Chapter 1

An Overview of the Computer System

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This lesson includes the following sections:

•The Computer System Defined

•Hardware: The Nuts and Bolts of the Machine

•Software: Bringing the Machine to Life

•The Shapes of Computers Today

The Computer System Defined

A computer is an electronic device used to process data, converting data into information that is useful to people.

A complete computer system includes four distinct parts:

• Hardware

• Software

• Data

• User

The Computer System Defined - Hardware:

•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

Hardware: The Nuts and Bolts of the Machine - Types of Hardware

• 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 (motherboard).

Hardware: The Nuts and Bolts of the Machine - The CPU

The Central processing Unit (CPU)

The central processing unit (CPU) contains electronic circuits that cause processing to occur.

The CPU interprets instructions to the computer, performs the logical and arithmetic processing operations, and causes the input and output operations to occur.

It is considered the “brain” of the computer.

It consists of :

1. Control unit (CU)

2. Arithmetic and Logic unit (ALU)

3. Memory unit (MU)

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The Central processing Unit (CPU) (cont.)

• Control Unit : central system controls the flow of data to and from the main storage and peripherals.

• Arithmetic and Logic Units : This unit performs arithmetic operations such as addition ,subtraction ,multiplication and division and Logic operations like AND, OR, NOT, XOR.

• Memory Unit :Which holds the data in in terms of Program and files. The data stored can be accessed and used whenever required by the CPU for necessary processing.

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Central Processing Unit

• 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 data in RAM, when it needs it for processing.

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

Hardware: The Nuts and Bolts of the Machine - Memory

• The smallest usable unit of memory is measured by 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

Hardware: The Nuts and Bolts of the Machine – 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.

Hardware: The Nuts and Bolts of the Machine – Input and Output Devices

• Storage devices hold data (Perminant) not currently being used by the CPU. Data is commonly stored on a magnetic or optical disk. Each type of disk 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.

Hardware: The Nuts and Bolts of the Machine - Storage Devices

Software: Bringing the Machine to Life

• What is Software?

• System Software

• Application 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.

Software: Bringing the Machine to Life –What is Software?

Software programs create useful output

• 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 .

Software: Bringing the Machine to Life –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 software

Database management Presentation programs

Graphics programs Networking software

Web design tools and browsers Internet applications

Communications programs Utilities

Entertainment and education Multimedia authoring

Software: Bringing the Machine to Life - Applications

Computer applications

• Computer Database : instead of millions of folders and papers, it stores data and make them easy to access and change it ,allow many users access same data throw database management system .

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Computer applications (cont.)• Computer graphics : graphics created by

representation and manipulation of image data by a computer .– Examples Used in :

• Graphical user interface

• Games

• Computer animation

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Computer applications (cont.)

• Image processing : extracting image information .– Examples Used in :

• Objects and human Recognition

• Detecting manufacture defects

• Enhancement of important images

• Get effects and analyze it

• Medicine - You can diagnose

diseases.

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Computer applications (cont.)

• Computer Networks : connecting computers with each other and exchange data – Example : World wide web

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Computer applications (cont.)

• Web sites and applications : is a set of related web pages and applications accessed over a network such as the Internet or intranet.

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Computer applications (cont.)

• Artificial intelligence : is the systems and applications that undergo the human intelligence , it can be learned and give results with very high accuracy – Such as :

• Neural networks – Use learning in prediction and recognition

• Genetic algorithms– Used in getting best solution to problem

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Computer applications (cont.)

• Mobile applications : application software is developed for low-power handheld devices– Examples :

• Control computer throw Bluetooth

• Mobile games

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Computer applications (cont.)• Special purpose Micro systems : systems

which designed to serve special purpose – Examples :

• ATM machine system• Banks microsystems

• Robotics :Robots are controlled by software.

– Example:• Control robot throw software from cam

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Computer applications (cont.)

• Wireless sensor networks : is a networks of agents which connected together to perform a task

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The Computer Generations1. First Generation Computers (1950's) : Vacuum Tubes

(valves), Low speed, Punched Cards Storage, Expensive .

2. Second Generation Computers (1960's) : start of using

Transistors, Faster, Smaller, Size, Less Expensive.3. Third Generation Computers (1970's) : Silicon Chips and

IC’s, Main Frame Computers, Magnetic Tape Storage.

4. Fourth Generation (1980's) : Very Large Scale Integration

(VLSI), PCs, Large Memory Sizes, Magnetic Disk Storage.

5. Fifth Generation (Late 1990's) : Laptop, Optical Storage,

Communication, Higher Speed, High Capacity, inexpensive.31

Classification of Computers

(a)According to the purpose of the computer.

(b) According to the operation size of computer.

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(a) Classification as purpose

1. General Purpose Computers: designed for general use (PCs, Laptops, . .)

2. Special Purpose Computer : designed to perform specific processing tasks.

Examples are those found in video games, cameras, digital watches, washing machines, robots etc.

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The Shapes of Computers Today

• Supercomputers

• Mainframe Computers

• Minicomputers

• Microcomputers, or Personal Computers

b) According to size and capabilities

According to size and capabilities(cont.)

Super computers • These computers are

characterized as being the fastest, with very high processing speed, very large size, most powerful.

• There are widely used in complex scientific applications like processing geological data, weather data, genetic engineering etc.

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The Shapes of Computers Today - Mainframe Computers

• Mainframe computers can support hundreds or thousands of users, handling massive amounts of input, output, and storage.

• Mainframe computers are used in large organizations where many users need access to shared data and programs.

• Mainframes are also used as e-commerce servers, handling transactions over the Internet.

Mainframe System

The Shapes of Computers Today - Minicomputers

• Minicomputers are smaller than mainframes but larger than microcomputers.

• Minicomputers usually have multiple terminals.

• Minicomputers may be used as • Network servers • Internet servers.

The Shapes of Computers Today – Microcomputers, or Personal Computers

• Microcomputers are more commonly known as personacomputers. The term "PC" is applied to IBM-PCs or compatible computers desktop computers .

• Notebook (laptop) computers are used by people who need the power of a desktop system, but also portability.

• Handheld PCs such as PDAs (Personal Digital Assistant) lack the power of a desktop or notebook PC, but offer features for users who need limited functions and small size.

lesson 1 review: Essential concepts

• Name the four parts of a computer system.

• State the main components of the computer hardware.

• Differentiate between computer memory and external storage.

• Differentiate between the two main categories of computer software.

• Compare the five most common types of computer systems according to size and capability.

• Differentiate between the two main categories of computer systems according to purpose of use, giving examples.