Раздел 4 Первое занятие

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operations in a second. But the computer is not superhuman for it can accomplish²¹ none of these things by itself. Every computer now in ex­istence must be told what to do: it must have a set²² of instructions. These instructions are called a program. The writing of these instruc­tions is called programming. Programming is done by a man.

Surely²³, there are similarities with human brain, but there exists one important difference. Despite²⁴ all its accomplishments, the elec­tronic brain must be programmed by a human brain.

Although accepted for different purposes, computers virtually do not differ in structure. Regardless of²⁵ their size or purpose most com­puter systems consist of three elements: the input-output ports²⁶, the memory hierarchy and the central processing unit.

The input-output ports are known to be paths (каналы) where­by²⁷ information (instructions and data) is fed²⁸ into the computer or taken out of it.

There are several types of memory. Memory is essential to the computer’s operation. Items²⁹ of information can be written to, stored³⁰ in, retrieved³¹ from it on demand by the central processing unit, or erased³² to make room (место) for other information.

The central processing unit, or CPU, controls the operation of the entire system by issuing³³ commands to other parts of the system and by acting on the responses. When required, it reads³⁴ information from the memory, interprets instructions, performs operations on the data accord­ing to the instructions, writes the results back into the memory, and moves information between memory levels or through the inpui-output ports.

Advances in microelectronic components led to the development of smaller computers. In 1971 Intel. Corp. delivered the first micro­processor, the 4004. The central processing unit of a computer was put onto a single silicon chip less than 1/4 in square. When a central pro­cessing unit (CPU) of a computer is implemented³⁵ in a single, or very small number of integrated circuits, we call it a microprocessor. When a computer incorporates³⁶ a microprocessor as a major component, we call it a microcomputer. When the entire computer, including CPU, memory and input-output capability, is incorporated into a single IC, we call the latter a one-chip microcomputer.

The first design was followed by many others. The progress to­ward smaller computers is certain to continue: gradually there ap-

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Микроэлектроника настоящее и будущее

реаг /ш/20-computers and pico-computers. These computers are more flexible³⁷. Modern computers are virtually symbiotic.

Advances in microelectronics give rise to advances in comput­ers. Computers today are providing an expanding range of services.

Computers are classified by size and capability as microcom­puters, mainframes³⁸ and supercomputers, depending on the size of their main memories and on their processing speed.

Most microcomputers are mostly used by individuals.

Mainframes are used by large corporations, government agen­cies (учреждения) and other large institutions.

Supercomputers are the largest and fastest of all computers. They have memories and processing speeds that may be measured in pico­seconds (trillions of a second). The boundaries separating the cate­gories change frequently as computer technology advances.

2. If hardware³⁹ is the body of a computer then software⁴⁰ is its soul (душа). Software is the term applied to the sets of instructions called programs. The writing of these instructions is called computer programming.

Several developments have helped to reduce programming ef­fort. High-level languages have replaced assembler languages to a great extent. These high-level languages, however, require more compila­tion and running time, and more memory space. One of the most important causes of the man-machine communication barrier is that an interactive computer system typically responds only to commands phrased with total accuracy in a highly restricted⁴¹ artificial⁴² lan­guage designed specifically for that system. If a user fails⁴³ to use this language or makes a mistake, however small, an error⁴⁴ message⁴⁵ is the response he can expect.

There is a trend⁴⁶ towards languages with free format and more error checking⁴⁷.

Just as the hardware designer needs fewer components to build a system, the programmer needs fewer lines of code to make a system go. Many scientists are known to have been conducting a research on man-machine communication. The work is ongoing. Of particular interest are information systems that model complex real-world events.