Introduction to Computing Lecture-1-Computer (h/w & s/w) Muhammad Hafeez Department of Computer Science GC University Lahore

Today’s Agenda Computer Computer System Basic Computer Organization Types of Computers Data and Information

Computer An electronic device, operating under the control of instruction, stored in its own memory, that can access data (input), process the data according to specified rules, produce information and store in the information for future use. Software A set of instructions for a common purpose is called program or software

Characteristics of Computer Automatic: Once instructed, operate without human intervention Speed: Can perform 1012 basic arithmetic/ logical operations per second. Accuracy: If instructed accurately it never produce inaccurate results, however, if errors occurs they are result of thinking of programmer or incorrect input often called Garbage-In-Garbage-Out (GIGO) Diligence: No matter how much boring the task is for humans, if computer programmed accurately, it never gets bore or lose concentration during the execution of a task.

Characteristics of Computer Versatility: A general purpose computer perform versatile task. Memory: Computer can remember data and information for years and make them readily available whenever required. No. IQ: Most important if ever your program go wrong, it is NEVER the fault of computer as it has no IQ. It cannot do anything at its own. No Feelings: It has no feelings. It can only remember without like or dislike. Although the work in AI is progressing to make intelligent machines but goal is still far.

Von Neumann Architecture In 1945, a mathematician John Von Neumann proposed the idea of Flexible Computer – Stored Program Computer In the meantime another mathematician proposed similar type of idea – Turing Machine Both of these computers were programmable by storing data/ instruction in the computer memory

Von Neumann Architecture/ Computer System

System It has more than one elements All its elements are related logically All elements are controlled in a manner to achieve system goals

Computer System Computer System is a system that comprises of INPUTTING, PROCESSING & CONTROLLING, OUTPUTTING and STORAGE to convert DATA into INFORMATION.

Input Unit Accepts (read) instructions and data from outside world. Convert instructions and data into computer understandable form. This work is done by input interface. Supplies the converted instructions and data to storage unit (Primary Storage) for further processing.

Output Unit Accepts the produced results in coded form Convert coded results into human readable form. This task is done by output interface. Supplies converted results to outside world.

Storage Unit Storage unit holds: Data and information required for processing (input) Intermediate results of processing Final results of processing before they are released to outside world.

Two Types of Storage Primary Storage: Also called main memory Store input and intermediate results Processing unit access information at fast speed due to circuitry of memory chips. Volatile in nature as it loses the contents when power is turned off Available in limited size due to expensiveness Made up of semiconductor material

Two Types of Storage Secondary Storage: Also called auxiliary storage Provide more storage as it is cheaper than Primary memory that is limited in size Retain information even when the computer is turned off A computer system stores data and information in secondary storage which it is not currently working on. Magnetic disks are most common type of secondary storage.

Processing/ Controlling Unit Brain and Work Horses of Computer System resides in this Unit Two major parts are: Control Unit (CU) Arithmetic and Logic Unit (ALU) Both CU and ALU combined are known as Central Processing Unit (CPU)

Arithmetic and Logic Unit (ALU) A very basic ALU unit can perform All four Arithmetic Operations (+,-,/,x) Logical Operations (AND, OR, NOT) Comparison Operations (Less than, Greater than, Equal to, Not Equals to) The complexity and variations of these operations depends upon engineering design of ALU and purpose of Computer System in which ALU will be used ALU get data from Primary Memory process it (perform operations as required in the instructions) either store intermediate results back in primary memory or final results to output or secondary storage depending on job.

Control Unit (CU) Since ALU performs operations on data but what operations to perform and in what sequence? As part of CPU, Control Unit (CU) receive instructions from main memory that were originally entered by programmer. Main tasks are: Interpret instructions Direct the concerned element (ALU, Memory, Input, Output) to perform task necessary for completion of job. The operations CU perform to complete a task is called Machine Instruction Cycle.

Control Unit (CU) Since ALU performs operations on data but what operations to perform and in what sequence? As part of CPU, Control Unit (CU) receive instructions from main memory that were originally entered by programmer. Main tasks are: Interpret instructions Direct the concerned element (ALU, Memory, Input, Output) to perform task necessary for completion of job. The operations CU perform to complete a task is called Machine Instruction Cycle.

Types of Computers One the basis of size, speed and Input/ Output variations, computers have following types: Laptops Tablets Desktop (Personal Computer) Servers Mainframe Super Computer Mobile and Gaming Devices

Types of Computers Laptops Tablets Desktop (Personal Computer) Servers Thin, lightweight, mobile computer with screen in its lid and keyboard , processor in its base. Laptop operate on batteries Tablets Smaller than laptop and larger than phone, operate on touch screen Desktop (Personal Computer) Placed in stationary location also called personal computer. CPU and Input/ Output devices are separately attached Servers Mobile and Gaming Devices

Types of Computers Servers Mobile and Gaming Devices A dedicated computer designed to provide services to other computers on a network Services include storing their contents, and managing hardware/ software for them Servers can serve from two to several hundreds devices and computer connected to them depending on size of server Mobile and Gaming Devices Smart phones Digital cameras Portable and digital media players

Modern Computers

Inside the Modern Computer

Inside the Modern Computer

Data and Information Computers input data and produce information. Data: A collection of unprocessed items that include text, numbers, images, audio and videos Information: Information conveys meaning of data to the user. Information are used for decision making.

Data and Information

Concepts Covered

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