keyboard

keyboard

keyboard:

Programs and data are entered into a computer through a key-board which is attached to a computer. A keyboard is similar to the keyboard of a typewriter. It contains alphabets, digits, special characters, function keys and some control keys. When a key is pressed, an electronic signal is produced which is detected by an electronic circuit called keyboard encoder . A computer includes all the keys found on a typewriter plus some additional keys. These additional keys are cursor control (i.e. moving the cursor around on the screen), insert, delete, and scroll control keys. There are a total of 101 keys (some have more). At the right side of the keyboard is the numeric keypad with numbers and basic mathematical symbols. 

keyboard daigram

    Numeric keypad can also be used for cursor control. This double function of numeric keypad is controlled by ( Num Lock ) key. 

The keyboard contains a small built-in processor. When you pre a key, the keyboard processor detects it and sends a number (binary nurnber) corresponding to that key (scan code) to the key-board cotitlIcr, located on the motherboard. This code is then finally transmitted to the processor (CPU). The CPU then processes it using a program called keyboard driver. The keyboard driver translates the codes into their corresponding characters. Different types of keys ind their functions are described in the following Sections.

    Standard Typewriter kays:

PC keyboard has a set of keys that closely resemble the keys found on a typewriter. These include the numeric keys (0 to 9), character keys (A to Z), special characters (!, @, #, $, etc.). These keys are often called QWERTY keys (named after the top row of letters).

    Function Keys:

Keys labelled as F1 to F12 carry out special functions in the soft-ware running in the PC. For example, the F1 key in most pro-grams displays the help file available for using that program.

   Cursor Movernenf Keys:

These ←, →, ↑, ↓arrow keys are used to move a cursor (a blinking line on the tivelyonitor) to the left, right, up or down respectively. In addition, there are four more keys, PGUP, PGDOWN, HOME, and END. This keys let you move the cursor quick throught text. The HOME and END keys are specially used for positioning the cursor at the 101 keys model of the keyboard, there is a separate set of cursor movement keys, namely ←, →, ↑, ↓ arrow keys. But in the case of old type 83 keys model of the key-board, you\need to press ( Num lock) key to change over between the numeric and cursor movement functions of the keys. 

Computer organization (cpu)

What is Computer Organization:

The internal arrangement of different parts of a computer is called the computer organization. It differs from one computer system to another. However, the basic organization remains the same for all types of computer systems.

              All computer systems perform the following five basic operations.

1. Inputting
2. Storing Processing
3. Outputting
4. Controlling

Computers receive most data from either the keyboard, scanner, mouse or disk. Information is saved on a floppy disk or hard disk. Data is manipulated or processed by the processors and the resulting output is either displayed on a monitor or printed on paper.

A block diagram of the basic computer organization is shown in figure 2.1. It depicts the five major building blocks, of functional units of a digital computer system. These five units correspond to the five basic operations performed by all computer system. The function of each of these units is described in subsequent sections.

CENTRAL PROCESSING UNIT (CPU):

The Central Processing Unit (CPU) is the brain of any computer system. In a human body, all major decisions are taken by the brain and all other parts of the body function as directed by the brain. Similarly, in a computer system, all major calculation, manipulations and comparisons are made by the CPU. The CPU is also responsible for activating and controlling the operations performed by all other unites of the computer system.

              The major pares of a CPU are:

(a)    Arithmetic and Logic unit (ALU)

(b)    Control unit (CU)

(c)     Main Memory of Primary Memory

Arithmetic and Logic unit (ALU):

All calculations are performed and all comparisons (dicisions) are made in the ALU. The data and instructions, stored on the primary memory prior to processing and manipulation of data is done in the Arithmetic and Logical Unit.

Intermediate results generated in the ALU are temporarily transferred back to the primary memory until needed again. After completions of processing, the final results available in the primary memory are sent to an output device. Such as monitor.

ALUs are designed to perform the four basic arithmetic operations- add, subtract, multiply, didide- and logic operations or comparisons such as less than, equal to, or greater than. Figure2.2 shows different operations of the computer system from the layman’s point of view.

In this figure, the calculator as a part of ALU represent the central processing Unit and the clock carries out the control function for different operations of the keyboard input and the monitor output. This figure gives more of a conceptual working of the digital computer. The actual block diagram representation, containing the jobs done by each part is shown in Figure 2.1.

Control unit:

How does the input device know that it is it is time for it to feet data into the storage unit? How dos the input device know that it is time for it to feed data into the storage unit? How does the ALU know what should be done with the data once the received? And how it is possible because of the control unit of the computer system. By selecting, instruction, the control unit is able to maintain order and direct the working of the entire computer system. Although it does not perform any processing on the data, the control unit acts as the central nervous system for all other components of the computer. It coordinates the entire computer system.

Types of Computer

TYPES OF COMPUTERS:

Computers are classified into many categories depending upon their size, functioning and processing capabilities.

1. According to how it functions, computers can be classified into three categories:

Analog Compute

            A. Analog: According to the Merriam Webster Dictionary, computers in which continuously variable physical quantities, such as electrical potential, fluid pressure, or mechanical motion, are used to represent (analogously) the quantities in the problem to be solved are called analog computers. 

Digital Computer

            B.Digital: These computers deal with data in the form of numbers. They mainly operate by counting and performing arithmetic & logical operations on numeric data. Such computers are ‘many problems’ oriented.

            

   C. Hybrid:

Hybrid Computer

Digital computers could not deal with very large numbers and so, a computer with characteristics of both analog and digital was created which was known as Hybrid computer

2. According to the size, computers are classified into the following categories:

A. PERSONAL COMPUTER:

The most common types of computer is personal  computer- a personal computer that is designed to sit on  a desk or table. These are the systems you see all  around you, in school, homes, and office.

