FUNDAMENTAL PART II

On line auxiliary storage device

When the storage device is online with the processor it is said to be on line storage device e.g. Hard Disk.

Off line auxiliary storage device

            Storage device not directly on line with the processor are know as off line storage device e.g. Floppy diskette, Magnetic Tape etc.

Auxiliary memory stores information and data which may be transferred to and from the main memory while processing and when needed as per programmed. It is virtually higher in capacity and less expensive than main memory, but retrieving time is more than main memory.

Arithmetic Logic Unit (ALU)

            Ii derives data from main memory, performs arithmetic and logic operations, and places intermediate results in worming storage area of main memory further, results are fed to output storage of main memory for further feeding the data/information to output devices. Typical arithmetic operations may be +,–,* and/ (where * stands for multiplication and /stands for division). Similarly, logic operation may be AND, OR, NOT and EXCLUSIVE OR. The operation of control Unit and ALU are performed at very high speed with the help of electrical logic gates or electronic circuits.

Busbar system

In fact the busses are conductor lines etched or the printed Circuits boards (PCB) usually motherboard along which data which data travels from one part to another. There are three main kinds of buses:

–        Address Busto carry address or memory location through the Control Unit to ALU and back.

–        Data bus to carry data/information from memory chip to CPU and back.

–        Control bus to carry control signals to enire CPU, perihpherals, input/output devices etc.

We may summarise function of these buses in to system bus peripheral bus

                              System Bus :-            It connects CPU and memory.

                              Peripheral Bus :-      It connects CPU with other peripherals.

PERIPHERALS

Peripheral Controllers

      Peripheral controllers or interface device are usually printed Circuit Board(PCB).hardware or daughter boards which control, interpret and coordinate the activities of peripheral devices by providing path for the movement of data/control signals between peripheral devices and CPU. Peripheral devices and CPU. Peripheral controllers are usually connected to the motherboards at one end and respective peripherals at the other end e.g. CTD controller, FDD controller, HDD controller etc.

All input, output and auxiliary storage devices (i.e. other than CPU) are known as peripherals. These may be divided in to:

                              a. Input Devices                                b. Output Devices

                              c. Interactive Devices                      d. Storage Devices

                              e. Data Entry Machines

                                   -On-line Data Entry Machines

                                   -Off-line Data Entry Machines

Input Devices

Devices used for communication from humans to computers which reads data instructions, converts them in to machine readable form and inputs them to computer are said to be input devices.

There are two types of input devices.

      On-line input devices

      Off-line input devices

On-line input devices

      Input devices which are directly connected to the processor are said to be on-line input devices e.g. Keyboard, mouse, touch screen etc.

Off-line input devices

      Input devices which are not directly connected to the processor are said to be off-line input devices. There devices allow to record data on medium e.g magnetic tape, floppy diskettes etc.

Output Devices

      There are devices to communicate from computers to human beings or to other computers. They accept machine coded output from CPU and convert it into formats understandable to human beings to other machines for further processing e.g. printers, VDU magnetic tape, floppies etc.

Interactive device

      Devices which helps users to communicate directly with computers Processors are said to be interactive devices e.g. Automated Teller Machines, cash Dispensers, touch screen devices etc.

Storage devices

            Devices which store the data are said to be storage devices e.g. magnetic tape, floppy, compact disk, cartridge tape etc.

Data Entry Machines

      These machines are used to entry data in to computers through input/inter-active devices.

On-line Data Entry Machines are directly connected with the CPU of computer.

On-line workstations are also example of On-line data entry machines.

Off-line Data entry Machines are directly connected with the CPU of computer. Stand alone or independent personal Computers, palm top / Lap top computers can also be used an Off-line data entry machine other than from such machines

Power Supply Unit

      Computer also needs electric power to operationally its parts and accessories, or it will idle like other familiar appliances which need electric. Power e.g. radio, television,. refrigerator, audio systems etc. there is slight difference in the power need of supply of computers because they need specific current, voltage for various circuits for specific operations. They also need a steady power supply which is usually provided through Voltage Stabilizer or Constant Voltage Transformer (CVT). A part from external (and optional) devices that provide constant as well as stable electric supply e.g.. Voltage stabilizer, CVT etc. it has a built-in Power supply unit Known as Switch Mode power Supply (SMPS) unit. It provides necessary current/ voltage to different part of computers with necessary safety precaution arrangements.

