Virtual Wartime Bletchley Park
by Tony Sale

Exploring the Turing Bombe in action

This high speed simulation of a Turing Bombe has been developed to enable the breaking of real Enigma intercepts in a reasonable time.

It has been written in compiled Modula 2 code and at maximum speed on a 350 MHz PC runs about 60 times faster than the original 1940's Bombes. It takes about 20 minutes to go through the 60 wheel orders for the Army/Air Force set of 5 wheels. There may be faster simulations, but this one contains all the details required to exactly simulate and demonstrate the real Bombe.

It needs to be downloaded from a ZIP file and then unZIPped into a folder on your hard disc. It needs about 2 MBytes of space but note that because this is an IBM PC .exe file it may not run on an Apple Mac.

Click here to download the bombe.zip file.

You will also need to download the 1944 US 6812th Report on the British Bombe from the Document Archive section of this web site. The following Bombe runs are based on the Menus in this Report. The Text setup file names refere to the figures and Menus in the Bombe Report, i.e. brfig20.txt.

Getting Started

If you are new to the Turing Bombe you might like to read the introduction to the Turing Bombe in VirtualBP/tbombe/tbombe.htm.

Although there is a Help page on the Bombe page when it is running, you might wish to print this page for reference.

You need to be running this page ( intro.htm ) from the folder into which bombe.zip has been unZIPped.

The Bombe Simulator

The simulator program is bombe.exe. Unfortunately HTML does not allow you to run a .exe program from within an HTML document. It has to be run by exiting the HTML page and just running bombe.exe.

When the Bombe simulation loads it presents a setup form in the top left hand corner of the screen with a picture of ATLANTA, one of the Bombes in the US wing at Eascote, in the background.

Data can be entered manually into this setup form but the prefered method is to prepare a text file from which the data is loaded into the form.

ALL FIELD DATA AND FILE NAMES MUST BE IN CAPITAL LETTERS.

Any simple text editor can be used for this, I use Wordpad or Edit. The data is entered comma seperated and terminated with a semicolon, all on one line. The text files must be in the same folder as bombe.exe.

To take data in from a text file, click 'Setup' on the menu bar on the setup window. Then type in the name of the required text file into the Setup text window and click OK. The data will appear in the setup form. This can be modified if required before clicking OK on the setup form.

When OK is clicked an image of the menu being run overlays the Help window.

By clicking on 'Search' on the Setup text window menu bar, a list of all text files can be scrolled through in the left hand window. Double clicking on the required name transfers it to the data field in the Setup text window, a lot quicker and easier than keying the name in.

To run the Bombe on the data in the setup window, click on 'trace' to run in (slower) trace mode or 'run' to go at maximum speed. If trace is selected then a display of the Bombe registers appears in a window at top right with a Results window bottom right. If 'run' is selected then just the Results window appears. When a stop is found by the Bombe it is displayed on a line in the results window. Clicking 'Next' on the menu bar of the results window causes the Bombe simulator to resume searching for any more stops. Clicking 'Quit' on the Rersults window or the 'Finish' button on the Setup window stops the Bombe and then clicking 'Quit' on the Setup Window menu bar takes you out of the Bombe program.

Data and Options in the Setup Window

"Bombe Setup"
from-text: XXXXXXXXXXXXXX
menu-image: XXXXXXXXXXXXXX
wheel-order-start: XXX
wheel-order-end: XXX
max-wheels-5-or-8: X reflector: X
ukw-d-plugging:
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
wheel-letter-start: XXX
input-at: X current-at: X csko: X
stop-at-menu-item: X stop-each-letter: X
test-all: X machine-gun: X
Menus:
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

from-text: is the name of the text data file, this is copied in for reference.
menu-image: is the name of the bitmap (.bmp) menu image, if any.
wheel-order-start: is the starting wheel order for the simulation runs.
wheel-order-end: is the last wheel order to be done before the Bombe stops.
max-wheels- sets either a 5 or 8 wheel run. (Army or Navy).
reflector: is usually B although C is included. If 'D' is set then the next field contains the letter pairs of the plugging seperated by a space.
wheel-letter-start: sets the start wheel letters.

input-at: is the register letter at which the input current is to be injected.
current-at: is the input current letter in the input register.
csko: 'Y' forces a rejection of stops which contain consecutive steckers.
stop-at-menu-item: 'Y' allows single stepping through each menu item in trace mode.
stop-each-letter: 'Y' forces a stop after each iteration through the complete menu in trace mode.
test-all: 'Y' forces a check that all registers involved reach 25 before a stop is produced.
Note this is an extension over the original Bombe which could only test one register. If this field is set to 'N' then that is what the simulator does.
machine-gun: if set to 'Y' only stops which pass the machine gun test(see below) are printed.
Menus: contain the menu items in 4 character groups, blank seperated with a comma and no blank after every six items.

The format for these menu items is as used to teleprint menus from BP to Bombe outstations in WWII. First two letters are the register letters involved in the link, the last two letters are the wheel offsets for middle and right hand Enigma wheels, (middle and bottom Bombe drums). The left hand wheel, (top drum) is assumed set to 'Z'.

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This page was originally created by the late Tony Sale
the original curator of the Bletchley Park Museum

Virtual Wartime Bletchley Park by Tony Sale

Exploring the Turing Bombe in action

Getting Started

The Bombe Simulator

Data and Options in the Setup Window

Virtual Wartime Bletchley Park
by Tony Sale