12. Ciphers

It is easy to think of computers as giant calculators, and indeed the task of calculation and its mechanisation contributed both to the idea of constructing such a machine and to the conception of the tasks to which it might be addressed. Difficult calculation tasks such as those involved in ballistics (particularly in wartime) provided some of the stimulus towards the post-Second-World-War development of computers. But we have just seen, in the previous chapter, how a really rather different..