The Manchester Automatic Sequence Controlled Calculating Machine has been devised and constructed to undertake a wide variety of complex calculations which would take human beings, using ordinary methods, possibly months to carry out, where the machine takes only an our or so. The human controller has to decide how to Calculating Machine can perform the desired calculation, and draws up a list of "instructions" for it to obey. He breaks up the complex calculation into a series of simple basic operations and translates these from numbers into a specified code. The list of "instructions" is fed into the machine, and the initial numbers (in code) on which it is to operate are then loaded into a special position. All the information having been fed into the Calculating Machine, its "memory" can be switched on to start operations. When the machine has worked out the whole problem, a red light switches on and it stops automatically. The final result can then be read off the monitor cathode-ray tube (shown in our photograph) in the form of light dots which are translated into figures by the human controller. A photograph of the complete apparatus appears elsewhere in this issue.