The first question that pops to mind is 'Why aren't the codes sorted alphabetically?' Answer: Because it was originally designed to by typed by hand on a five finger keyboard (2 left 3 right) and printed/punched on
ticker tape. Baudot keying was synchronized with a mechanical timer that alternately unlocked the keys and advanced the ticker tape on the receiving end about 8 to 10 times a second--advance,unlock,punch,lock,advance....
The codes were arranged so that the frequently-used letters required the least amount of keys pressed. Here is a Baudot table, arranged for operator keying:
5 4 L F 3 2 1 5 4 L F 3 2 1
--------------- ---------------
A 1 * * - . *
E 2 * * X 9/ *
Y 3 * * S 7/ *
/ 1/ * * * Z : * *
I 3/ * * * W ? * *
U 4 * * * T ^2 * *
O 5 * * * * V ^1 * * *
* J 6 * * * K ( *
* G 7 * * * M ) *
* B 8 * * * R - *
* H ' * * * * L = * *
* F 5/ * * * * N £ * *
* C 9 * * * * Q / * *
* D 0 * * * * * P + * * *
Control Codes
5 4 3 2 1
---------
* Space and Figures follow (F row)
* Space and Letters follow (L row)
* * Error, delete previous character
Keyboard mapping:
- Right ring finger
- Right middle finger
- Right index finger
- Left index finger
- Left middle finger
The 1/ 3/ 5/ 7/ 9/ were used to transmit
fraction numerators for
stock market quotes.
For example:
M S F T 2 4 1/8 I B M 8 3 3/4
--------------------------------------------
\ o o o o o o o \
/ o o o o o o o o /
\ o o o o \
/ o o o o o o o /
\ o o o o o o o o o o o \
--------------------------------------------
- Can you guess which symbol actually was written to ticker tape at one point?
- Did you notice the + symbol is all holes punched, and three in a row means 'tear off here'. There's something familiar about that ...