All of the above components are synchronized by system’s clock which emits number of pulses per second. That is why the speed of microprocessor is related to its clock speed in Mega Hertz. Also size or power of CPU is determined by data bus size i.e. 8-bit, 16-bit, 32-bit, 64 bit etc.

I am sure that you are able to outline a typical computer system which may be summarized by following block diagram:

 

How if logical explanation elaborated above are illustrated with an example of typical Personal Computer along with Peripheral devices.

Understanding Personal Computers

A computer based on microprocessor as the central Processing Unit (CPU) usually targed to the information processing needs of a individual is known as Personal Computer.

You might have heard terms such as PC, PC-XT, PC-ATs etc

Microprocessor :- A Microprocessor executes all the program instruction and is truly the heart of the personal computer. It consists of a silicon clip on which tiny circuit are engraved through a photochemical processor. Such as :- P1, P2, P3, P4

Evolution of Intel’s Microprocessor Chips

Year	1979	1982	1985	1986	1993	1993 on/wards
Microprocessor chip	8088	80286	80386	80486	Pentium	Pentium Pro
Bits	16 Bits	16 Bits	32 Bits	32 Bits	32 Bits	32 Bits
Transistors	28,000	1,34,000	2,75,000	1,200,000	3,000,000	6,000,000
Clock Speed	5 MHz	8MHz	8 MHz	25 MHz	25 MHz Upgradable upto 120 MHz	200 MHz
MIPS	0.33 MIPS	1.2	6	20	44	250 to 300 MHz

GREEN PC

Some manufacture have designed and developed the computer hardware components environment friendly in view to save power when the system is on but not in use. Basic features of green pc include display power management, disk shut off. Clock switching to lower frequencies. When the system is on but not in use simultaneously cutting down running costs.

            Till now we have studied about the internal Anatomy of a personal computer. Now, let us share some information about external anatomy of a pc known as peripherals that surrounds the processor and memory.

Peripherals may be classified as under:

·        Input devices.

·        Output devices

·        Mass Storage devices

·        Interactive devices

·        Data communication equipments (DCEs)/ Cards/Interfaces

Input Devices

Devices which are used to transform data into digital into digital codes understandable to computers are known as input devices. Input process may be also transformed or direct input from the source. In transforming process the data is transformed from source documents to another media or directly to computer for processing e.g Keyboard touch screen. In direct input from source process, the data is captured directly from source documents without transforming with the help of any techniques/devices e.g. scanner, MICR, voice input etc.

Keyboard

            Keyboard is the most common input device which is not only used on a PC but also used Telephone, Cash Register, FAX, Telex, Typewriter etc. Keyboard being used in computer are generally contain electromechanical key switches or membrane keyboard having flat sealed surface. It is almost impossible to interact with a computer without keyboards.

This keyboard may be either build in build or detached. Most general purpose keyboards are typewriter like standard QWERTY keyboards and have the keys Q W E R T Y......in the top row of alphabets. Now bilingual keyboards are also available in Indian market which helped us to use the same for working in Hindi as well as. English.

Here add Picture of Keyboard

Function of some special keys of a slandered 101-Keys-AT Keyboard is as under:

1.      Escape (Ese) :- Its function is based on application program and differs from program to program. Usually, it is used to interrupt printing, operating moving from one mode to another or escaping from current processing job.

2.      Control & Alternate: - It is also based on application program and always used in conjunction with one or two other keys to perform some pre-determined functions. User has to hold down Ctrl or Alt key with other pre-programmed/defined keys.

