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Bit – basic unit of memory
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Information is processed and stored in computers as electrical signals. A computer contains thousands of electrical circuits connected by switches that can only be in one of two possible states: ON (the current is flowing through the wire) or OFF(the current is not flowing through the wire). To represent these two conditions we use binary notation in which 1 means ON and 0 means OFF. This is the only way a computer can ‘understand’ anything. Everything about computers is based upon this binary process. Each 1 or 0 is called a binary digit, or bit.
Bytes and characters
1s and 0s are grouped into eight- digit codes that typically represent characters (letters, numbers and symbols). Eight bits together are called a byte. Thus, each character in a keyboard has its own arrangement of eight bits. For example, 0100001 for A, 01000010 for B and 01000011 for C.
The ASCII code
The majority of computers use standard system for the binary representation of characters. This is the American Standard Code for Information Interchange, known popularly as ‘ASCII’ (pronounced as ‘ask key’). There are 256 different ways of combining 0 and 1 bits in a byte. So they can give us 256 different signals. However, the ASCII code only uses 128 bytes to represent characters. The rest of the bytes are used for other purposes.
The first 32 codes are reserved for characters such as the Return key, Tab, Escape, etc. Each letter of the alphabet and many symbols (such as punctuation marks), as well as the ten numbers have ASCII representations. What makes this system powerful is that these codes are standard.
Kilobytes, megabytes and gigabytes
In order to avoid astronomical figures and sums in the calculation of bytes we use units such as kilobytes, megabytes and gigabytes. One kilobyte is
1,024 bytes (210) and it is represented as KB, or more informally K. One megabyte is equivalent to 1,024 kilobytes and one gigabyte is 1,024 megabytes.
We use these units (KB, MB, GB) to describe the RAM memory, the storage capacity of disks and the size of any application or document. For instance, the text of the book contains roughly 1 MB of information.
(E.C.U.)
Упражнение 24. Прослушайте текст и укажите, упомянуты ли дан - ные идеи в тексте (+/-):
Primary and Secondary Memory
1. The term ‘memory’ can be expressed in other ways.
2. Computers are often advertised according to their memory capacity.
3. The CPU can easily access information from internal storage.
4. Minicomputers and microcomputers have a similar memory capacity.
5. The control unit needs to know the location where information is stored or needs to be stored.
6. Primary memory is more expensive than secondary memory.
7. There are two types of secondary memory devices.
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8. Information stored on magnetic disk can be retrieved faster than if that same information were on tape.
9. Disks and tapes can be stored in a library.
10. Computers can process information even if complete programs are not put in internal storage.
Упражнение 25. Словам из левой колонки подберите соответству - ющие слова и выражения из правой колонки:
1) internal storage, a) means any part of memory can be read equally quickly,
2) real storage, b) the information contained in the storage locations,
3) random access, c) are storage locations in internal storage,
4) addresses, d) refers to memory,
5) contents, e) hooking up secondary memory devices onto memory to
increase their capacity,
6) sequential access, f) sometimes called primary memory,
7) virtual storage, g) information must be read from secondary memory
devices in a fixed pattern.
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Упражнение 26. Прочитайте текст и заполните пропуски данными ниже выражениями:
– All the information stored in the RAM is temporary
– Microcomputers make use of two types of memory
– ROM chips have ‘constant’ information
– the size of RAM is very important
Main memory: RAM and ROM
The main memory of a computer is also called the ‘immediate access store’, as distinct from any other storage memory available on disks. 1_______: RAM and ROM, both contained in electronic chips connected to the main board of the computer.
RAM stands for ‘Random-Access Memory’ and is the working area ofthe computer, that is, the basic location where the microprocessor stores the required information. It is called ‘random access’ because the processor can find information in any cell or memory address with equal speed instead of looking for the data in sequential order. 2_______, so it is lost when the machine is turned off. Therefore, if we want to use this information later on, we have to save it on a disk. When running an application, the microprocessor finds its location in the storage device (the floppy or hard disk) and transfers a temporary copy of the application to the RAM area. Consequently, 3_______ if we want to increase the performance of a computer, when several applications are open at the same time or when the document is very complex.
The RAM capacity can sometimes be expanded by adding extra chips. These are usually contained in Single In-line Memory Modules or SIMMs, which are installed in the motherboard of the computer.
We can designate a certain amount of RAM space as a cache in order to store information that an application uses repeatedly. A RAM cache may speed up our work, but it means that we need enough internal memory or a special cache card.
