CHAPTER II. PROCEDURE USED IN MACHINE DECODING. TOP SECRET-T
The 6812th Signal Detachment functions as a component part of the
organization associated with Hut 6,Bletchley Park, the purpose of which is
to decode enemy enigma traffic. The departments in and associated with Hut
6 are: -
Intercept stations located in England, France, the Middle East, and
at the fighting fronts sending in 3000 to 4000 messages daily.
Registration Room where messages are received and sorted according to
key. (Blist, -Bannisters List).
Air Watch, Army Watch, and Research Dept. responsible for breaking
the messages and preparing cribs.
Machine Room responsible for details of running Bombes and for
contact with OUT Stations.
Bombe Organization Out stations of which 6812th Signal Security
Detachment is one.
Decoding Room takes the key found by the bombe, decodes the messages
and sends them to Hut 3 (Intelligence) via the Air Watch or Army
watch. These watches need to see the completed decodement for
information on future cribs.
Hut 3(Intelligence) distributes the information in the decoded
messages to the points needing such information, taking care to so
disguise the information that the Germans won't realize from the
results that the enigma traffic is being broken.
This detachment functions as one of the Out Stations, of which there are
six, namely Bletchley Park, Adstock, Gayhurst, Eastcote, Stanmore and USA.
USA is physically located in Out Station Eastcote, but operates as an
independent unit. USA has only one bay. The machines within a bay are named
for cities of the country concerned. USA has ten bombes named as follows;
Atlanta, Boston, Chicago, Houston, Minneapollis, New York, Atlanta
Philadelphia, Rochester, and San Francisco. Boston, Chicago and New York
are of the so-called 39 point type and the others are of the 30 point type.
The outstations are operated on a 3 shift, 24 hour basis. In USA the shifts
are O000 to 0800, 0800 to 1730,and 1730 to 2400. The personnel is divided
into 4 "watches" A,B,C,and D of 30 men each. Each watch is divided into one
IC OPS (In Charge of Operations), one Assistant IC OPS, ten teams of 1
operator and I checker each, one engineer, either three or four technicians
and the balance of the "watch" as substitute operator-checkers.
The "watches" work on a rotating schedule which keeps a "watch" on each
shift for approximately one week.