The Special Fish Report Albert W. Small (December 1944) Page 108

Tony Sale's Codes and Ciphers

| previous page | next page | index page |

CX/MSS
TOP SECRET Special Fish Report Page 108



photocells for each tape, so that a pair of adjacent levels may be read

simultaneously and differenced. Thyratrons count units of 1, 2, 4, 8; high

speed relays count units of 16, 32, 48, 64; nickel-iron relays count 80, 160,

240, 320, 400, 800, 1200, 1600; standard telephone relays ("P.O. 3,000") count

2,000, 4,000, 6,000, and 8,000. Tape lengths possible on the bedstead are from

2,000 to 1l,000. DOUBLE ROBINSON: (two built) Same as above but double

Robinson has 2 bedsteads and photocells racks, so it can read from 4 tapes

at once. NEW DOUBLE ROBINSON (under construction): same as the double Robinsons

just mentioned, except that it will have vacuum tube counters, and will

permit multiple testing. Other Robinson are

being converted to this type later.


COLOSSUS: Bedstead has positions for two tapes, but only one runs


at once. Each tape travels past only one set of photocells. Tape is driven by

friction between tape and the wheels, without the use of sprocket-pull as

in Robinson. Colossus has vacuum tube: chi pattern generator, psi pattern

generator, and motor pattern generator; also has a vacuum tube memory so it

can delta. "Triggers" (rotary telephone switches in this case) select

any of 5 sets of wheel patterns for chi, psi, and motor wheels, each set of

which my be plugged up at will and selected at will. There are five counters,

which may all work at once if desired, and when counters are overloaded

the machine runs idly (without stepping the wheel-patterns) until the counters

print out and are clear again. "Span counters" permit the selection of a stretch

or span of tape for study, eliminating all before and after the counting.


Colossus has a jack board for plugs, to be used in controlling it;


and also a key board. The key board may be used instead of the plugs for most

runs and is more convenient, or in conjunction with the plugs. The "keys" are

switches whose levers have "center," "up" and "down" positions, or in some

cases only "center" and "down." A schematic of the key board appears next page.





---




| previous page | next page | index page |