Other Parts Required

In early 1998 we carried out a comprehensive investigation into the standard BTM parts that are required for our Target Bombe. A detailed list was then produced, followed shortly afterwards by an illustrated supplement. This were called our shopping list and copies went out to about a dozen ex ICL people who are knowledgeable on circa 1940 Punched Card equipment.


We were very fortunate with the response to our appeal for these standard Hollerith parts. Many ex BTM/ICT/ICL employees had helped. The result was that with very few exceptions we then had an example of every part we required. Should we have needed any parts or components re-manufactured, then at least we knew exactly what was required. I am very grateful to all those who are helping with this exercise.

Parts were found from all over the world with the last major discovery being in New Zealand. The Otago Peninsular Museum in Dunedin were very helpful and donated many valuable components

Our most serious remaining BTM shortages now are

Multi Relays

Seven are needed to replace slightly incorrect but genuine BTM relays that were used elsewhere in the Bombe. We have now have five and therefore we need two more plus, if we were lucky, a couple of spares.

We require a minimum of seven Multi Relays, each with 12 sets of contacts. These were fitted to both BTM and IBM Punched Card equipment such as the reproducer and Senior Rolling Total Tabulator. The BTM part number is 927587 and we believe that the same part number was used by IBM. So far we have been only partly successful in our search for these . As these relays have been found from time to time we continue to be hopeful that the rest will somehow appear.

Removable part/control panel assembly


We have six of these. This has allowed us to wire up three as “B” (Butter) board reflectors and one as a special ‘straight through’ test item. This leaves two but we really need sets of three. The Bombe is fully operational as it is but if we wished to experiment with alternative reflector configurations or perhaps make available connections for a permanent re-pluggable reflector ‘D’ sub assembly, more would be required.

The single versions, shown above and below, were used on the majority of BTM and IBM machines. A whole variety of part numbers were used to cover very minor variations so this information is not of much use. However we would like more that we could plug up in sets of three to represent alternative “Uncle Walters”. Many of these panels were supplied with punched card equipment to be plugged up (programmed) to run a specific job. They may well have stayed on customer’s premises after the original machine was disposed of. We hope that some have survived


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