IV. Comprehension Check

1. Match the following words with their synonyms marked in the text with bold type: kept, specialized, often, look like, changing, usual (2), to input, instruction, basic.

Complete the following sentences.

1. … is probably the most widely used mechanism for entering data into a computer-usable form.

2. Terminals are often used for ….

3. … is used only to input data; it cannot do any processing on its own.

4. A smart computer is used to input data, but it also has ….

5. An intelligent computer can … as well as do its own processing.

6. Dedicated data entry systems do nothing but ….

7. … is a vital part of a computer based information system.

3. Read the text again to decide if the statements are true or false. Correct the false ones with the facts from the text.

Answer the questions.

1. What is the difference between a dumb terminal and an intelligent terminal?

2. What is the function of a dedicated data entry system?

3. What procedures might be carried out by a company to ensure data has been input accurately?

4. What kind of input device is necessary to input bar code information to the computer?

5. What are some of the current limitations of voice input technology?

6. Describe three direct-entry input devices that are being used today.

7. Describe the different types of keys on a standard microcomputer keyboard and their functions.

8. What is the purpose of a key-to-disk system?

9. What are portable terminals? Why do many business users find it necessary to use them?

10. What capabilities do executive, or integrated, workstations typically have?

V. Discuss the following with your groupmates.

Interview the manager of a store that uses point-of-sale terminals. Who manufactures the hardware? How expensive is it? What type of computer is connected to a series of POS terminals? Have the employees had any trouble using the terminals?

 

Практическое занятие №7

Тема: Устройства хранения данных.

Storage Hardware

I. First thoughts. What is storage hardware? Name the most popular pieces.

II. Study the words. Make sure you know them. Practice the pronunciation.

Field, history file, output file, parity bit, recording density, report file.

III. Read the text and do the tasks following it.

Storage and storage needs must be properly evaluated if a business is to run smoothly. The requirements for storage capacity, speed of data retrieval, size, cost, complexity of equipment, and so on, vary from business to business.

Basically there are two types of storage: primary storage (also called main memory, internal memory, or memory), where data is volatile, and secondary storage (also called auxiliary storage), where data is nonvolatile. If data is volatile, it is lost when the power to the computer is turned off; nonvolatile data remains intact.

In storage, data is represented using a binary code, a system of combinations of binary digits (bits)—0, meaning "off" (no magnetic spot present), and 1, meaning "on" (magnetic spot present). Two common binary coding schemes are the American Standard Code for Information Interchange (ASCII) and the Extended Binary Coded Decimal Interchange Code (EBCDIC). ASCII is typically used to represent data on microcomputers, and EBCDIC is used on larger computers.

Data is stored in files, which can be understood by means of the data storage hierarchy. A file is a collection of records; a record is a collection of fields, which comprise a collection of bytes. A byte, or a character, is a collection of 8 bits. A nineth bit—the parity bit—may be added as an error-checking device. Files can be categorized as follows: (1) transaction file, (2) master file, (3) report file, (4) output file, (5) history file, and (6) backup file.

The three methods used to store and retrieve data in files are: sequential, direct, and indexed sequential. In the sequential method, data can be retrieved only in the order in which it is stored. All records must be read to get to the data you want. Direct access avoids that problem by allowing you to go straight to the data you want. Key fields are used by the computer as identifiers to locate the data. The indexed sequential method allows both sequential and direct access through the use of an index set up by the computer according to key fields and locations on the storage media. Your business needs should determine the type of storage and retrieval method you use.

Introduced in the early 1950s, magnetic tape quickly overcame the limitations of punched cards as a storage medium. On magnetic tape, data is stored only in sequential fashion using either the ASCII or EBCDIC coding schemes. Unfortunately, data put on tape can't be reorganized or altered without creating a new tape. Because of their limitation, direct access storage media were developed for microcomputers, including diskettes, hard disks, hard cards, and optical disks. The direct access storage media used with the larger computers include removable disk packs, fixed disks, and disk cartridges.

Data is stored on disk surfaces in sectors and tracks. Higher track density (tracks per inch) and higher recording density (bits per inch) both result in greater amounts of data per disk. Storage capacity is measured in thousands of bytes (kilobyte—K), millions of bytes (megabyte—MB), billions of bytes (gigabyte— GB), and trillions of byte (terabyte—TB). The disk devices used on larger computers are typically capable of storing a greater amount of data in a smaller amount of space than those used for microcomputers. Microcomputer storage technology is rapidly advancing, however, so the difference in storage capacity may not last.

IV. Comprehension Check.

1. Match the following words with their synonyms marked in the text with bold type: directly, set, evaluated, manner, power-dependent, specify, changed, show, classified, pattern, lead to, removed, to find, differ.