Dr. Himanshu Gupta Senior Faculty MemberAIIT, AMITY University, Noida.

Fundamental of Computers

• A computer can convert data into information that is useful to people.

• A complete computer system includes four distinct parts:

Hardware

Software

Data

User

What is a Computer?

A computer is an electronic device used to process data.

• A computer's hardware consists of electronic devices; the parts you can see and touch.

• The term "device" refers to any piece of hardware used by the computer, such as a keyboard, monitor, modem, mouse, etc.

Hardware

• Software – also called programs – consists of organized sets of instructions for controlling the computer.

• Some programs exist for the computer's use, to help it manage its own tasks and devices.

• Other programs exist for the user, and enable the computer to perform tasks for you, such as creating documents.

Software

• Data consists of raw facts, which the computer can manipulate and process into information that is useful to people.

• Computerized data is digital, meaning that it has been reduced to digits, or numbers. The computer stores and reads all data as numbers.

• Although computers use data in digital form, they convert data into forms that people can understand, such as text, numerals, sounds, and images.

Data

• People are the computer's operators, or users.

• Some types of computers can operate without much intervention from people, but personal computers are designed specifically for use by people.

Users

Computer Architecture

• Types of Hardware

• The CPU

• Memory

• How Memory is Measured

• Input and Output Devices

• Storage Devices

A computer's hardware devices are categorized as follows:

• Processor

• Memory

• Input and output (I/O) devices

• Storage devices

Types of Hardware

0100101001101010

011011111000111110000000

CPU

The procedure that transforms raw data into useful information is called processing. This function is divided between the computer's processor and memory.

The processor is also called the central processing unit (CPU). It manages all devices and performs the actual processing of data.

The CPU consists of one or more chips attached to the computer's main circuit board (the motherboard).

• Memory also consists of chips attached to the motherboard.

• Memory holds data and program instructions as the CPU works with them. This memory is called Random Access Memory (RAM).

• The CPU can find any piece of datain RAM, when it needs it for processing.

• RAM is volatile, meaning it holds dataonly when the power is on. When the poweris off, RAM's contents are lost.

Memory

• The smallest usable unit of measure for memory is the byte – the amount of memory required to hold one character, like the letter A or the numeral 2.

• Computers work with larger chunks of data, measured in multiple bytes, as shown below:

Unit Approx. Value Actual Value (bytes) (bytes)

Kilobyte (KB) 1,000 1,024 Megabyte (MB) 1,000,000 1,048,576Gigabyte (GB) 1,000,000,000 1,073,741,824Terabyte (TB) 1,000,000,000,000 1,099,511,627,776

How Memory is Measured

• Input devices accept data and instructions from the user or from another computer system. The keyboard and mouse are examples of input devices.

• Output devices return processed data back to the user or to another computer system. The printer and monitor are examples.

• Communications devices (such as modems and network interface cards) perform both input and output, allowing computers to share information.

Input and Output Devices

• Storage devices hold data not currently being used by the CPU. Data is commonly stored on a magnetic or optical disk. Each type uses a special medium for storing data on its surface.

• A disk drive is a device that reads data from and writes data to a disk. Most new computers feature a floppy disk drive, a hard disk drive, and an optical disk drive.

• The most common optical storage devices are CD-ROM and DVD-ROM drives.

Storage Devices

Software

• Software is a set of electronic instructions that tells the computer how to do certain tasks. A set of instructions is often called a program.

• When a computer is using a particular program, it is said to be running or executing the program.

• The two most common types of programs are system software and application software.

• System software exists primarily for the computer itself, to help the computer perform specific functions.

• One major type of system software is the operating system (OS). All computers require an operating system.

• The OS tells the computer how to interact with the user and its own devices.

• Common operating systems include Windows, the

Macintosh OS, OS/2, and UNIX .

System Software

• Application software tells the computer how to accomplish tasks the user requires, such as creating a document or editing a graphic image.