3.      Print Screen/Sys Req :- It sends output of screen to printer. If printer does not support bit mapped graphics and screen contains graphics, the output printer will be a rough approximation.

4.      Scroll Lock - It pause a program's operation or interrupts scrolling.

5.      Pause/Break- It pauses or break/spots the running of a program.

6.      Caps Lock & Shift :- It toggles all alphabetical keys from Upper to lower and vice-versa leaving all non alphabetical keys uncharged. Page Up, Page Down, Home, End, Ins, Del key keys of other set are digits from 0 to 9 with duplicate cursor keys, NumLock, =,/*,-,+. And enter key.

7.      Insert - It toggle keyboard function between insert mode and normal mode. In normal mode character right to the cursor moves one space right of the cursor while keying. In insert mode character are overwritten on previously typed matter.

8.      Home: - It brings cursor at the top of monitor screen or line or file.

9.      End - It brings cursor at the end of the screen or line or file.

10. Page Up & Page Down – Page Up scrolls upward screen at a time Page Down scrolls downward a screen at a time while editing. These keys are also activated with combination of Ctrl and Alt keys.

11. Delete :- It erases character lies under the cursor. It also erases character right to the cursor speedily when held down.

12. Back Space:- It moves the cursor to the left while erasing character in its path.

13. Return or Enter- It usually performs two functions. It instructs computer to executed command just entered and brings cursor at the beginning of the next line providing one carriage return.

How it works?

 Whenever a user presses any key on keyboard the device translates the key stroke into the equivalent binary code or key stroke is encoded. The encoded strings of 'ons' or '1s' or '0s' and sent to computer from keyboard. Computer sends the encoded strings to monitor to represent the pressed key's character and shifts one space right. The diagram is self explicit.

The above diagram explains that on pressing key 'A' a string of equivalent binary '10100001' is sent to monitor through system unit for displaying character A.

POINTING DEVICES

      Pointing devices are peripherals used for moving pointer/cursor/ object on display screen and interacting with computer such as mice, joystick, track ball, touch, screen etc, Most of the pointing devices are based on touch technology. Some important pointing devices are discussed below.

TRACK BALL ROLLERS

 These track ball rollers are in fact upside down mice. The track ball roller device can be placed at any convenient surface or can be fixed on keyboard. This device became very useful for Note Book/Laptop Personal Computers. It also needs special track ball roller driver program.

MOUSE

      Mouse is an input device which controls the cursor and move the any file from one place to other place.

Mouse can be further divided into four types:-

1.      Normal Mouse

2.      Scroll Moue

3.      Optical Mouse

4.      Cordless Mouse

Normal Mouse:- In normal mouse to used ball roller for moving the mouse pointer one place to another place.

Left button :-  From this button we can select of any program which is represent inside the computer system.

Click:- Whenever You can press the left/right button of mouse on any function is called click.

1.      Single click :- Whenever you can select of any file and program them click at a one times are known as single click.

2.      Double click:- Whenever you can load/open of any folder or file and program then use to double press of it key are called as double click.

3.      Triple click:- Whenever you can select of any word/contain then press triple times of it key are known as triple click.

Right click:- From this button to you gets of details information to related any folder or file act like show the properties of any type documents.

Such as:- When you right click on the desktop screen under this located the following command  in the pop up menu.

Scroll Mouse:- It is type of mouse. In this mouse to used for moving the mouse pointer as ball roller and distinguish to add scroll button between left and right button.

Use of scroll button:-  It button is use for scrolling of page from left to right and up to down.

Optical Mouse:- It is types of mouse. In this mouse to used for moving of mouse pointer as laser light.

Wireless Mouse:- this type of mouse but dot not used in  wire to connected from CPU.

JOY STRICKS

It is a device that fits into contours of user's hands enabling user to use various buttons to control movement of cursor/pointing/objects on the monitor screen. The shapes and size of joy sticks differs from hardware to hardware and games loaded on the system. Mostly this device is useful for video/computer games.