ROM is an acronym for ‘Read-only Memory’. Which implies that theprocessor can read and use the information stored in the ROM chip, but cannot put information into it. 4 _______, including instructions and routines for the basic operations of the CPU. These instructions are used to start up the computer, to read the information from the keyboard, to send characters to the screen, etc. They cannot be changed and are not erased when the power is turned off. For this reason, the ROM section is also referred to as firmware.
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(E.C.U.)
Упражнение 27.
a) Прочитайте текст:
Types of Memory
As mentioned previously, one of the most important characteristics of a computer is its capability of storing information in its memory long enough to process it. Not all computers have the same type of memory. In this section, three types of memory will be discussed: core memory, semiconductor memory (or chip), and bubble memory.
The memory of the first computers was made up of a kind of grid of fine vertical and horizontal wires. At each intersection where the wires crossed, there was a small ferrite ring called a core (hence the name ‘core memory’) which was capable of being either magnetized or demagnetized. Every intersection had its unique address; consequently, when an electric current was passed through the wires, the magnetized as well as unmagnetized cores were identified by their respective addresses. Each core represented a binary digit of either 0 or 1, depending on its state. Early computers had a capacity of around 80,000 bits; whereas now, it is not surprising to hear about computers with memory capacity of millions of bits. This has been made possible by the advent of transistors and by the advances in the manufacture of miniaturized circuitry. As a result, mainframes have been reduced in both size and cost. Throughout the 1950s, 1960s and up to the mid-1970s, core memory dominated the market, but it is now obsolete.
In the 1970s, there was a further development which revolutionized the computer field. This was the ability to etch thousands of integrated circuits onto a tiny piece (chip) of silicon, which is non-metallic element with semiconductor characteristics. Chips have thousands of identical circuits, each capable of storing one bit. Because of the very small size of the chip, and consequently, of the circuits etched on it, electrical signals do not have to travel far; hence, they are transmitted faster. Moreover, the size of the components containing the circuitry can be considerably reduced, a step which has led to the introduction of both minis and micros. As a result, computers have become smaller, faster, and cheaper. There is one problem with semiconductor memory, however: when power is removed, information in the memory is lost – unlike core memory, which is capable of retaining information during a power failure.
Another development in the field of computer memories is bubble memory. The concept consists of creating a thin film of metallic alloys over the memory
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board. When this film is magnetized, it produces magnetic bubbles, the presence or absence of which represents one bit of information. These bubbles are extremely tiny, about 0.1 micrometer in diameter. Therefore, a magnetic bubble memory can store information at a greater density than existing memories, which makes it suitable for micros. Bubble memories are not expensive, consume little power, are small in size, and are highly reliable. There is probably a lot more to learn about them, and research in this field continues.
(E. C. S.)
b) Просмотрите текст вновь и скажите, верны ли данные утвержде - ния. Измените предложения, содержащие неправильную информацию так, чтобы они тоже стали верными:
1. The most important function of a computer is to hold information in its memory in order to process it.
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2. Minicomputers, microcomputers, and mainframes all have the same kind of memory.