• Some important kinds of application software are:

Word processing programs Spreadsheet softwareDatabase management Presentation programsGraphics programs Networking software Web design tools and browsers Internet applicationsCommunications programs UtilitiesEntertainment and education Multimedia authoring

Applications Software

Computer Classif ications

Super Computers

Mainframe Computers

Mini Computers

Workstation

Micro Computers (PC)

• Binary Numbers

• The Binary Number System

• Bits and Bytes

• Text Codes

How Computers Represent Data

Binary Numbers

• Computer processing is performed by transistors, which are switches with only two possible states: on and off.

• All computer data is converted to a series of binary numbers– 1 and 0. For example, you see a sentence as a collection of letters, but the computer sees each letter as a collection of 1s and 0s.

• If a transistor is assigned a value of 1, it is on. If it has a value of 0, it is off. A computer's transistors can be switched on and off millions of times each second.

Base 10 Base 2

0 0

1 1

2 10

3 11

4 100

5 101

6 110

7 111

8 1000

9 1001

10 1010

• To convert data into strings of numbers, computers use the binary number system.

• Humans use the decimal system (“deci” stands for “ten”).

• The binary number system works the same way as the decimal system, but has only two available symbols (0 and 1) rather than ten (0, 1, 2, 3, 4, 5, 6, 7, 8, and 9).

The Binary Number System

• A single unit of data is called a bit, having a value of 1 or 0.

• Computers work with collections of bits, grouping them to represent larger pieces of data, such as letters of the alphabet.

• Eight bits make up one byte. A byte is the amount of memory needed to store one alphanumeric character.

• With one byte, the computer can represent one of 256 different symbols or characters.

.

How Computers Represent Data - Bits and Bytes

1 0 1 1 0 0 1 01 0 0 1 0 0 1 01 0 0 1 0 0 1 11 1 1 1 1 1 1 1

• A text code is a system that uses binary numbers (1s and 0s) to represent characters understood by humans (letters and numerals).

• An early text code system, called EBCDIC, uses eight-

bit codes, but is used primarily in older mainframe systems.

• In the most common text-code set, ASCII, each character consists of eight bits (one byte) of data. ASCII is used in nearly all personal computers.

• In the Unicode text-code set, each character consists of 16 bits (two bytes) of data.

How Computers Represent Data - Text Codes

Code Character

00110000 0

00110001 1

00110010 2

00110011 3

00110100 4

00110101 5

01000001 A

01000010 B

01000011 C

01000100 D

01000101 E

Examples from theASCII Text Code

Where Processing Occurs:

• The Control Unit

• The Arithmetic Logic Unit

• Machine Cycles

• The Role of Memory in Processing

• Types of RAM

How Computers Process Data

• Processing takes place in the PC's central processing unit (CPU).

• The system's memory also plays a crucial role in processing data.

• Both the CPU and memory are attached to the system's motherboard, which connects all the computer's devices together, enabling them to communicate.

CPU

The two main parts of a CPU are the control unit and the arithmetic logic unit (ALU)

• The control unit directs the flow of data through the CPU, and to and from other devices.

• The control unit stores the CPU's microcode, which contains the instructions for all the tasks the CPU can perform.

The Control Unit

• The actual manipulation of data takes place in the ALU.

• The ALU can perform arithmetic and logic operations.

• The ALU is connected to a set of registers—small memory areas in the CPU, which hold data and program instructions while they are being processed.

The Arithmetic Logic Unit

Arithmetic Operations

LogicalOperations

+ Add = , ≠ equal to, not equal to

− Subtract >, > greater than, not greater than

x Multiply <, < less than, not less than

÷ Divide ≥ , ≥ greater than or equal to,

not greater than or equal to

^ Raise by a power ≤ , ≤ less than or equal to,

not less than or equal to

ALU Operations List

• RAM stores data and program code needed by the CPU. The contents of RAM change rapidly and often.

• Read-only memory (ROM) is nonvolatile (or permanent). It holds instructions that run the computer when the power is first turned on.

• The CPU accesses each location in memory by using a unique number, called the memory address.

Memory

There are two basic types of RAM: static and dynamic

• Dynamic RAM (DRAM) chips must be recharged with electricity very frequently, or they will lose their contents.

