FUNDAMENTAL OF CMPUTER

INTRODUCTION  OF  COMPUTER

The word computer is derived from the word compute. Compute means to calculate. The computer was originally defined as a super fast calculator. It had the capacity to solve complex arithmetic and scientific problems at very high speed. But nowadays in addition to handling complex arithmetic computations, computers perform many other tasks like accepting, sorting, selecting, moving, comparing various types of information. They also perform arithmetic and logical operations on alphabetic, numeric and other types of information. This information provided by the user to the computer is data. 
                           The information in one form which is presented to the computer is the input information or input data.
                                          Information in another form is presented by the computer after performing a process on it. This information is the output information or output data.
                                                                                                                      The set of instructions given to the computer to perform various operations is called as the computer program. The process of converting the input data into the required output form with the help of the computer program is called as data processing.

WHAT IS COMPUTER 

C-  Commonly

O-  Operated

M-  Machine

P-   Particularly

U-   Used for

T-   Technology

E-   Education and

R-   Research

                                          Therefore a computer can now be defined as a fast and accurate data processing system that accepts data, performs various operations on the data, has the capability to store the data and produce the results on the basis of detailed step by step instructions given to it..

 The terms hardware and software are almost always used in connection with the computer

• The Hardware :-  The hardware is the machinery itself. It is made up of the physical parts or devices of the computer system like the electronic Integrated Circuits (ICs), magnetic storage media and other mechanical devices like input devices, output devices etc. All these various hardware are linked together to form an effective functional unit. The various types of hardware used in the computers, has evolved from vacuum tubes of the first generation to Ultra Large Scale Integrated Circuits of the present generation.

STRUCTURE OF COMPUTER  HARDWARE

1. MONITOR :- A monitor is a piece of computer hardware that displays the video and graphics information generated by a connected computer through the computer's video card.

Monitors are similar to TVs but usually display information at a much higher resolution. Also unlike televisions, monitors typically sit atop a desk rather than being mounted on a wall. A monitor is sometimes referred to as a screen, display, video display, video display terminal, video display unit, or video screen.

2.MODEM :- Modem is short for "Modulator-Demodulator." It is a hardware component that allows a computer or another device, such as a router or switch, to connect to the Internet. It converts or "modulates" an analog signal from a telephone or cable wire to digital data (1s and 0s) that a computer can recognize. Similarly, it converts digital data from a computer or other device into an analog signal that can be sent over standard telephone lines.

3. C.P.U  (central processing unit) :- Stands for "Central Processing Unit." The CPU is the primary component of a computer that processes instructions. It runs the operating system and applications, constantly receiving input from the user or active software programs. It processes the data and produces output, which may stored by an application or displayed on the screen.

4. MOUSE :- The mouse, sometimes called a pointer, is a hand-operated input device used to manipulate objects on a computer screen.

Whether the mouse uses a laser or ball, or is wired or wireless, a movement detected from the mouse sends instructions to the computer to move the cursor on the screen in order to interact with files, windows, and other software elements.

Even though the mouse is a peripheral device that sits outside the main computer housing, it's an essential piece of computer hardware in most systems... at least non-touch ones.

5. SPEAKER  :- A device that converts analog audio signals into the equivalent air vibrations in order to make audible sound. When CRT monitors were the norm, speakers designed for computers were shielded to avoid magnetic interference with the CRT's magnetic coil.

6. PRINTER :- A printer is an external hardware output device that takes the electronic data stored on a computer or other device and generates a hard copy of it. For example, if you created a report on your computer, you could print several copies to hand out at a staff meeting. Printers are one of the most popular computer peripherals and are commonly used to print text and photos.

 7. KEYBOARD :- A computer keyboard is one of the primary input devices used with a computer. Similar to an electric typewriter, a keyboard is composed of buttons that create letters, numbers, and symbols, as well as perform other functions. The following sections provide more in-depth information and answers to some of the more frequently asked questions about the keyboard.

• The Software:-  The computer hardware itself is not capable of doing anything on its own. It has to be given explicit instructions to perform the specific task. The computer program is the one which controls the processing activities of the computer. The computer thus functions according to the instructions written in the program. Software mainly consists of these computer programs, procedures and other documentation used in the operation of a computer system. Software is a collection of programs which utilize and enhance the capability of the hardware.