3. Semiconductor memory was developed before core memory and after bubble memory.
4. Core memory uses small metal rings which can be magnetized and unmagnetized.
5. The state of the core can be represented by either 0 or 1.
6. Early computer memories had less storage capacity than newer ones.
7. A transistor and a chip are the same kind of device.
8. The development of chips made it possible for minicomputers and microcomputers to be invented.
9. Bubble memory is smaller than a chip.
10. Bubble memory doesn’t have very many advantages.
| Storage Devices | |||
| Active Vocabulary | |||
| advantage | to erase | to record | sense |
| advantageous | eraser | record | sensible |
| disadvantage | erasure | recording | sensitive |
| tape-recorder | sensor | ||
| to afford | to fix | to seek | surface |
| fixed | |||
| apart | flexible | necessity | track | |
| apart from | flexion | to necessitate | to vary | |
| to cause | to insert | necessary | ||
| various | ||||
| rigid | ||||
| cause | namely | variant | ||
| entry | to search | |||
| search |
| Упражнение 28.Выберите правильный перевод: | |||||
| a) advantage | |||||
| 1) | поверхность | 2) | преимущество | 3) поиск | 4) чувство |
| b) to afford | |||||
| 1) | изменяться | 2) | записывать | 3) позволять себе | 4) вызывать |
| c) flexible | |||||
| 1) различный | 2) необходимый | 3) гибкий | 4) совместимый | ||
| d) sense | |||||
| 1) | поверхность | 2) | преимущество | 3) поиск | 4) чувство |
| e) to record | |||||
| 1) | изменяться | 2) | записывать | 3) позволять себе | 4) вызывать |
| f) surface | |||||
| 1) | поверхность | 2) | преимущество | 3) поиск | 4) чувство |
| g) to cause | |||||
| 1) | изменяться | 2) | записывать | 3) позволять себе | 4) вызывать |
| h) various | |||||
| 1) | различный | 2) необходимый | 3) гибкий | 4) совместимый | |
| i) necessity | |||||
| 1) | поверхность | 2) | преимущество | 3) необходимость | 4) чувство |
| j) to vary | |||||
| 1) | изменяться | 2) | записывать | 3) позволять себе | 4) вызывать |
| Упражнение 29.Cлову из левого столбика подберите перевод из | |||||
| правого столбика: | |||||
| a) surface | 1) делать необходимым | ||||
| b) sensible | 2) стирать | ||||
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| c) to necessitate | 3) | поверхность |
| d) various | 4) вход | |
| e) to erase | 5) | дорожка |
| f) to insert | 6) | позволить себе |
| g) track | 7) | вставить |
| h) flexible | 8) | разумный |
| i) entry | 9) гибкий | |
| j) to afford | 10) различный |
Упражнение 30. Прочитайте текст, обращая внимание на термино - логию и постарайтесь кратко объяснить, что такое гибкий диск:
Floppies
Technical Details
Information stored in the RAM is lost when the computer is turned off. Because of this data and applications are stored in the either hard or floppy disk which provide a more permanent backing store.
Floppy disks are so called because they consist of flexible plastic material which has a magnetizable surface. Sizes vary, but 3.5-inch diameter disk is the most popular.
The surface of a floppy disk is divided into concentric circles or ‘ tracks ’ which are then divided into ‘ sectors ’. When you insert a blank disk into a disk drive, it must be ‘ initialized ’, or ‘ formatted ’, before information can be recorded onto it. This means that magnetic areas are created for each track and sector, along with a catalogue or ‘ directory ’ which will record the specific location of files.
When you save a file, the operating system moves the read/write heads of the disk drive towards empty sectors, records the data and writes an entry for the directory. Later on, when you open that file, the operating system looks for its entry in the directory on the disk, moves the read/write heads to the correct sectors, and reads the file into the RAM area.
(E.C.U.)
Упражнение 31. Подберите синонимы или объяснения (правая ко - лонка) данным терминам (левая колонка):
1. backing store a) a catalogue where each piece of data is stored;
| 2. floppies | b) recording heads; | |
| 3. disk drive | c) secondary memory; | |
| 4. formatting | d) diskettes | |
| 5. | directory | e) initializing; setting tracks and sectors on magnetic |
| disks; | ||
| 6. | read/write heads | f) a peripheral which spins disks and contains a read/ |
| write head. |
Упражнение 32.
a) Прежде, чем читать текст, постарайтесь ответить на следующие
вопросы:
1. What is the main function of a hard disk?
2. Which unit is used to measure hard disk capacity?
3. Can you think of one advantage that hard disks have over floppies?
b) Прочитайте текст. Правильно ли Вы ответили?
Hard Drives
When Buying a Hard Disk
Hard disks have important advantages over floppy disks: they spin at a higher speed, so you can store and retrieve information much faster than with floppies. They can also hold vast amounts of information. Apart from this, both types of disks work in the same way. To access directly the necessary information, the read/write heads of rigid disks seek the required tracks and sectors, and then transfer the information to the main memory of the computer or to another form of storage, all of which is done in a few milliseconds (ms).
Bearing in mind that you always need disk storage, it is good sense to ask yourself some virtual questions: What size of capacity do I need? What speed can I use? What kind of storage device is the most suitable for my requirements? If only use word -processing programs you will need less storage capacity than if you use CAD, sound and animation programs.
Now let’s turn our attention to speed. Access times vary from 10 ms to 28 ms. ‘ Access time ’ – or seek time – is the time it takes read/write heads to find any particular record. You have to distinguish clearly between seek time (e.g. 20 ms) and ‘ data transfer rate ’ (the average speed required to transmit data from a disk system to the RAM). Remember that the transfer rate depends also on the power of your computer.
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When buying a hard disk you should consider the kinds of drive mechanisms and products available. There are ‘ internal ’ and ‘ external ’ drives which are both fixed hard drives, i.e. rigid disks sealed into the drive unit, either within or attached to the computer. A third type of hard drive, known as ‘ removable ’, allows information to be recorded on ‘ cartridge ’, which can be removed and stored off-line for security purposes.
