Home Random Page


CATEGORIES:

BiologyChemistryConstructionCultureEcologyEconomyElectronicsFinanceGeographyHistoryInformaticsLawMathematicsMechanicsMedicineOtherPedagogyPhilosophyPhysicsPolicyPsychologySociologySportTourism






ELEMENTS OF HARDWARE

 

Output

The two most popular output devices are the printer and the video screen, or monitor. A monitor is required for almost any computer system for two reasons. First, the data or instructions being input from the keyboard or other input device are shown on the monitor. A blinking rectangle or underline called a cursor moves on the screen as the data or instructions are input. Second, the monitor is an almost instantaneous outlet for the result of the processing.

Often a user will view the results of processing on the monitor screen and then decide that hard copy is needed, in the form of a printed page. Such hard copy is useful because the output to the monitor is not permanent. For main­frame users, it is usually very easy to divert the output on the monitor to a page printer at a computer center. A page printer is a high-speed printer that can print an entire page in one motion. For personal computer users, a large number of printers are available today in varying speeds, qualities of print, and price ranges. Other types of printers commonly used with PCs are ink jet printers and laser printers. The ink-jet printer sprays ink on the page to create letters and pictures. The laser printer is much like a copier except that instead of photocopying an existing document, it converts output from a computer into a printed form.

Input/Output Telecommunication

The most popular devices that facilitate both input and output and allow computers to communicate are network adapter and modem.

A network adapter is a computer hardware component designed to allow computers to communicate over a computer network. It enables physical access to a networking medium and provides a low-level addressing system by means of MAC addresses.

Modem sends and receives information between computers over telephone lines. The modem con­verts the electrical signals from RAM in the computer into the type of electrical signals that can travel over telephone lines. In other words, the digital output from the computer must be modulated into an analog form before it can be sent over a telephone line, and the analog input received over the telephone line must be demodulated into digital form before it can be used for input into the computer.

The term modem is used because the device MOdulates/DEModulates sig­nals. With a modem, a computer terminal or a personal computer can be used to communicate with a mainframe or another personal computer. In either case, the modem acts as both an input device and an output device so the computer can send and receive information over the telephone lines. This is very useful for persons who wish to work at home, access a computerized information ser­vice to research some topic, or simply communicate with other computer users.

 

Text B


Date: 2015-02-03; view: 819


<== previous page | next page ==>
HELP FOR NURSES FROM HELPMATE | THE FIRST COMPUTER
doclecture.net - lectures - 2014-2024 year. Copyright infringement or personal data (0.007 sec.)