Computers Monitors

A. Monochrome Monitors: -These are Black & White monitor, green phosphors or amber monitors. They do not receive T.V signals.

B. Colour Monitors:-This monitors display is in colours. They are clearer and sharper than the monochrome monitor. There are different sizes of monitors such as “14, 15, 17, 21, etc. Now a days introduced LCD (Liquid Crystal Display) Monitors.

2)         PRINTERS: -

        For a permanent output require a printer, which is also a common output device. They are Electro-Mechanical devices, which print characters from the electrical signals sent to it by “C.P.U” The output generated by printer is called “Hard copy”. Printers can be classified into Two Categories.

I           IMPACT PRINTERS           II.        NON - IMPACT PRINTERS

I.     IMPACT PRINTERS: 

            The printers in these categories, the characters to be printed by the print head striking an inked ribbon against the paper and given sound for print.

1.         DOT MATRIX PRINTERS: 

               The characters are produced by a series of pins [normally nine], arranged vertically, which strike an inked ribbon against a paper. Each character is produced with in a pre - designed matrix of DOTS (hence the name DOT MATRIX), which is normally 9x9 dots per character. The speed range is from 120-300CPS (Character Per Second).

2.         LINE PRINTER: - 

         Line printers print complete lines, (up to 16) at a time character in width at speed range from 300-2000 LPM [Line Per Minute]. There are two types of line printers. 1. Barrel printers [Drum Printers]   

 2.            Chain printers

3.         DAISY WHEEL PRINTER:

       The character of these printers are held on wheels that resembles a daisy, hence, they are called Daisy Wheel Printers. These printers are relatively slow, there speed range from 20-80 CPM (Character Per Minute). But the quality of print is very superior other than impact printers. Another name of wheel printers is “Latter Quality Printer”. Now a days it will be can used very rare.

4.         PLOTTOR:-

        Though dot matrix printer has capabilities of producing graphic output, the resolution is quite limited. For high quality large size Diagrams, Images Graphs the graphic plotter is required. Now a days used its for Commercial Banner’s, Advertisement Boards etc’s.(Now a days used at DTP Centre for FLEXI Banner printing).

II)     NON-IMPACT PRINTERS: -

           They are more versatile and offer better quality outputs.

 1.        LASER PRINTERS: -

                  LASER is stand for “Light Amplification by Stimulated Emission of Radiation.” In this type of printer a laser beam is used to write characters on a rotating drum that is electro statistically charged. The drum generates a paper copy in a manner similar to a “Xerox” copies. These printers have high speeds, normally measured in PPM (Pages Per Minute). Typical speed of range is 30 and 60 PPM

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2)         INK JET PRINTER: 

        These printers squirt very tiny dots of ink through a nozzle, and paints images with the tiny dots.

3)         SPEAKER:

           This is also Output Device. With speaker we can listen sounds (i.e. Songs and already loaded sounds in computers).

CLASSIFICATION OF COMPUTERS

The classification of computers, based on the type of data is as follows:

I)         DIGITAL COMPUTERS: 

          These computers operate on discrete data and are commonly used in business application.  

II)        ANALOG COMPUTERS: 

            This type of computer works on continues data measured along a continues scale. For example, a speedometer is a mechanical device that works on continues data. Analog Computers are commonly used in process control systems which monitor pressure temperature, flow, etc.

III)      HYBRID COMPUTERS: 

          This type of computer combines the properties of both analog and digital computers. A typical example is found in medicine, where analog properties are used to record the patient’s data, while digital properties help in the analysis of the data as well as in monitoring the patient’s health.

Computers are also classified on the basis of their Physical Size, Memory, and Processing Speed. The important types of computers are briefly described below:

1)         MICRO COMPUTERS: - 

         Microcomputers are system based on the use of microprocessors. A microprocessor is programmable large-scale integrated circuit chip containing all the elements required to processes binary coded data.

Micro Computers manufactured by I.B.M (International Business Machines). Microcomputers are also called “Personal Computers” (Pc’s) and this is single user system. PC’s Performs all arithmetic and logical functions of a computer. The processing speed of computer measured in terms of “K I P S” (Kilo Instructions Per Seconds).