• Static RAM (SRAM) does not need to be rechargedas often as DRAM, and can hold its contents longer.

Another type of RAM, called flash memory, can store its contents after power is turned off. Flash memory is used in digital cameras to store pictures.

Types of RAM

More RAM = Better Performance!

• Cache memory is high-speed memory that holds the most recent data and instructions that have been loaded by the CPU.

• Cache is located directly on the CPU or between the CPU and RAM, making it faster than normal RAM.

• CPU-resident cache is called Level-1 (L1) cache. External cache is called Level-2 (L2) cache.

• The amount of cache memory has a tremendous impact on the computer's speed.

Cache Memory

• The operating system manages all the other programs that run on the PC.

• The operating system provides services to programs and the user, including file management, memory management, and printing

• To provide services to programs, the OS makes system calls—requesting other hardware and software resources to perform tasks.

Operating system

• Multitasking is the capability of running multiple processes simultaneously.

• A multitasking OS lets you run multiple programs at the same time.

• Through multitasking, you can do several chores at one time, such as printing a document while downloading a file from the Internet.

• There are two types of multitasking: cooperative and preemptive.

Operating System - Multitasking

• The operating system keeps track of all the files on each disk.

• Users can make file management easier by creating a hierarchical file system that includes folders and subfolders arranged in a logical order.

Operating System - Managing Files

• The OS uses interrupt requests (IRQs) to maintain organized communication with the CPU and other pieces of hardware.

• Each hardware device is controlled by a piece of software, called a driver, which allows the OS to activate and use the device.

• The operating system provides the software necessary to link computers and form a network.

Operating system - Managing Hardware

• Graphical User Interfaces (GUIs)

• Command-Line Interfaces

The User Interface

• Most modern operating systems, like Windows and the Macintosh OS, provide a graphical user interface (GUI).

• A GUI lets you control the system by using a mouse to click graphical objects on screen.

• A GUI is based on the desktop metaphor. Graphical objects appear on a background (the desktop), representing resources you can use.

Graphical User Interfaces (GUIs)

Icons

Start menu

Start button

Taskbar

Desktop

Dialog box

Programrunning ina window

Window control buttons

• Some older operating systems, such as DOS and UNIX, use command-line interfaces.

• In a command-line interface, you type commands at a prompt.

• Under command-line interfaces, individual applications do not need to look or function the same way, so different programs can look very different

. Command-Line Interfaces

• The Difference between Databases and DBMSes

• Database Basics

• DBMSes Basics

Databases and Database Management Systems

• A database is a repository for collections of related data or facts.

• A database management system (DBMS) is a software tool that lets users add, view, and work with the data in a database.

• Large databases and DBMS’ are commonly used by companies, but many productivity applications are built around database concepts.

The Difference between Databases and DBMSes

The two primary types of databases are flat-file databases (with only one table) and relational databases (with multiple, related tables).

• Fields, which store various pieces of data related to a single entity.

• Records, or collections of fields relating to an entity.

• Tables, which are collections of related records.

Databases use three main structures for organizing data:

Databases and DBMSes - Database Basics

Field

Record

Table

PROFESSIONAL ADDRESS BOOK

• Entering data into the database.

• Sorting (rearranging) the data in the database.

• Obtaining subsets of the data for use.

A DBMS allows users to access and manage the data collected in a database.

Data management tasks (all done through the DBMS) can be divided into three categories:

Databases and DBMSes - DBMS Basics

• Simultaneous Access

• Shared Peripheral Devices

• Personal Communication

A network connects computers so they can communicate, exchange information, and share resources.

The main benefits of using a network are:

Computer Network

• In organizations, many people may need to use the same data or programs. A network solves this problem.

• Shared data and programs can be stored on a central network server. A server that stores data files may be called a file server.

• Managers may assign access rights to users. Some users may only be able to read data, others may be able to make changes to existing files.

The Uses of a Network - Simultaneous Access

• Because peripheral (external) devices like printers can be expensive, it is cost-effective to connect a device to a network so users can share it.

