The Special Fish Report
Albert W. Small (December 1944)
Codes and Ciphers
TOP SECRET Special Fish Report Page 111
Now suppose it is desired to count in the same counter all the places
wherein either . . x . . or . . . . . occurs. If we throw keys E1 E2 E4 E5 up and E3
and C1 down, and then up keys E6 E7 E8 E9 E10 and down C6, that will make counter 1
count places wherein . . x . . AND . . . . . SIMULTANEOUSLY occur. This is not
only impossible, but it isn't what was wanted. But if we up keys E1 E2 E4 E5 and
down keys E3 C1 and down negativing key N1, so that counter 1 now counts
all position that are NOT(. . x . .), and then in addition throw up keys
E6 E7 E8 E9 E10 and down keys C6 and N2. counter 1 must now count all positions
that are SIMULTANEOUSLY NOT(. . x . .)AND NOT(. . . . .) The negative of
this condition may be counted in counter 1 however by throwing negativing
key N16 down. If this is done counter 1 now counts all positions that are
NOT: SIMULTANEOUSLY NOT(. . x . .)AND NOT(. . . . .) or in other words that are
EITHER . . x . . OR . . . . . It is really quite simple.
The "M" key left alone does nothing; with it up Colossus counts only
if the motor is a dot; or down, only when the motor is a cross.
The undesignated keys are used in multiple testing wherein five successive
positions are tested at once and the wheel-patterns stepped five notches each
time; in such cases these keys must be thrown down and other plugging done on the
jack control board to provide for five positions stepping. Remaining controls are
not of particular interest to Arlington.
Colossus can do rectangling, the run being much like wheel-breaking runs.
X1 and X2 patterns are plugged up/with one cross and all the rest dots, These
patterns are run in all 1271 starting positions against delta Z; there is a "depth"
switch that can be thrown, so that the answers will be doubled and have the depth
subtracted from them, and therefore print out as excess of dots over crosses
(positively or negatively.)
It is planned to have a total of 12 Colossi.