SOME IMPORTANT KEY IN KEYBOARD

• CRUSOR CONTROL KEY :- Cursor control keys are buttons on a computer keyboard that move the cursor. They are often considered to be synonymous with arrow keys, but there is a slight difference; the cursor keys are usually several keys that can be used for the movement of the cursor, like the WASD combination. However, the arrow keys are four keys that have arrow markings on them, but are exclusively used for cursor movement in specified directions.
• CAPS LOCK KEY :- Caps Lock is a toggle key on a computer keyboard that causes all letters typed to be in uppercase until disabled. For example, when Caps Lock is enabled, the typed letters appear "LIKE THIS." When disabled, they appear "like this." The picture shows keyboard LEDs that indicate whether or not the various toggle keys are enabled. In this example, the blue LED indicates that Caps Lock enabled.
• SHIFT KEY :- The Shift key is a keyboard modifier key that allows a user to type a single capital letter and change the top number keys to a symbol. For example, pressing and holding the Shift key while pressing "a" generate a capital "A" and pressing the Shift and the number "1" creates an exclamation mark on US keyboards.
• BACK SPACE KEY:- The Backspace key or Back space key is a keyboard key that deletes any character before the cursor's current position or the left.
• DELETE KEY :- In general, delete or remove refers to the act of eliminating a file, text, or another object from the computer hard drive or other media. For example, if you had a picture on the computer you no longer wanted, it could be deleted.
• ENTER KEY  :- Alternatively known as a Return key, with a keyboard, the Enter key sends the cursor to the next line or executes a command or operation. Most full-sized PC keyboards have two Enter keys; one above the right Shift key and another on the bottom right of the numeric keypad.
•  SPACE BAR KEY :- space and the space key, the spacebar or space bar is a long horizontal key on the lower edge of a keyboard. It's always the largest and longest key on the keyboard. When the spacebar key is pressed, it creates an empty space, also known as a space character or whitespace that helps separate words and other characters in a sentences. For example, if there were not spaces in this paragraph, all of the text would be together and very difficult to read.

Characteristic of a Computer

1. SPEED :- As you know computer can work very fast. It takes only few seconds for calculations that we take hours to complete. You will be surprised to know that computer can perform millions (1,000,000) of instructions and even more per second.

2. ACCURACY :- The degree of accuracy of computer is very high and every calculation is performed with the same accuracy. The accuracy level is 7.

3. DILLIGENCE :- A computer is free from tiredness, lack of concentration, fatigue, etc. It can work for hours without creating any error. If millions of calculations are to be performed, a computer will perform every calculation with the same accuracy. Due to this capability it overpowers human being in routine type of work. 

4. VERSATILITY :- It means the capacity to perform completely different type of work. You may use your computer to prepare payroll slips. Next moment you may use it for inventory management or to prepare electric bills.

5. POWER OF REMEMBERING :- Computer has the power of storing any amount of information or data. Any information can be stored and recalled as long as you require it, for any numbers of years. It depends entirely upon you how much data you want to store in a computer and when to lose or retrieve these data. 

6. NO IQ  :- Computer is a dumb machine and it cannot do any work without instruction from the user. It performs the instructions at tremendous speed and with accuracy. It is you to decide what you want to do and in what sequence. So a computer cannot take its own decision as you can. 

7.  NO FELLING :-  It does not have feelings or emotion, taste, knowledge and experience. Thus it does not get tired even after long hours of work. It does not distinguish between users.

8. STROAGE :- The Computer has an in-built memory where it can store a large amount of data. You can also store data in secondary storage devices such as floppies, which can be kept outside your computer and can be carried to other computers. 

WHAT IS COMPUTER SYSTEM

computer system is a collection of entities(hardware,software and liveware) that are designed to receive, process, manage and present information in a meaningful format.

COMPONENTS OF COMPUTER SYSTEM

• Computer hardware - Are physical parts/ intangible parts of a computer. e.g Input devices, output devices, central processing unit and storage devices
• Computer software - also known as programs or applications. They are classified into two classes namely - system software and application software.
• User - user is the computer user. Also known as vaporware the human ware. The user commands the computer system to execute on instructions.

a) COMPUTER HARDWARE

Hardware refers to the physical, tangible computer equipment and devices, which provide support for major functions such as input, processing (internal storage, computation and control), output, secondary storage (for data and programs), and communication.

HARDWARE CATEGORIES AND THEIR FUNCTION PARTS

A computer system is a set of integrated devices that input, output, process, and store data and information. Computer systems are currently built around at least one digital processing device. There are five main hardware components in a computer system: Input, Processing, Storage, Output and Communication devices.

