The US 6812 Division Bombe Report Eastcote 1944 Page 42

Tony Sale's Codes and Ciphers

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- 37 - TOP SECRET-T
positions ZZD,ZZE and ZZF under these conditions it is known that the first
letter of the indicator is coupled to both U and Z. On the menu this is
shown U -- ? -- Z. A typical menu would look like this:




Fig. 32. Typical Query Letter Menu.


It is plugged by merely tying those ends of enigmas serving query letters
(?) together with commoning plugs, not patching them to the diagonal board.
On the check sheet the query letters are identified by numbering. The
steckers for the query letters are set down in a separate column. When the
stop is evaluated the query letter steckers are disregarded.

Middle Wheel Turnover Menus. - This type of menu is used for "top and tail"
cribs in which cribs have been made of the heading and closing of a message.
In such a case it is assumed that the middle wheel has turned over and moved
the slowest wheel at least one position. The bombe operator is asked to run
first at ZZ- settings and then make the same runs with these wheels
advanced. The following is a sample of such a menu:




In this menu it is assumed that for settings ZF- the middle wheel turns one
position and that its notch was effective and moved the slowest wheel one
position. The resultant positions are AG-.



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