TOUCH SCREENS

It is the best way to make your personal computer interactive. In fact the human finger is the most common and natural pointing device which has been used as an input device for interacting with computers. In this technique user operates or activates menus or gives command by touching monitor screen at specified place. It is the most convenient pointing device. The major drawback in this technique is that user becomes tired due to continuous operation and also the screen becomes dirty due to continuous touch.

How it works?

There are basically two methods to convert the screen as touch sensitive.

a.      Infra-red Light

b.      Overlaying

Infra-red light- The entire monitor screen is crisscrossed with invisible infra red beams which are sensed by photo detectors and other side when user touches any point of screen it interrupts vertical and horizontal invisible beams and help user to select/activate the loaded computer program.

Overlaying:- In this technique the monitor screen is overplayed with a thin layer of placed having sensing grids built into it. When user touches at any point of the monitor screen the predetermined option is selected to activate concerned program.

Aslo according to the software loaded user can freehand draw or sketch on the screen.

Light Pen

You will accept that it is quite difficult pinpoint on monitor screen with human finger. Light pen device has rectified this drawback. It is similar to that of a pen that could be placed at any point on screen and can be used to draw accurately than human finger.

Touch/Digitiser Tablet

Touch/ Digititer tablet function as a touch screen. These are also known touch pads or digitizer pads. These are easy and convenient to use because we are habitual to write on horizontal surface rather than on vertical surface such as monitor screen.

Scanners

This is photo copier shaped device wihch converts text or graphics images into digital images that can be processed (capture, crop, resize, retouch etc.) by computers. These processed images can be further used in multimedia application such Desk Top Publishing (DTP), Video Animation, Slides for advertisement/teaching etc. These digital image files can aslo be stored and communicated through e-mail, fax, mdem etc.

How it works?

A beam of light passes across document or object which is read by means of photo sensing device. The sensor of photo sensing device senses and differentiates lighter and darker areas then translates the intensity digitally into 1s and 0s with the help of Analog to Digital Converter (ADC) circuits representing black, write and gray shades. The scanner must pass three times over the object for colour scanning for three basic primary colour; red, green and blue to form the final digital coloured image. All scanner software. Let us share some information about various scanners and their working.

There are four types of scanner:

a. Handheld scanner :- It fits into palm. It can be held in hand and sided over document also steady hand.

b. Flatbed Scanner :- It is quite similar to the shape of photo copier. The document is either placed facing down on glass plate or fed through bin stacker.

c. 3-D Scanner :- The object to be scanned is placed at a pre requisite place and scanned from overhead camera or camera mounted on adjustable copy stand with light on moreover side. The distance from camera is adjusted according to magnification level and range of coverage of the apperture of lence of array type 3-D scanners. Other scannners have cammeras at fixed distance from the object.

d. Film Scanner:- The slide or negative or photo films are inserted in scanner and focus is adjusted to set the desired resolution, size colours etc.

OCR ( OPTICAL CHARACTER RECOGNITION)

            Optical Character Recognition (OCR) is the technique that scans the text or printed image of document with the help of scanner, reads the symbols and transcribe them into computer readable format. The OCR software does this tremendous job of direct data entry from the source document readable format. The OCR software does this tremendous job of direct data entry from the source document. This technique has helped the publishing industry to entry and manipulated the printed text for further reprinting. Now Intelligent Character Recognition software can read variety of type styles.

OMR (OPTICAL MARK RECOGNITION)

Optical Mark Recognition is the process in which assignment of values to marks placed at specific place upon the specially designed document. The marking may be done in ink pencil, typewriter etc. This method is popularly used by various recruitment/placement agencies, professional bodies, and educational establishment to evaluate multiple choice examination answer sheets.

MICR (MAGNETIC INK CHARACTER RECOGNITION)

This technique is specifically being used by banking and financial industry since its origin for handling banking instruments/documents such as cheques, drafts etc. MICR is technique permits reader to recognize human recognizable characters printed in special magnetisable ink capable of processing with related machines.