| |
| | The ECM Mark II, also known as SIGABA, M-134-C, and CSP-889 |
 | | When using the machine, the ten 26-contact rotors were first set to their starting positions, which were the ones marked by the letter O instead of the ones marked with the letter A that one might expect, usually with the aid of an automatic feature in the machine. |
 | | Although the mechanical gears that usually moved the control rotors were not active during this setup mode, each time a number key was pressed, the cipher rotors moved based on the electrical signal travelling through the control and index rotors in the same way as during normal encipherment. |
 | | Machines of the ECM Mark II type used for a communications link between the President of the U.S. and the Prime Minister of the U.K., which was called "POTUS-PRIME", were operated in a fashion that produced additional security. |
| www.hypermaths.org /quadibloc/crypto/ro0205.htm (1796 words) |
|