INPUT DEVICES

Are devices used for entering data or instructions to the central processing unit. Are classifies according to the method they use to enter data.

a) KEYING DEVICES

i) The keyboard

Keyboard similar to a typewriter is the main input device of a computer . It contains three types of keys-- alphanumeric keys, special keys and function keys. Alphanumeric keys are used to type all alphabets, numbers and special symbols like $, %, @, A etc. Special keys such as <Shift>, <Ctrl>, <Alt>, <Home>, <Scroll Lock> etc. are used for special functions. Function keys such as <Fl>, <F2>, <F3> etc. are used to give special commands depending upon the software used e.g.F5 reloads a page of an internet browser. The function of each and every key can be well understood only after working on a PC. When any key is pressed, an electronic signal is produced. This signal is detected by a keyboard encoder that sends a binary code corresponding to the key pressed to the CPU. There are many types of keyboards but 101 keys keyboard is the most popular one.

The keys on your keyboard can be divided into several groups based on function:

• Typing (alphanumeric) keys.:- These keys include the same letter, number, punctuation, and symbol keys found on a traditional typewriter.
• Special (Control) keys. :-These keys are used alone or in combination with other keys to perform certain actions. The most frequently used control keys are CTRL, ALT, the Windows key, and ESC.
• Function keys.:- The function keys are used to perform specific tasks. They are labelled as F1, F2, F3, and so on, up to F12. The functionality of these keys differs from program to program.
• Cursor Movement (Navigation) keys.:- These keys are used for moving around in documents or Web Pages and editing text. They include the arrow keys, HOME, END, PAGE UP, PAGE DOWN, DELETE, and INSERT and ARROW KEYS.
• Numeric keypad.:- The numeric keypad is handy for entering numbers quickly. The keys are grouped together in a block like a conventional calculator or adding machine.

B. POINTING DEVICESpointing devices that enter data and instructions into the computer using a pointer that appears on the screen. The items to be entered are selected by either pointing to or clicking on them.e.g mice, joystick, touch sensitive screen, trackballs

i) THE MOUSE
A mouse is a small device used to point to and select items on your computer screen.  It's small, oblong, and connected to the system unit by a long wire that resembles a tail and the connector which can either be PS/2 or USB. Some newer mice are wireless.

 A mouse usually has two buttons:

                 a primary button (usually the left button) and 

                 a secondary button(usually the right button) 

                 Many mouse also have a wheel between the two buttons,

( which allows you to scroll smoothly through screens of information.)

There are four basic ways to use your mouse buttons: clicking, double-clicking, right-clicking, and dragging.

Clicking (single-clicking)

To click an item, point to the item on the screen, and then press and release the primary button (usually the left button).

Double-clicking

To double-click an item, point to the item on the screen, and then click twice quickly. If the two clicks are spaced too far apart, they might be interpreted as two individual clicks rather than as one double-click.

Double-clicking is most often used to open items on your desktop. For example, you can start a program or open a folder by double-clicking its icon on the desktop.

Right-clicking

To right-click an item, point to the item on the screen, and then press and release the secondary button (usually the right button).

Right-clicking an item usually displays a list of things you can do with the item. For example, when you right-click the Recycle Bin on your desktop, Windows displays a menu allowing you to open it, empty it, delete it, or see its properties. If you are unsure of what to do with something, right-click it.

Data:-

Data can be defined as a representation of facts, concepts, or instructions in a formalized manner, which should be suitable for communication, interpretation, or processing by human or electronic machine.

Data is represented with the help of characters such as alphabets (A-Z, a-z), digits (0-9) or special characters (+,-,/,*,<,>,= etc.)

What is Information?

Information is organized or classified data, which has some meaningful values for the receiver. Information is the processed data on which decisions and actions are based.

For the decision to be meaningful, the processed data must qualify for the following characteristics −

• Timely − Information should be available when required.
• Accuracy − Information should be accurate.
• Completeness − Information should be complete.
• Data Processing Cycle
• Data processing is the re-structuring or re-ordering of data by people or machine to increase their usefulness and add values for a particular purpose. Data processing consists of the following basic steps - input, processing, and output. These three steps constitute the data processing cycle.
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• Input − In this step, the input data is prepared in some convenient form for processing. The form will depend on the processing machine. For example, when electronic computers are used, the input data can be recorded on any one of the several types of input medium, such as magnetic disks, tapes, and so on.
• Processing − In this step, the input data is changed to produce data in a more useful form. For example, pay-checks can be calculated from the time cards, or a summary of sales for the month can be calculated from the sales orders.
• Output − At this stage, the result of the proceeding processing step is collected. The particular form of the output data depends on the use of the data. For example, output data may be pay-checks for employees.

