
2. There is a complex and confusing history to the development and naming of telegraph codes of the Baudot type. For example, Hobbs (1999/2002 online) starts by explaining (a) that Emile Baudot's original 1874 telegraph code was actually devised by two other workers, Johann Gauss and Wilhelm Weber, and (b) that it never actually went into production in any case. Systems claiming to use "Baudot" code are therefore using the term generically rather than accurately. The system was eventually standardised as the International Telegraph Alphabet No. 1, but had a number of national variants. In 1901, the New Zealander Donald Murray devised a rival code, which was eventually standardised by the CCITT (the Comité Consultatif International Téléphonique et Télégraphique of the International Telecommunication Union) as the International Telegraph Alphabet No. 2 (although again there were US and European variants). To translate everyday English into ITA2, and print it out on virtual paper tape, we recommend the conversion applet at Ralf Kloth's website. We need say no more here, because we could never compete with the "forensic bitology" of Jennings (1999-2002 online).
3. It is not particularly useful to express any of the teleprinter alphabet variants in binary form, because there are major problems agreeing the order of the significant digits. For example, the Baudot keyboard consisted of two keys operated by the middle and index fingers of the left hand, slightly separated from three more keys to be operated by the index, middle, and ring fingers of the right hand [picture]. Any combination of one, two, three, four, or five keys could be depressed, each indicating a particular character from the alphabet. Skill at keying was acquired during training, much as a guitar player learns to press certain combinations of strings, or a trumpet player learns to depress certain combinations of valves. We have shown the keying combinations in what we feel is the "commonsense" representation, namely as the keyboard operator would view his/her own fingers from above, using < X > to record a key depression, and < · > to record no key depression [this being the shorthand form used by the Bletchley Park cryptanalysts during World War Two - see Part 3]. The Baudot letter "A", for example, is .....

Left middle finger NOT DEPRESSED (interpretable as binary ZERO, but shown as < · >)

Left index finger NOT DEPRESSED (interpretable as binary ZERO, but shown as < · >)

Right index finger DEPRESSED (interpretable as binary ONE, but shown as < X >)

Right middle finger NOT DEPRESSED (interpretable as binary ZERO, but shown as < · >)

Right ring finger NOT DEPRESSED (interpretable as binary ZERO, but shown as < · >)

We therefore show the letter "U" in our "Baudot" column as < · · X · X >. Sources which insist on showing the Baudot codes as binary will often load numeric right from keyboard left, thus reversing the apparent pattern (making "U", for example, 10100 rather than 00101). 

4. ASCII codes such as those shown in this column are used for alphanumeric representation in most modern personal computers. They are the codes you are sending into your computer every time you depress the keys on your keyboard. The bits are either all sent at once, or serially according to the LSB rule (ie. least significant bit first, that is to say, from right to left). For historical reasons, there are both 7-bit and 8-bit versions of the codes, the basic and "extended" alphabets, respectively. Since 2⁷ is 128, the 7-bit alphabet is limited to 128 different characters (including those listed here). Since the computer's CPU is quite happy to calculate in binary, it is safe to show these as binary numbers in the range 0000000 to 1111111, and to then call them by their decimal equivalents (decimal 0 to 127 inclusive) whenever that is less confusing. Since 2⁸ is 256, the 8-bit alphabet can cope with an additional 128 characters, that is to say, 256 different characters in the range 00000000 to 11111111 (decimal 0 to 255 inclusive). The 8-bit characters listed in this column all begin with 0, so could just as easily have been 7-bit codes. The binary number one up from 11111111 would be the 9-bit number 100000000 (decimal 256 - note how all eight low-order bits have "carried"), and cannot therefore exist in a 7- or 8-bit alphabet. To see the complete 7-bit ASCII and 8-bit Extended ASCII alphabets, click here.
5. The numbers shown in this column are the decimal equivalents of the binary codes shown in the column immediately to its left. This alternative notation is often useful because it is easier for decimal-trained humans to remember than the much longer binary strings. For back-to-basics instruction on how to convert decimal notation into binary, we recommend Northwestern University's Music School's website, and for a neat decimal-to-binary conversion applet, click here.

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