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Finally, a few words about ‘ optical ’ technology: erasable optical disks and CD-ROM drives are gaining popularity very quickly. Unlike the magnetic hard disk, the CD-ROM disk (which is optical) is not used for personal data storage but for recording huge amounts of information such as a dictionary or encyclopedia.
(E.C.U.)
c) Верны ли данные утверждения?
1. Hard disks are rigid rotating disks.
2. ‘Seek time’ refers to the average time required for the recording heads to move and access data.
3. If you use multimedia applications you need the same storage capacity as required for word processors.
4. ‘Access time’ and ‘data transfer rate’ mean the same.
5. Optical disks are magnetic.
6. Removable cartridges are not transportable.
7. CD-ROM disks are used for storage of massive amounts of information.
d) Прочитайте текст еще раз и перечислите технические характери - стики, на которые Вы должны обратить внимание при покупке жесткого диска.
Упражнение 33. Суммируя информацию текстов и Ваш собствен - ный опыт и знания, сравните жесткий диск, дискету и компакт - диск, от - метьте достоинства и недостатки, постарайтесь привести убедительные аргументы.
УСТРОЙСТВА ВВОДА И ВЫВОДА
| Active Vocabulary | ||||
| to alter | flat | to print | to revolve | |
| alternative | to flatten | fingerprint | revolution | |
| to generate | printer | to rotate | ||
| arrow | printing | |||
| arrow keys | generation | to produce | rotation | |
| to hold (held) | to scan | |||
| bar | production | |||
| to master | productive | scanner | ||
| blank | productivity | handheld scanner | ||
| blank space | to paste | to realize | flatbed scanner | |
| to describe | skill | |||
| to point | to represent | |||
| description | skillful/skilful | |||
| point | representation | to slide | ||
| to distort | pointer | representative | ||
| distortion | result | slide | ||
| to drag | to result from | |||
| drag & drop | to result in | |||
| Упражнение 34.Выберите правильный перевод: | ||||
| a) arrow | ||||
| 1) мастерство | 2) стрелка | 3) искажение | 4) скольжение | |
| b) to master | ||||
| 1) вращаться | 2) овладевать | 3) заканчиваться (ч-л) 4) скользить | ||
| с) skillful | ||||
| 1) представительный 2) опытный | 3) плоский | 4) эффективный | ||
| d) to slide | ||||
| 1) вращаться | 2) овладевать | 3) заканчиваться (ч-л) 4) скользить | ||
| e) distortion | ||||
| 1) мастерство | 2) стрелка | 3) искажение | 4) скольжение | |
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| f) to result in | |||||||
| 1) | вращаться | 2) | овладевать | 3) | заканчиваться(ч-л) | 4) | скользить |
| g) to revolve | |||||||
| 1) | вращаться | 2) | овладевать | 3) | заканчиваться(ч-л) | 4) | скользить |
Упражнение 35. Слову из левого столбика подберите перевод из правого столбика:
| a) skill | 1) | заканчиваться(ч-л) |
| b) to generate | 2) | искажать |
| c) blank | 3) производить | |
| d) to distort | 4) оборот | |
| e) representative | 5) | овладевать |
| f) to master | 6) | представитель |
| g) to result (in) | 7) | свободное место |
| h) arrow | 8) | происходить в результате(ч-л) |
| i) revolution | 9) | мастерство |
| j) to result (from) | 10) стрелка |
Упражнение 36.
a) Прочитайте предложения и переведите их:
• The computer hardware can best be described as actual parts that go together to make up the computer.
• A scanner was such a costly piece of equipment that it was difficult to justify buying one for anything except an absolute need.
• Using a hand scanner is something of a skill.
б) Прочитайте текст и объясните выделенные курсивом термины:
Defining the terms
Terms that are often used when people talk about computers are hardware, software and peripherals.
The computer hardware can best be described as actual parts that go together to make up the computer such as wires, switches, electronic circuits, microprocessors and anything else that is involved in the working parts.
Software refers to the programs that are input into the computer. Disksand cassettes are often referred to as a software once they have computer programs on them but they are really peripherals.
The peripherals of the computer are the devices for input, output or storageof data and include the keyboard, visual display unit (VDU), cassettes, disk drives and printers. The VDU is also known as the monitor and the program and the results of the processing can be seen on this, as well as data entered. The printer will produce the print-out of the results of the processing. This is often referred to as hard copy.
(С. S.)
Input
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