Course Code 114 Introduction to Computer Science Lecture 2 Basics of Computer Science Assoc. Prof. Hussam Elbehiery Egypt 2018

Basics of Computer Science A computer system is an integrated form of different components that work together to give a desirable result. It has different component and each works for a specific purpose; however, they generate a common result as required by the user.

Components of Computer System Hardware The physical components collectively form the hardware of a computer system. Hardware comprises of the equipment that helps in the working system of the computer. Software The hardware components can only function when software components are added to the computer system. Software is a program that performs different commands given by a user.

Hardware Monitor − It displays (visual) the result. CPU − It is the Central Processing Unit that controls the computer’s functions and transmits data. Motherboard − It is mainly accountable to establish communication between components and transmission of information. RAM − It is the Random Access Memory and responsible for the storage of programs that are currently running and also stores data temporarily. Hard Disk Drive − It is a permanent memory storage device. Floppy Disk Drive − It is hardly being used in recent times. Optical disks − It is a device that also store data. For example, CD, DVD, etc.

Relationship between Hardware and Software Hardware and software are mutually dependent on each other. Software acts as an interface between the user and the hardware. Both of them must work together to make a computer produce a useful output. Software cannot be utilized without supporting hardware. Hardware without set of programs is useless. Software development is very expensive and is a continuing expense. If hardware is the 'heart' of a computer system, then software is its 'soul'. Both are complimentary to each other.

Software Types of Software: A program is a sequence of instructions written to solve a particular problem. Software is a set of programs. Types of Software: Depending on the basic features and functionality, software can be categorized as: Operating Systems (OS) Application Software (AS) E-accessibility Software

Operating System This software helps to load the basic program automatically as soon as the computer is started. Operating Software Examples Microsoft Windows XP, Vista, Win 8, Win 10, etc. Mac OS X Panther, Cheetah, Snow leopard, etc. Linux Debian, Ubuntu, Fedora, Knoppix, Redhat, etc.

Application Software The software, which can be used on an installed operating system, is known as application software. Application Software Examples Office programs Microsoft Office, OpenOffice, LibreOffice, etc. Web browser Internet Explorer, Mozilla Firefox, Google Chrome, Opera, Safari, etc. Antivirus Program Norton, McAfee, Quick Heal, Avira, Kaspersky, etc.

E-accessibility Software The E-accessibility software components additional facilities to users such as: Voice recognition software Screen reader Magnifying tool On-screen keyboard Video games Learning software, etc.

Computer systems Computer is an electronic data processing device which: Accepts and stores data input, Processes the data input, and Generates the output in a required format.

The Von Neumann model John Von Neumann (1903 - 1957), is worthy of special mention. He developed a very basic model for computers which we are still using today. Von Neumann divided a computer’s hardware into 5 primary groups linked to CPU: Input/Output units Input Output Working storage Permanent storage

Input Unit This unit makes link between user and computer. The input devices translate the information into the form understandable by computer.

CPU (Central Processing Unit) CPU is considered as the brain of the computer. CPU performs all types of data processing operations. It stores data, intermediate results and instructions (program). It controls the operation of all parts of computer. CPU itself has following three components ALU(Arithmetic Logic Unit) Memory Unit Control Unit Output Unit This unit is a link between computer and users. Output devices translate the computer's output into the form understandable by users.

All types of computers follow the same basic logical structure and perform the following five basic operations.

Advantages High Speed Accuracy Storage Capability Versatility Reliability Automation Reduction in Paper Work Reduction in Cost

Disadvantages No I.Q (In-phase and Quadrature components) (Intelligence quotient) Dependency Environment No Feeling

Computer - Input Devices Following are few of the important input devices which are used in a computer: Keyboard, Mouse, Track Ball, Joy Stick Light pen, Scanner Graphic Tablet Microphone Magnetic Ink Card Reader(MICR) Optical Character Reader(OCR) Bar Code Reader Optical Mark Reader(OMR)

Computer - Output Devices Following are few of the important output devices which are used in a computer. Monitors Graphic Plotter Printer Speakers

Input & Output Device Input Device Output Device Mouse Monitor Microphone Speaker Keyboard Printer Camera Earphone Scanner Projector Trackball Touchpad Plotter Joystick

CPU (Central Processing Unit) Memory or Storage Unit This unit can store instructions, data and intermediate results. This unit supplies information to the other units of the computer when needed. It is also known as internal storage unit or main memory or primary storage or Random access memory (RAM). Its size affects speed, power and capability. Primary memory and secondary memory are two types of memories in the computer.

Memory unit is: The amount of data that can be stored in the storage unit. That in which storage capacity is expressed in terms of Bytes.

Sr.No. Unit Description 1 Bit (Binary Digit) A binary digit is logical 0 and 1 representing a passive or an active state of a component in an electric circuit. 2 Nibble A group of 4 bits is called nibble. 3 Byte A group of 8 bits is called byte. A byte is the smallest unit which can represent a data item or a character. 4 Word A computer word, like a byte, is a group of fixed number of bits processed as a unit which varies from computer to computer but is fixed for each computer. The length of a computer word is called word-size or word length and it may be as small as 8 bits or may be as long as 96 bits. A computer stores the information in the form of computer words.

Unit Description Kilobyte (KB) 1 KB = 1024 Bytes Megabyte (MB) 1 MB = 1024 KB GigaByte (GB) 1 GB = 1024 MB TeraByte (TB 1 TB = 1024 GB PetaByte (PB) 1 PB = 1024 TB

Control Unit This unit controls the operations of all parts of computer but does not carry out any actual data processing operations. Functions of this unit are: It is responsible for controlling the transfer of data and instructions among other units of a computer. It manages and coordinates all the units of the computer. It obtains the instructions from the memory, interprets them, and directs the operation of the computer. It communicates with Input/Output devices for transfer of data or results from storage. It does not process or store data.

ALU (Arithmetic Logic Unit) This unit consists of two subsections namely Arithmetic section Logic Section

Computer Generations The generation term was used to distinguish between varying hardware technologies. But nowadays, generation includes both hardware and software. There are totally five computer generations known till date. Each generation differed in their time period and characteristics. Following are the main five generations of computers.

Computer - Types

Assoc. Prof. Hussam Elbehiery Thank you With all my best wishes Assoc. Prof. Hussam Elbehiery