1. the reception of 'information';
2. the storage of this information (memorising);
3. ability to recall the stored information when required;
4. the initiation of appropriate action based upon selected items of the stored information, in response to a suitable stimulus;
The main differences between a human brain and an artificial 'electronic' brain are in the manner in which information is applied, stored, recalled and utilised.
In the human brain, information is received via the senses - sight, hearing, touch, smell and taste. The electronic brain, however, receives information only in the form of electrical impulses, meaningless in themselves, but having specific significance when applied according to a suitable code. This coding, of course, must be performed by an external agency - human, .mechanical or electrical, or by a combination of these. Examples of such agencies are perforated-card systems, light-sensitive devices, and tempera- devices.
The mechanism of information storage in the human brain is not precisely known, but there is good evidence that it is partly, if not entirely, electro- In 'electronic' brains information is usually stored in the form of different conditions of magnetisation or of electric charge, in a number of 'memory elements'.
The recall of previous impressions or stored information in the case of a human brain may be a simple act of will, or imagination, or the reception of some similar or related impression - for example, a particular scent may recall memories of a pleasant evening spent with a girl who used the same perfume. In the case of an electronic brain, however, the recall of stored information can result only from the application of further coded impulses, again controlled by human agency.
Initiation of action in the case of a human brain may again be an act of will, or it may be semi-automatic -.as when a feeling of burning causes one ,to withdraw one's hand from a hot tea-pot handle - or it may be entirely automatic, such as the beating of the heart. With electronic brains, however, initiation of action occurs only as a result of a specially applied coded signal. It will thus be clear that the potentialities of the electronic brain are in many respects subject to severe limitations compared with the potentialities of the human brain. In particular, the electronic brain possesses no will power, no imagination, no sentimentality, and no discretionary power. On the other hand, a given code signal will always result in the storage of the same information, or the recall and utilisation of the same selection of the stored material. Furthermore, unless some failure occurs in the electrical system, an electronic brain cannot make mistakes due to incorrect calculation or lack of judgment.
The limitations of the electronic brain stem from the fact that, whereas the human brain deals, in the main, with impressions, sensations, facts and ideas, the electronic brain deals only with numbers - and coded numbers at that.
This tutorial is concerned with the particular form of artificial memory equipment which operates on the principle of patterns of different conditions of magnetisation in a complex of magnetic elements.