Solving the Enigma

short 3-wheel run. Although the installation is slow and space consuming, it has definite advantages in rapid wheel changes, remote control, and flexibility for handling special problems.

4. The following table shows a comparison of various aspects of the two installations. Most of the figures given below are only approximations.

Feature	Op-20-G Bombe	S.S.A. Bombe
Total Machine Cost	6 million	1 to 1 1/2 million
number of effective machines	121 (4 wheel)	10 (3 wheel)
Typical Day's Output	40,000 short 3-wheel runs 1,000 long 4-wheel runs	1,200 short 3 wheel runs long 4-wheel runs not possible
Rate at which Machine Tries Assumptions	20,280 [tries] per second	910 [tries] per second
Running Time	50 seconds per short 3-wheel run 20 minutes per long 4-wheel run	10 minutes per short 3-wheel run Long runs not possible
Operations Personnel	700	20
Maintenance Personnel	135	40
Total number of Enigma Equivalents	1,936 wheel banks	144 Relay Banks
Type of detection	Print only correct "stories"	Print all "stops" which are then hand tested to find correct "stories"

Respectfully,

John Wenger

Notes:

1. J.N. Wenger, "OP-20-G Memorandum" dated 12 February 1945, (NARA Record Group 475, File 35701.)

2. S. S. A. expands to Signal Security Agency, which was the name of the crytologic section of the Army at the time.

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