Study of Computer Components, accessories, practice of important DOS Commands

 

Various Components of Computer

 

 

CPU

Its meaning is Central Processing Unit. Sometimes referred to simply as the central

processor or Nerve Centre or heart, but more commonly called processor, the CPU is where most calculations take place. The CPU is the brains of the computer.

Central processing unit (CPU) is the central component of the Computer System. Sometimes it is called as microprocessor or processor. It is the brain that runs the show inside the Computer. All functions and processes that is done on a computer is performed directly or indirectly by the processor. Obviously, computer processor is one of the most important elements of the Computer system. CPU is consists of transistors, that receives inputs and produces output. Transistors perform logical operations which is called processing. It is also, scientifically, not only one of the most amazing parts of the PC, but one of the most amazing devices in the world of technology.

In terms of computing power, the computer processor is the most important element of a computer system. It add and compare its data in cpu chip. A CPU of all computers, whether micro, mini or mainframe must have three parts.

Parts of CPU

Arithmetic Logic Unit (ALU): It is the part of computer processor (CPU) can be used to perform arithmetic and logic operations. An arithmetic-logic unit (ALU) is further divided into two parts, (AU) arithmetic unit and a (LU) logic unit.

Control Unit (CU): Decodes the program instruction. CPU chip used in a computer is partially made out of Silica. on other words silicon chip used for data processing are called Micro Processor.

Keyboard

A computer keyboard is an input device used to enter characters and functions into the computer system by pressing buttons, or keys. It is the primary device used to enter text. A keyboard typically contains keys for individual letters, numbers and special characters, as well as keys for specific functions. A keyboard is connected to a computer system using a cable or a wireless connection.

 

Typical keyboard for a desktop computer

 

Most keyboards have a very similar layout. The individual keys for letters, numbers and special characters are collectively called the character keys. The layout of these keys is derived from the original layout of keys on a typewriter. The most widely used layout in the English language is called QWERTY, named after the sequence of the first six letters from the top left.

 

 

Mouse

A computer mouse is a handheld hardware input device that controls a cursor in a GUI and can move and select text, icons, files, and folders. For desktop computers, the mouse is placed on a

flat surface such as a mouse pad or a desk and is placed in front of your computer. The picture to the right is an example of a desktop computer mouse with two buttons and a wheel.

 

 

The mouse was originally known as the X-Y Position Indicator for a Display System and was invented by Douglas Engelbart in 1963 while working at Xerox PARC. However, due to Alto's lack of success, the first widely used application of the mouse was with the Apple Lisa computer. Today, this pointing device is on virtually every computer.

 

Monitor

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.

 

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.

 

 

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.

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.

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.

 

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.

 

Storage Devices

1.   USB Flash Drive

A USB Flash Drive is a small, ultra-portable storage device which is used to store data and transfer information. Flash drives are also called as pen-drives, jump-drives, and thumb-drives. Basically, every USB flash drive are re-writable and removable. Actually, USB Flash Drive is robust because there are no moving parts. At the time of First stage the size of USB Flash Drive was just like 8 MB and now the size of USB Flash Drive is just like 2 GB to 1 TB.

 

 

 

 

 

 

2.   Memory Cards

A Memory Card is a small storage device just like 16 MB to 64 GB and this storage device is used for storing media and data files. Memory card is Non-Volatile, permanent storage device which is used inside of Phone, Camera, and many other electronic devices. There are so many types of memory card in market, and it's totally depended on size.

 

 

3.   CD (Compact Disk)

The CD was created by Pilips factory in Germany on august,1982. Compact Disk is the full form of CD, it‘s looks like a flat, round and the measures of standard CD is 120 millimeters and across

1.2 mm thick. The size of Compact Disk is 650 Megabytes to 700 Megabytes. A compact Disk is a portable storage medium that can store audio, video, picture, and also Data.

 

 

 

4.   DVD (Digital Video Disk)

DVD (Digital Video Disk) is an optical disk format invented and developed in 1995.The Capacity of CD is 4.7 GB and the Weight is 16 grams. The Compact Disk can store any kind of digital media just like video, audio, picture, game, software, data. Actually, DVD is just like a ROM because data can only be read and not written. DVD can be single side or double side both, the size of single side DVD is 4.7 GB and the size of double side DVD is 9.4 GB.

5.  HDD (Hard Disk Drive)

 

IBM company‘s engineer created the first Hard Disk Drive in 1953.The size of Hard Disk was just like two refrigerators. A Hard Disk Drive is a non-volatile secondary storage device, here data can store permanently. unlike RAM, it is non-volatile means data is retained when the computer is turned off. A Hard Disk Drive is actually a set of stacked disks. The first production IBM hard Disk was 305 disk storage which was shipped in 1957.