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V. Answer the questions.

1. What is called a digital data storage device that writes and reads data via magnetization changes of a magnetic storage disk along concentric tracks?

2. To what features can the proliferation of HDD be directly attributed?

3. What is the origin of the term Winchester drive?

4. Does this term have any technical or scientific meaning?

5. How does the hard drive store data?

6. How is the mechanism for reading and writing data on a disk called?

7. What does the track recording density depend on?

8. What do hard disk drives consist of?

9. Do the heads in most hard disks touch the platters during normal operation?

11. What is a head crash and what can be the result of it?

12. How do magnetic drives operate?

13. What are the effects of electromagnetism?

14. In what is the storage capacity of hard drive measured?

15. What devices manage the flow of data to and from the hard disk?

Computer Output

Output is data that has been processed into a useful form called information that can be used by a person or a machine.

The type of output generated from the computer depends on the needs of the user and the hardware and software that are used. Two common types of output are reports and graphics. These types of output can be printed on a printer or displayed on a screen. Printed output is called hard copy and output that is displayed on a screen is called soft copy. Other types of output include audio (sound) and video (visual images).

The table below shows you the trends in output media and methods that have developed over the generations of computing.

First

Generation

Second

Generation

Third Generation

Fourth

Generation

Fifth Generation

Output

Media

Punched Cards

Printed Reports and Documents

Punched Cards

Printed Reports and Documents

Printed Reports and Documents

Video Displays

Video Displays

Audio Responses

Printed Reports and Documents

Video Displays

Voice Responses

Hyperlinked Multimedia Documents

As you can see, video displays and printed documents have been and still are the most common forms of output from computer systems.

Video displays are the most common type of computer output. Usually, the clarity of the video display depends on the type of the video monitor you use and the graphics circuit board installed in your computer. These can provide a variety of graphics modes of increasing capabilities. A high resolution, flicker-free monitor is especially important if you spend a lot of time viewing multimedia on CDs or the Web.

The research and development of higher quality monitors has led to improvements in the miniaturization of internal components, in the reduction of monitor thickness, and in the quality of picture displayable by a monitor. Accordingly, various display technologies, such as a cathode ray tube (CRT), plasma display panel (PDP), light emitting diode (LED), electroluminescent display (ELD), liquid crystal display (LCD). Electrochemical display (ECD), field emission display (FED), electrophoretic image display (EPID), and vacuum fluorescent displays (VFD), have been developed. The cathode ray tube has been used for a television or a monitor of a computer as a display device for a long time since it has a high quality and a low manufacturing cost. However, cathode ray tube monitors are heavy and bulky, and have a high power consumption and low display quality.

A liquid crystal display device has a number of advantageous features including light weight, reduced thickness and low power consumption, providing a thin, flat display. Today, CRT monitors are being replaced with compact LCD monitors that are designed using a combination of LCD and semiconductor techniques. LCD monitors have been widely applied to several portable information products, such as notebooks, PDAs, digital cameras, cell phones. The LCD monitors gradually replace the CRT monitors of the conventional desktop computers.

In a liquid crystal display, a liquid crystal is deposited between two sheets of polarizing material. When an electrical current passes between crossing wires, the liquid crystals are aligned so light cannot shine through, producing an image on the screen. Advances in technology such as active matrix and dual scan capabilities have improved the clarity of LCD displays. Active matrix LCD screens use individual transistors to control each crystal cell. Dual scan is a type of passive matrix LCD screen frequently used on lower cost portable computers.