THe National Cash Register N-530 Bombe Enigma Decrypting Machine

National Cash Register Company Main Page
The National Cash Register N-530 Bombe Enigma Decrypting Machine
(U.S. Navy Cryptanalytic Bombe)
Dayton, OH

This page added 12-29-2022.

During World War Two, the German U-Boat was the Royal Navy's and the U.S. Navy's "Public Enemy Number One." Author's photo of U-505 at the Museum of Science and Industry in Chicago, IL.

Encrypted messages were sent between German Navy submarine headquarters and U-boats in the North Atlantic using the German Navy's Enigma coding machine. The result was the massacre of freighters and tankers bringing food, ammunition, weapons, and everything else Great Britain needed to survive the German offensives against its military forces throughout the world. Messages could be decrypted by hand in some cases, but by the time they were, it was too late. Ships had already been sunk by submarines after being given the location of the slow convoys making their way across the Atlantic. Something faster was required. The solution was the National Cash Register N-530 Bombe Enigma Decrypting Machine.

During World War Two, this German Navy Enigma coding machine was "Public Enemy Number Two" to the Royal Navy and the U.S. Navy. All photos on this page, unless otherwise stated, were taken by the author at the National Cryptologic Museum in May 2016.

The National Cash Register bombe was based on a similar machine invented by Polish Intelligence previous to the German invasion in 1940. It was further improved by Alan Turing at Bletchley Park in England where German messages were decrypted. However, the U.S. Navy wanted its own bombes and National Cash Register was contracted to make these under a very top secret project. The bombe shown here is the only surviving one left of the 121 built.

It was one of only two American top secret projects during World War Two to remain a secret. The other was the VT Proximity Fuze. The Manhattan Project had several Russian spies in it.

There is a plethora of written literature and websites that detail the entire battle to decode German and other Axis secret codes and how the bombe came to be to assist in winning the war. This page will not delve into that, as it is well documented on other places.

This page will examine the last surviving National Cash Register N-530 Bombe Enigma Decrypting Machine that is on display at the National Cryptologic Museum at Fort Meade, MD.

The Museum had this display of several types of Enigma machines in 2016.

The following series of photos will include both photos taken with and without flash. Those without flash will have reflections as the entire bombe is enclosed in a glass case. It is the nature of the beast.

The Museum identifies the bombe as the U.S. Navy Cryptanalytic Bombe.

This shows the size and complexity of the N-530. It was seven feet in height, ten feet long, and weighed 5,000 pounds.

This photo shows several NCR-530s in operation in Washington, DC.

Next will be a series of photos that explain the different parts of the N-530 Bombe.

The next two photos show the switch banks on the N-530.

This shows the nuts that required a special wrench.

The amplifier chassis on this machine is marked 102. The two switches also needed a special wrench to set it. The WAVES may have needed to stand on a stool to set these two switches, as the machine was seven feet in height.

The Thyratron chassis is the bottom chassis to the left of the wood glass support.

This is the back side of the N-530. The amplifier chassis is on the right, with the Thyratron chassis located at bottom left. It is the one with all of the tubes in it. These were the Bombe's memory.