Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!texbell!vector!telecom-gateway From: andyb@coat.com (Andy Behrens) Newsgroups: comp.dcom.telecom Subject: Re: The 'Public Telegraph Office' Message-ID:Date: 3 Oct 89 04:54:24 GMT Sender: news@vector.Dallas.TX.US Reply-To: andyb@coat.com Organization: Burlington Coat Factory Warehouse Lines: 53 Approved: telecom-request@vector.dallas.tx.us X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@vector.dallas.tx.us X-TELECOM-Digest: volume 9, issue 425, message 6 of 6 Dik T. Winter writes: > Here follows the CCITT #2 code table: > > Letters Figures > 0 8 16 24 > +-------------------------------------------------------- > 0 | space LF E A ... > 1 | T L Z W ... > 2 | CR R D J ... > 3 | O G B figures ... > 4 | nil I S U ... > 5 | H P Y Q ... > 6 | N C F K ... > 7 | M V X letters ... At first there seems to be no pattern to the way the letters are assigned, but if you arrange them according to the number of bits that are set in each character, it becomes clear. The most common letters of the English alphabet (ETAIONSHRDL....) and the word separators (space, return, line feed) have the codes with the fewest number of marking bits. Question 1. Does anyone know why this is so? My theory: If the teletype machines are driven with a current-loop interface, this arrangement of codes minimizes the power that needs to be transmitted. Question 2. Why was "Z" grouped with the most common letters? ============ ============ ============ ============ ============ ============ no bits 1 bit 2 bits 3 bits 4 bits 5 bits ============ ============ ============ ============ ============ ============ 00000 blank 10000 E 11000 A 01110 C 11110 K 11111 ltrs 01000 lf 01100 I 10110 F 11101 Q 00100 space 00110 N 01101 P 11011 figs 00010 ret 00011 O 11010 J 10111 X 00001 T 10100 S 10101 Y 01111 V 01010 R 01011 G 00101 H 11100 U 10010 D 11001 W 01001 L 10011 B 10001 Z 00111 M ============ ============ ============ ============ ============ ============ Live justly, love gently, walk humbly. Andy Behrens andyb@coat.com uucp: {harvard,rutgers,decvax}!dartvax!coat!andyb RFD 1, Box 116, East Thetford, Vt. 05043 (802) 649-1258 Burlington Coat, PO Box 729, Lebanon, N.H. 03766 (603) 448-5000