2. Composition of the Calculator.
We list here the main components of the calculator as at present conceived:–
(1) Erasible memory units of fairly large capacity, to be known as dynamic storage (DS). Probably consisting of between 50 and 500 mercury tanks with a capacity of about 1000 digits each.
(2) Quick reference temporary storage units (TS) probably numbering about 50 and each with a capacity of say 32 binary digits.
(3) Input organ (IO) to transfer instructions and other material into the calculator from the outside world. It will have a mechanical part consisting of a Hollerith card reading unit, and an electronic part which will be internal to the calculator.
(4) Output organ (OO), to transfer results out of the calculator. It will have an external part consisting of a Hollerith card reproducer and an internal electronic part.
(5) The logical control (LC). This is the very heart of the machine. Its purpose is to interpret the instructions and give them effect. To a large extent it merely passes the instructions on to CA. There is no very distinct line between LC and CA.
(6) The central arithmetic part (CA). If we like to consider LC as the analogue of a computer then CA must be considered a desk calculating machine. It carries out the four fundamental arithmetical processes (with possible exception of division, see p. 27), and various others of the nature of copying, substituting, and the like. To a large extent these processes can be reduced to one another by various roundabout means; judgment is therefore required in choosing an appropriate set of fundamental processes.
(7) Various ‘trees’ required in connection with LC and CA for the selection of the information required at any moment. These trees require much more valve equipment than LC and CA themselves.
(8) The clock (CL). This provides pulses, probably at a recurrence frequency of a megacycle, which are applied, together with gating signals, to the grids of most of the valves. It provides the synchronisation for the whole calculator.
(9) Temperature control system for the delay lines. This is a somewhat mundane matter, but is important.
(10) Binary to decimal and decimal to binary converters. These will have virtually no outward and visible form. They are mentioned here, lest it be thought they have been forgotten.
(11) Starting device.
(12) Power supply.