Text 10. Memory

The electronic “memory” of a computer is a depot to store numbers and instructions. From this depot they are sent for processing to “the mathematical mill”. The results obtained are returned to the “memory”.

It may be said that the history of progress in high-speed compu­ters coincides with the history of the improvement of their “memo­ry”. Quite recently the electron tube “memory was considered high­speed “memory”. Next the ferrite-core “memory” was produced. The working speed of most up-to-date computers holds up to ten million bits. To increase the capacity and data production speed are the most important aims of contemporary computer construction. Tunnel dio­des, thin magnetic films — these so called microminiaturization ele­ments are used to construct the “memory”.

Memory consists of three elements: storage, read and write circuits, and address selection. But any storage system requires these three ele­ments. What distinguishes a memory from other types of storage?

To answer this question, let us look at different classes of storage. Storage may be classified according to size. There is bit storage, as exemplified by the flip-flop; there is word storage, as exemplified by the register and counter; and there is multiword storage which is exemplified by systems of bulk storage.

Storage may be classified according to whether it is external or internal. External storage exists outside the computer; it is not a fundamental part of the computer. Internal storage is an integral part of the machine; without it the computer cannot function.

Storage may be classified according to whether it is fixed or eras­able. The contents of fixed storage cannot be changed. The contents of erasable storage can be changed — it can be written into.

To be considered memory, storage must be:

1. Bulk storage. 2. Internal. 3. Erasable.

Obviously one bit or one word cannot constitute memory; we need a device which can store many words. Internal storage implies that there is ready and quick communication between memory and the other functional units of the computer. Erasibility means 2-way ac­cess to words in memory, in as well as out.

To summarize, we may say that memory is accessible bulk storage which may be written into as well as read from.

External storage is used in the input and output systems. Fixed storage may be used in the control unit for storage of nonchangeable programs in special-purpose computers.

Modern science considers that many branches of knowledge depend to a great extent on the solution of the problem of human memory and on the levels of development of artificial computer memory.

Notes

depot f'depou]	- сховище, склад
to process ['prousas]	- обробляти
to coincide [,kouin'said]	- збігатися
capacity [ka'pæsiti]	- обсяг
diode ['daioud]	- діод
film	- плівка
flip-flot	- ляскаючі звуки
counter bulk [bAlk]	- лічильник - більша частина; основна маса
multiword	- багатослівний
to exemplify [ig'zemplxfai]	- бути прикладом
erasable [I'reizabl]	- який стирається
erasibility [i^eizi'biliti]	- здібність стирати
to summarize ['sAmaraiz]	- підсумовувати
accessible [aek'sessbl]	- зручний
solution [sa'lui/n]	- вирішення