1 COPA Practical - Identify the computer peripherals and internal parts of the computer
V E S R N TECHNOLOGIES
Input Unit This unit contains devices with the help of which we enter data into the computer. This unit creates a link between the user and the computer. The input devices translate the information into a form understandable by the computer. CPU (Central Processing Unit) CPU is considered as the brain of the computer. CPU performs all types of data processing operations. It stores data, intermediate results, and instructions (program). It controls the operation of all parts of the computer. CPU itself has the following three components − • ALU (Arithmetic Logic Unit) • Memory Unit • Control Unit Output Unit The output unit consists of devices with the help of which we get the information from the computer. This unit is a link between the computer and the users. Output devices translate the computer's output into a form understandable by the users. Central Processing Unit (CPU) consists of the following features − • CPU is considered as the brain of the computer. • CPU performs all types of data processing operations. • It stores data, intermediate results, and instructions (program). • It controls the operation of all parts of the computer. CPU itself has following three components. • Memory or Storage Unit • Control Unit • ALU(Arithmetic Logic Unit) Memory or Storage Unit This unit can store instructions, data, and intermediate results. This unit supplies information to other units of the computer when needed. It is also known as internal storage unit or the main memory or the primary storage or Random Access Memory (RAM). Its size affects speed, power, and capability. Primary memory and secondary memory are two types of memories in the computer. Functions of the memory unit are − • It stores all the data and the instructions required for processing. • It stores intermediate results of processing. • It stores the final results of processing before these results are released to an output device. • All inputs and outputs are transmitted through the main memory. Control Unit This unit controls the operations of all parts of the computer but does not carry out any actual data processing operations. Functions of this unit are − • It is responsible for controlling the transfer of data and instructions among other units of a computer. • It manages and coordinates all the units of the computer. • It obtains the instructions from the memory, interprets them, and directs the operation of the computer. • It communicates with Input/Output devices for transfer of data or results from storage. • It does not process or store data. ALU (Arithmetic Logic Unit) This unit consists of two subsections namely, • Arithmetic Section • Logic Section Arithmetic Section Function of arithmetic section is to perform arithmetic operations like addition, subtraction, multiplication, and division. All complex operations are done by making repetitive use of the above operations. Logic Section Function of logic section is to perform logic operations such as comparing, selecting, matching, and merging of data. Computer - Input Devices Following are some of the important input devices which are used in a computer ➢ Keyboard ➢ Mouse ➢ Joy Stick ➢ Light pen ➢ Track Ball ➢ Scanner ➢ Graphic Tablet ➢ Microphone ➢ Magnetic Ink Card Reader(MICR) ➢ Optical Character Reader(OCR) ➢ Bar Code Reader ➢ Optical Mark Reader(OMR) Following are some of the important output devices used in a computer. ➢ Monitors ➢ Graphic Plotter ➢ Printer Monitors Monitors, commonly called as Visual Display Unit (VDU), are the main output device of a computer. It forms images from tiny dots, called pixels that are arranged in a rectangular form. The sharpness of the image depends upon the number of pixels. There are two kinds of viewing screen used for monitors. • Cathode-Ray Tube (CRT) • Flat-Panel Display Cathode-Ray Tube (CRT) Monitor The CRT display is made up of small picture elements called pixels. The smaller the pixels, the better the image clarity or resolution. It takes more than one illuminated pixel to form a whole character, such as the letter ‘e’ in the word help. A finite number of characters can be displayed on a screen at once. The screen can be divided into a series of character boxes - fixed location on the screen where a standard character can be placed. Most screens are capable of displaying 80 characters of data horizontally and 25 lines vertically. There are some disadvantages of CRT − • Large in Size • High power consumption Flat-Panel Display Monitor The flat-panel display refers to a class of video devices that have reduced volume, weight and power requirement in comparison to the CRT. You can hang them on walls or wear them on your wrists. Current uses of flat-panel displays include calculators, video games, monitors, laptop computer, and graphics display. The flat-panel display is divided into two categories − • Emissive Displays − Emissive displays are devices that convert electrical energy into light. For example, plasma panel and LED (Light-Emitting Diodes). • Non-Emissive Displays − Non-emissive displays use optical effects to convert sunlight or light from some other source into graphics patterns. For example, LCD (Liquid-Crystal Device). Printers Printer is an output device, which is used to print information on paper. There are two types of printers − • Impact Printers • Non-Impact Printers Impact Printers Impact printers print the characters by striking them on the ribbon, which is then pressed on the paper. Characteristics of Impact Printers are the following − • Very low consumable costs • Very noisy • Useful for bulk printing due to low cost • There is physical contact with the paper to produce an image These printers are of two types − • Character printers • Line printers Character Printers Character printers are the printers which print one character at a time. These are further divided into two types: • Dot Matrix Printer(DMP) • Daisy Wheel Dot Matrix Printer In the market, one of the most popular printers is Dot Matrix Printer. These printers are popular because of their ease of printing and economical price. Each character printed is in the form of pattern of dots and head consists of a Matrix of Pins of size (5*7, 7*9, 9*7 or 9*9) which come out to form a character which is why it is called Dot Matrix Printer. Advantages • Inexpensive • Widely Used • Other language characters can be printed Disadvantages • Slow Speed • Poor Quality Daisy Wheel Head is lying on a wheel and pins corresponding to characters are like petals of Daisy (flower) which is why it is called Daisy Wheel Printer. These printers are generally used for word-processing in offices that require a few letters to be sent here and there with very nice quality. Advantages • More reliable than DMP • Better quality • Fonts of character can be easily changed Disadvantages • Slower than DMP • Noisy • More expensive than DMP Line Printers Line printers are the printers which print one line at a time. These are of two types − • Drum Printer • Chain Printer Drum Printer This printer is like a drum in shape hence it is called drum printer. The surface of the drum is divided into a number of tracks. Total tracks are equal to the size of the paper, i.e. for a paper width of 132 characters, drum will have 132 tracks. A character set is embossed on the track. Different character sets available in the market are 48 character set, 64 and 96 characters set. One rotation of drum prints one line. Drum printers are fast in speed and can print 300 to 2000 lines per minute. Advantages • Very high speed Disadvantages • Very expensive • Characters fonts cannot be changed Chain Printer In this printer, a chain of character sets is used, hence it is called Chain Printer. A standard character set may have 48, 64, or 96 characters. Advantages • Character fonts can easily be changed. • Different languages can be used with the same printer. Disadvantages • Noisy Non-impact Printers Non-impact printers print the characters without using the ribbon. These printers print a complete page at a time, thus they are also called as Page Printers. These printers are of two types − • Laser Printers • Inkjet Printers Characteristics of Non-impact Printers • Faster than impact printers • They are not noisy • High quality • Supports many fonts and different character size Laser Printers These are non-impact page printers. They use laser lights to produce the dots needed to form the characters to be printed on a page. Advantages • Very high speed • Very high quality output • Good graphics quality • Supports many fonts and different character size Disadvantages • Expensive • Cannot be used to produce multiple copies of a document in a single printing Inkjet Printers Inkjet printers are non-impact character printers based on a relatively new technology. They print characters by spraying small drops of ink onto paper. Inkjet printers produce high quality output with presentable features. They make less noise because no hammering is done and these have many styles of printing modes available. Color printing is also possible. Some models of Inkjet printers can produce multiple copies of printing also. Advantages • High quality printing • More reliable Disadvantages • Expensive as the cost per page is high • Slow as compared to laser printer