TEXT A. MEMORY OR STORAGE UNIT

1. The part of a digital computer which stores information is called storage or memory. The computer's memory stories the numbers to be operated on; it stores intermediate results that are generated during the course of a computation; and it stores the final results. The instructions themselves are also stored in the computer's memory.

2. There are two important factors about the memory unit: an access time and a capacity. The time required to transmit one computer word out of the memory to where it will be used is called the memory access time; it usually amounts to a few millionths of a second or less in modern fast computers. The speed of modern computers is the speed of access to their memories. The capacity of a computer is the quantity of data that its memory unit can hold.

3. There are many ways of memorizing information in memory cells of a digital computer. External memory or storage units may use magnetic tapes, magnetic drums," magnetic disks and floppy disks. The magnetic drum and magnetic disk are called a Direct Access, or Random Access, Storage Device (DASD).

4. The magnetic disk is very similar to the magnetic drum but is based upon the use of a flat disk with a series of concentric circles of magnetizable material, one read/write head, being for each concentric circle, i.e., for each track. Memory units on magnetic disks may store more than 100,000,000 bytes. The magnetic disk is illustrated in Figure 1.

5. Internal or main memory units were constructed of magnetic cores about 8 hundredths of an inch in diameter, each core storing one 'yes ' or 'no', that is, each core representing one bit of information.

6. Information that is stored inside a computer is stored in registers, electronic units of hardware in which the positioning of physical objects stores information. Each register holds one machine word consisting usually of 32 bits or 4 bytes. Registers hold information temporarily during processing. The slower models of registers use magnetic cores; the faster models use special electronic circuits or film memory devices.

7. Usually the registers are of three types:

1. General-Purpose Registers are sixteen registers, each being able to contain one word. These registers are used for storing the integer operands taking part in binary arithmetic operations.

2. Floating-Point Registers are four registers, each being able to contain a doubleword. These registers hold the operands taking part in arithmetic operations on floating-point numbers.

3. Control Registers form a group of registers differing from one model to another.

8. The development of semiconductor integration technology has led to creation of memories on LSI circuits. For constructing memory units on LSI circuits either bipolar or MOS memory are used. The access time of bipolar memory is about 100 nanoseconds, while the access time of MOS memory is 500 nanoseconds. But on the other hand the density of memorizing elements allocation in the latter is very high and amounts to 4 thousand memorizing elements for one chip. The latest achievements of modern electronics are creation of memories on electronic circuits made by spraying layers of different memorizing materials.

9. Nowadays the main memory RAM which is regularly used in microcomputers can accept new instructions or information from a peripheral device. Terms synonymous with the computer's working memory RAM are: core, core storage, main memory, main storage, primary storage, read/write memory. Other memories, such as ROM or PROM, which are used in microcomputers as well, store instructions or information permanently. ROM, PROM, EPROM, and EEPROM are all together called firmware which is 'hard' software.

Exercises

IV. Find the equivalents:

V. Memorize the following definitions:

1. Memory unit is a part of a computer which stores information. 2. The memory access time is the time required to transmit one computer word out of the memory to where it will be used. 3. The capacity of a computer memory is the quantity of data that the memory unit can hold.

VI. Answer the following questions:

1. What is the general purpose of the memory or storage unit? 2. What information is stored in the computer memory? 3. Where is information stored inside the computer? 4. What is the memory access time? 5. What ways of memorizing words in a computer do you know? 6. What has led to creation of memories on LSI circuits? 7. What are the latest achievements of modern electronics? 8. What memories are used in microcomputers?

VII. What do you call a unit which:

1) accepts information from outside a computer? 2) memorizes information to be operated on? 3) brings information out of the computer? 4) is able to take in information at the very high speed from a computer and then release it at the proper speed for the peripheral equipment?

VIII. Translate the following sentences paying attention to the words in bold type:

a) 1. Every student must know that reasonable operations are logical and mathematical operations. 2. His experiment is simpler than that of yours. 3. The capabilities of a digital computer are greater than those of an analog computer. 4. It is clear that these diagrams are like those shown in Fig. 4.

b) 1. As science progresses the difference between man-made systems and natural systems may be reduced infinitely (бесконечно). 2. As you know information is a set of marks that have meaning. 3. As new operations can be composed of sub-operations, no new programming is needed. 4. The development of computers as machines for handling information has gone a long way. 5. As is known, program is a set of instructions.

c) 1. One of these problems has been solved by a computer. 2. By means of a computer one can easily solve any problem. 3. There is only one solution, the one stated above, when n and m are equal 4. One should remember all these rules, while solving a problem.

IX. Translate the following sentences paying attention to the form and function
of the Participle:

1. The input unit consists of some devices using different means. 2. Performing addition the computer must have two numbers to be added. 3. When pressing the keys the operator makes the adding machine operate. 4. The operator pressing the keys makes the adding machine operate. 5. A device invented by the German mathematician Leibnitz could control automatically the amount of adding to be performed by a given digit. 6. Logical operations performed by a computer are comparing, selecting, sorting, and determining. 7. Discussing the advantages of the new memory unit the professor gave the students all the necessary explanations. 8. Having punched holes in a card the operator put it into the computer. 9. When passed through the reading equipment the characters are read in a way similar to a way used for a magnetic tape. 10. The density of memorizing elements in MOS memory is very high.

X. Translate the following sentences paying attention to the Absolute Participle Construction:

1. The first automatic computers of the 1940's not being very reliable, scientists went on improving them. 2. Specialists use computers widely, the latter helping in performing computations at great speeds. 3. Personal computers being used for many put poses, scientists go on improving their characteristics. 4. The computer SM-100 is used in industrial processes and scientific researches, its main function being to carry out reasonable operations with numbers and to calculate complex problems. 5. With the current on, the computer automatically begins operating. 6. A printer's line is usually between 60 and 150 characters long, with 120 characters being a common length.

XI. Find the sentences in which the Absolute Participle Construction is used:

1. Register R storing the code for number 3, the computer will perform the operation 3 times. 2. When storing the code for number 3 register R makes the computer perform the operation 3 times. 3. The computer performs the operation 3 times, the code for number 3 being stored in one of the registers. 4.The register storing the code for number 3 is arranged in the computer's - memory. 5. The code for number 3 being stored in register R, the operation will be performed by the computer 3 times.

XII. Read Text В without a dictionary. Express its contents by 3-4 sentences:

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