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Unit 8 storage
Part 1 Primary and Secondary Storage Units Word list:
Read the text and say what the storage device is, what types of it you read about. Computer system architecture is organized around the primary storage unit because all data and instructions used by the computer system must pass through primary storage. As you know, there are primary and secondary storage units. Both contain data and the instructions for processing the data. Primary storage is also called main storage or internal storage. The specific functions of internal storage are to hold (store): 1) all data to be processed; 2) intermediate results of processing; 3) final results of processing; 4) all the instructions required for ongoing process. Another name for primary storage is memory, because of its similarity to a function of the human brain. However, computer storage differs from human memory in important respects. Computer memory must be able to retain very large numbers of symbol combinations, without forgetting or changing any details. It must be able to locate all its contents quickly upon demand. The combinations of characters, that is, the letters, numbers, and special symbols by which we usually communicate, are coded. The codes used by a computer are based upon a number system that has only two possible values, 0 and 1. A number system with only two digits, 0 and I, is called a binary number system. Each binary digit is called a bit, from binary digit. Codes used by computer designers are based upon combinations of bits. These combinations are called binary codes. The most common binary codes are 8-bit codes. Data in the form of coded characters are stored in adjacent storage locations in main memory in two principal ways: 1) as «strings» of characters — in bytes; and 2) within fixed-size «boxes» — in words. A fixed number of consecutive bits that represent a character is called a byte. The most common byte size is 8-bit byte. Wordsare usually 1 or more bytes in length. Secondary storage. Primary storage is expensive because each bit is represented by a high-speed device, such as a semiconductor. A million bytes (that is, 8 million bits) is a large amount of primary storage. Often it is necessary to store many millions, sometimes billions, of bytes of data. Therefore slower, less expensive storage units are available for computer systems. These units are called secondary storage. Data are stored in them in the same binary codes as in main storage and are made available to main storage as needed. Exercises to the subject: I. Find English equivalents to the following words from the text: структура комп’ютерної системи; первинний пристрій пам’яті; зовнішній запам’ятовуючий пристрій; оперативна пам’ять; внутрішня пам’ять; проміжні результати; подібність функції людського мозку; розміщати вміст на вимогу; система обчислення; двійкова система обчислення; можливі величини; об’єм інформації; двійковий код; суміжні елементи пам’яті; послідовність символів; напівпровідник; доступний. II. Find the synonyms to the following words: Memory; element; information; command; examination; character; quantity; number; place; computer architect; likeness. To apply; to form; to move; to hold; to demand; to connect; to supply; to place; to name; to start; to examine. Continuous; significant; consecutive; usual; enough; main; initial; general. III. Read the text again and answer the following questions: 1. How is computer system organized? 2. What are the two main types of storage units? 3. What do they contain? 4. What is the function of a primary storage? 5. Why is primary storage often called memory? 6. In what respect does computer memory differ from human memory? 7. What are codes based on? 8. What is secondary storage and what is it used for?
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