Personal Computer

 Today’s personal computers are more  powerful than                 those of just a few year’s ago. Not only do  these                     machine enable people to do their jobs with  greater                 ease and efficient, but they can be used to                                  communicate, produce music, edit photographs                         and  videos, etc. the main components of the                               

personal  computer is the system units.

B. MAINFRAME COMPUTER:

Mainframe computer

    Mainframe computers can also process data at very high speeds, but less than thatof super computers. Normally, they are used in banking, airlines and railways etc. for their applications

                    B.  Mini Computer:

  Mini computers provide more power than micro    computers in terms of speed and storage   capacity. They are also less expensive. Their performance is also lower than that of  mainframes.

                    C. MICRO COMPUTER:

 Microcomputers are designed to be used by single user for performing basic operations like educational activities, playing games. These are mainly used in homes, offices, shops, school etc. 

                   D.  SUPER COMPUTER:

Super Computer

A supercomputer is the fastest type of computer. They are employed for specialized applications that require large amounts of mathematical calculations. A supercomputer channels all its power into executing a few programs at great speed, whereas a mainframe uses its power to execute many programs at the same time. These computers are used to solve problems involving quantum mechanical physics, weather forecasting, climate research, molecular modelling such as computing the structures and properties of chemical compounds, simulations, cryptanalysis, and many others.

 Parts of Computer: 

Any kind of computers consists of HARDWARE AND SOFTWARE. 

Hardware: 

Computer hardware is the collection of physical elements that constitutes a computer system. Computer hardware refers to the physical parts or components of a computer such as the monitor, mouse, keyboard, computer data storage, hard drive disk (HDD), system unit (graphic cards, sound cards, memory, motherboard and chips), etc. all of which are physical objects that can be touched.

parts of Hardware

Example of computer HARDWARE:

1. KEYBORD
2. MOUSE
3. CPU
4. MOTHER BOARD
5. MONITER

Software:

Software is a generic term for organized collections of computer data and instructions, often broken into two major categories: system software that provides the basic non-task-specific functions of the computer, and application software which is used by users to accomplish specific tasks.

Software Types:

A. System software:

System software is responsible for controlling, integrating, and managing the individual hardware components of a computer system so that other software and the users of the system see it as a functional unit without having to be concerned with the low-level details such as transferring data from memory to disk, or rendering text onto a display. Generally, system software consists of an operating system and some fundamental utilities such as disk formatters, file managers, display managers, text editors, user authentication (login) and management tools, and networking and device control software.

B. Application software:

Application Software is used to accomplish specific tasks other than just running the computer system. Application software may consist of a single program, such as an image viewer; a small collection of programs (often called a software package) that work closely together to accomplish a task, such as a spreadsheet or text processing system; a larger collection (often called a software suite) of related but independent programs and packages that have a common user interface or shared data format, such as Microsoft Office, which consists of closely integrated word processor, spreadsheet, database, etc.; or a software system, such as a database management system, which is a collection of fundamental programs that may provide some service to a variety of other independent applications.

Comparison Application Software and System Software:

System Software:

Computer software, or just software is a general term primarily used for digitally stored data such as computer programs and other kinds of information read and written by computers. App comes under computer software though it has a wide scope now.

Example:

1) Microsoft Windows
2) Linux
3) Unix
4) Mac OSX
5) DOS

Interaction:

Generally, users do not interact with system software as it works in the background.

Dependency:

System software can run independently of the application software.

Application Software:

Application software, also known as an application or an "app", is computer software designed to help the user to perform specific tasks.

Example:

1) Opera (Web Browser)

2) Microsoft Word (Word Processing)

3) Microsoft Excel (Spreadsheet software)

4) MySQL (Database Software)

5) Microsoft PowerPoint (Presentation Soft

Interaction:

Users always interact with application software while doing different activities.

Dependency:

Application software cannot run without the presence of the system software.

Characteristics of Computer

 Characteristics of Computer 

Speed, accuracy, diligence, storage capability and versatility are some of the key characteristics of a computer. A brief overview of these characteristics are 

• Speed:

 The computer can process data very fast, at the rate of millions of instructions per second. Some calculations that would have taken hours and days to complete otherwise, can be completed in a few seconds using the computer. For example, calculation and generation of salary slips of thousands of employees of an organization, weather forecasting that requires analysis of a large amount of data related to temperature, pressure and humidity of various places, etc. 

• Accuracy: 

Computer provides a high degree of accuracy. For example, the computer can accurately give the result of division of any two numbers up to 10 decimal places. 

• Diligence: 

When used for a longer period of time, the computer does not get tired or fatigued. It can perform long and complex calculations with the same speed and accuracy from the start till the end. 

• Storage Capability: 

 Large volumes of data and information can be stored in the computer and also retrieved whenever required. A limited amount of data can be stored, temporarily, in the primary memory. Secondary storage devices like floppy disk and compact disk can store a large amount of data permanently. 

• Versatility:

Computer is versatile in nature. It can perform different types of tasks with the same ease. At one moment you can use the computer to prepare a letter document and in the next moment you may play music or print a document. Computers have several limitations too. Computer can only perform tasks that it has been programmed to do.

Introduction of computer

Introduction of Computer:-

A computer is a programmable machine designed to perform arithmetic and logical operations  automatically and sequentially on the input given by the user and gives the desired output after

 processing. Computer components are divided into two major categories namely hardware and

software. Hardware is the machine itself and its connected devices such as monitor, keyboard, 

mouse etc. Software arethe set of programs that make use of hardware for performing various 

functions.

Functionalities of a computer:-

Any digital computer carries out four functions in gross terms they are:

• Takes data as input.
• Stores the data/instruction in its memory and use them when required.
• Processes the data and converts it into usefull information.
• Generates the Output.

• 

  processing of computer