• Through a process called spooling, users can send multiple documents (called print jobs) to a networked printer at the same time. The documents are temporarily stored on the server and printed in turn.

The Uses of a Network -Shared Peripheral Devices

• One of the most common uses of networks is for electronic mail (e-mail).

• An e-mail system enables users to exchange written messages (often with data files attached) across the local network or over the Internet.

• Two other popular network-based communications systems are teleconferencing and videoconferencing.

The Uses of a Network - Personal Communication

1 2 3 4

• A LAN is a network whose computers are located relatively near one another. The nodes may be connected by a cable, infrared link, or small transmitters.

• A network transmits data among computers by breaking it into small pieces, called packets.

• Every LAN uses a protocol – a set of rules that governs how packets are configured and transmitted.

Type of Networks – Local Area Networks (LANs)

• Multiple LANs can be connected together using devices such as bridges, routers, or gateways, which enable them to share data.

• A WAN is two or more LANs connected together. The LANs can be many miles apart.

• To cover great distances, WANs may transmit data over leased high-speed phone lines or wireless links such as satellites.

Type of Networks – Wide Area Networks (WANs)

LAN 1

WAN

LAN 2

Type Aheader

Payload Type Aheader

Payload

Type Aheader

Payload

Significantgeographical

distance

ROUTER ROUTER

SERVER SERVER

• In client/server computing, individual nodes share the processing and storage workload with the server.

• Client/server networks require specialized software that enables nodes and the server to collaborate on processing and storage, but no special type of network hardware.

Networks Structure – Cl ient/Server Networks

1

2

3

• In a peer-to-peer network, all nodes have an equal relation to one another.

• Each node usually has access to some resources on other nodes, so users can share files, programs, or devices on other users' systems.

• Some peer-to-peer networks use a server, but some do not.

Networks Structure – Peer-to-Peer Networks

• Bus. Each node is connected in series along a single conduit.

• Star. All nodes are connected to a central hub.

• Ring. Nodes are connected in a circular chain, with the conduit beginning and ending at the same computer.

• Mesh. Each node has a separate connection to every other node.

A network's topology is the layout of the cables and devices that connect the nodes. The four most common network topologies are:

Network Topologies for LANs

• In a network, the media are the wires, cables and other means by which data travels from its source to its destination.

• The most common network media are twisted-pair cable, coaxial cable, fiber-optic cable, and wireless links.

• Each node uses a special device, called a network interface card (NIC). The card connects to the network media and controls the flow of data.

• NICs must use a common network technology to communicate. The most popular network technologies for LANs are Ethernet, Fast Ethernet, and Token Ring.

Network Media and Hardware

• Word processors provide tools for creating, editing, and formatting text-based documents.

• You can use a word processor to create virtually any type of document, from a simple letter to a complete book.

• A word processor's formatting tools let you create professional-quality documents easily.

Word Processing Programs and Their Uses

Word processors provide tools to produceprofessional looking documents.

• Document area

• Menu bar

• Toolbars

• Rulers

• Scroll Bars

• Status Bar

Most Windows-based word processors offer a similar set of tools, which you use to navigate, edit, and format documents:

The Word Processor 's Interface

Menu bar Toolbars

Ruler

Document areaStatus bar

Scroll barScroll boxes

• Spreadsheets provide tools for working with numerical data.

• You can use a spreadsheet program to create budgets, balance sheets, and other types of number-based documents.

• You can display your information in a traditional row-and-column format, or in a chart.

Spreadsheet Programs and Their Uses

Classic row and column format

Report usingcolor and graphics

• In a spreadsheet program, you work in a document called a worksheet. You can collect multiple worksheets into a file called a workbook.

• Most Windows-based word spreadsheets offer a similar set of tools, including a formula bar, where you can enter and edit data.

• Data is displayed in cells. A cell is the intersection of a row and column.

• Each cell has a cell address – the combination of the cell's column letter and row number.

The Spreadsheet 's Interface

Menu barTool bars

Column

Row

Status bar

Scroll boxes

CellFormula bar