Pocessorr (CPU)

A processor (CPU) is the logic circuitry that responds to and processes the basic instructions that drive a computer. The CPU is seen as the main and most crucial integrated circuitry (I C) chip in a computer, as it is responsible for interpreting most of computers commands. CPU will perform most basic arithmetic, logic and I/O operations, as well as allocate commands for other chips and components running in a computer.

Processors can be found in PCs, smartphones, tablets and other computers. The two main competitors in the processor market are Intel and AMD.

The basic elements of a processor

• The arithmetic logic unit (ALU), which carries out arithmetic and logic operationson the operands in instructions. 
• The floating point unit (FPU), also known as a math co-processor or numeric coprocessor, a specialized coprocessorthat manipulates numbers more quickly than the basic microprocessor circuitry can.
• Registers, which hold instructions and other data. Registers supply operands to the ALU and store the results of operations.
• L1 and L2cache memory. Their inclusion in the CPU saves time compared to having to get data from random access memory (RAM).

Components and how CPUs work

The main components of a CPU are the ALU, registers and control unit. The basic functions of the ALU and register are labeled in the above “basic elements of a processor section.” The control unit is what operates the fetching and execution of instructions.

The processor in a personal computer or embedded in small devices is often called a microprocessor. That term means that the processor's elements are contained in a single IC chip. Some computers will operate using a multi-core processor—a chip containing more than one CPU. A CPU is typically a small device with pins on it facing down in a motherboard. CPUs can also be attached to a motherboard with a heat sink and a fan to dissipate heat.  

Memory

A memory is just like a human brain. It is used to store data and instructions. Computer memory is the storage space in the computer, where data is to be processed and instructions required for processing are stored. The memory is divided into large number of small parts called cells. Each location or cell has a unique address, which varies from zero to memory size minus one. For example, if the computer has 64k words, then this memory unit has 64 * 1024 = 65536 memory locations. The address of these locations varies from 0 to 65535.

Memory is primarily of three types −

• 1. Cache Memory
• 2. Primary Memory/Main Memory
• 3. Secondary Memory

1. Cache Memory

Cache memory is a very high speed semiconductor memory which can speed up the CPU. It acts as a buffer between the CPU and the main memory. It is used to hold those parts of data and program which are most frequently used by the CPU. The parts of data and programs are transferred from the disk to cache memory by the operating system, from where the CPU can access them.

Advantages

The advantages of cache memory are as follows −

• a.   Cache memory is faster than main memory.
• b.   It consumes less access time as compared to main memory.
• c.   It stores the program that can be executed within a short period of time.
• d.   It stores data for temporary use.

Disadvantages

The disadvantages of cache memory are as follows −

• a.   Cache memory has limited capacity.
• b.   It is very expensive.

2. Primary Memory (Main Memory)

Primary memory holds only those data and instructions on which the computer is currently working. It has a limited capacity and data is lost when power is switched off. It is generally made up of semiconductor device. These memories are not as fast as registers. The data and instruction required to be processed resides in the main memory. It is divided into two subcategories RAM and ROM.

Characteristics of Main Memory

• a.   These are semiconductor memories.
• b.    It is known as the main memory.
• c.    Usually volatile memory.
• d.    Data is lost in case power is switched off.
• e.    It is the working memory of the computer.
• f.     Faster than secondary memories.
• g.    A computer cannot run without the primary memory.

3. Secondary Memory (Aixiliary Memory)

This type of memory is also known as external memory or non-volatile. It is slower than the main memory. These are used for storing data/information permanently. CPU directly does not access these memories, instead they are accessed via input-output routines. The contents of secondary memories are first transferred to the main memory, and then the CPU can access it. For example, disk, CD-ROM, DVD, etc.

Characteristics of Secondary Memory

• a.    These are magnetic and optical memories.
• b.    It is known as the backup memory.
• c.     It is a non-volatile memory.
• d..    Data is permanently stored even if power is switched off.
• e.    It is used for storage of data in a computer.
• f.     Computer may run without the secondary memory.
• g.    Slower than primary memories.

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