Computer Fundamentals

1. Chapter-1 Computer Fundamentals By: Mr. Birbal Jat PGT-Computer Sc. KendriyaVidyalaya No 3 Jaipur

2. COMPUTER MEANS • C : Commonly • O : Operator • M : Machine • P: Particular • U: User • T : Trade • E : Education • R: Research

3. The First in Computer World • World’s first electronic digital computer- ENIAC. • India’s first built digital computer-SIDHARTH Made by ECI. • India’s first built super computer-PARAM Made by C-DAC. • First computer was established in main post office of Bangalore on 16 Aug 1986. • First computerized Post office – New Delhi. • PRADESH is computer language for Hindi Commands. • In 1971 census – IBM1401 computer was used in India. • Dr. Raj Reddy is the first Indian who get Ph.Ed. in computer Science. • SYSTMAIL is email service for Indian languages, provided by C-DAC. • MONTRA ONLINE- India’s first international internet service. • SIKKIM is the first state where telephone directly is available on internet. • “dEI;wVjlapkjlwpuk“%& ns’k dh igyhdEI;wVjKkuijvk/kkfjrekfld if=dk

4. COMPUTER- AN INTRODUCTION • Computeris an electronic machine which calculates data very fast and provides results accurately. It is considered that when we provide accurate inputs in the computer, it provides 100% accurate outputs. • COMPUTER SYSTEM: It is set of hardware and software devices which are connected to each other to solve a specific problem. DEVICES: Monitor, keyboard, Mouse, Printer etc. • COMPUTER HARDWARE is a set of physical and magnetic devices which are used to make computers. We can see and touch these peripherals. Example: The outside border of a computer system. • COMPUTER SOFTWARE is a set of programs which are written in computer languages i.e. machine, binary. These are used to work on computer system. These provide instructions to various parts of a computer system. Example: Windows 98. • COMPUTER FIRMWARE is a combinatin of S/w & H/w. Computer Chips that have data recorded on them. Example: iPod, Bluetooth, iBook • LIVEWAREi : is the term used for the people associated with and benefited from the computer system. Example: getting feedback from users.

5. Characteristics of Computers Advantages: • Speed: Computers are much faster as compared to human beings. A computer can perform a task in a minute that may take days if performed manually. • Accuracy : Computers can perform all the calculations and comparisons accurately. • High Storage: Computers can store a large amount of information in very small space. • Reliability: Computers are immune (unaffected) to tiredness and boredom (dullness) or fatigue (weakness). Thus they are more reliable than human beings. • Versatility : Computers can perform repetitive jobs efficiently. They can work with different types of data and information like graphic, audio, visual, characters etc. Disadvantage: • Lack of Decision Making Power: Computers cannot decide on their own. They do not have this power which is a great asset of human beings. • IQ Zero: Computers are dumb machines with zero IQ. They need to be told each and every step.

6. EVOLUTION OF COMPUTER Note: Charles Babbage is called father of computer because he was the first person who imagine about stored program concept.

7. EVOLUTION OF COMPUTER

8. Functional Components of Computer • Input Unit: • It reads the data from the outside world. • It converts these data in computer acceptable form. • It supplies the converted data to the computer system for further processing. • Computer uses input unit for data entry and instructions feeding purposes. Some of the input devices are keyboard, mouse, MICR, OCR, OMR, Scanner, joystick , light pen, bar code reader etc. • CPU (Central Processing Unit): • It consists of ALU (Arithmetic Logic Unit) , CU (Control Unit) and Memory Unit. • It is also called the heart of the computer. It directs the operation of the I/O devices. • Output Unit: • It accepts result produced by the computer. • It converts these data in human acceptable form. • It supplies the converted data to the outside world. • The result given by the computer is called output . It can be obtained on output devices like monitor, printer, plotter etc.

9. Computer Generations

10. Classification of Computers Note: • General computers are used for ordinary tasks like banking , pay-roll systems. • Special computers are used for specific task like space research, weather forecasting, traffic control etc. • Analog computers work on physical values and transmits signal constantly. • Example – Petrol Pump where analog computer displays quantity & price of Petrol. • Digital Computers work only on binary digits and transmit signals discretely (isolated). • Hybrid computer is combination of both analog & digital computers. These are very costly and mainly used in hospitals to measures the BP/Temp/ other symptoms of Patients.

11. Comparison of Computer based on Size PARAM was India’s first super computer built by C-DAC Pune in guidance of Dr. Vijay P. Bhatnagar & Team. PARAM 10000 is the latest version of PARAM which provides weather report of one day within 01 minute and is the largest super computer of Asia. PACE (Processor for Aerodynamic Computation and Evaluation)was another Indian super computer produced byANURAG (Advanced Numerical Research & Analysis Group)

12. Other Computer Types • In recent years, design changes have reduced the size of micro computers, making computer technology portable and affordable. • Laptop computers are roughly the size of a large notebook. • PC (Personal Computer) defines a computer designed for general use by a single person. • Desktop : PC that is not designed for portability. • Palmtop: also known as PDAs (Personal Digital Assistants) that use flash memory instead of a hard drive for storage. • Workstation: a desktop computer that has a more powerful processor and additional memory, such as 3D graphics or game development. • Server: A computer that has been optimized to provide services to other computers over a network. • Client: A computer that sends request for some information to the Server over a network. • Wearable: The latest trend in computing is wearable computers, which have applications like (e-mail, multimedia) etc. Ex.- cell phones,

13. Computer Software

14. Operating System • OS is a set of programs that operates all activities of computer system. An OS is prepared to increase the efficiency of computer system. It is a link between user and hardware. • Functions of Operating System: • Memory Management: decides where and How files will be stored in memory. • Processor Management: Provides various tasks to CPU. • I/O Management: Performs various I/O functions. • File Management: Transfers and arranging of files. • Communication:provides communication between user and Screen. • Internal time Control: operates internal system clock.

15. Memory Management • The different types of policies & techniques for memory management are: • Single Contiguous Allocation: it is the simplest allocation technique. But has the poor usage of Processor and main memory. • Partitioned Allocation: it allows more than one job in the main memory at one time. But increases the complexity of the OS. It is the simplest for supporting the multiprogramming. • Paged Memory Allocation: In this each job is divided into pieces of the same size, calledpages. The physical memory is divided into pieces of same size called blocks. Any page can be placed into any block. This scheme eliminates fragmentation and increases memory and processor utilization. But it slow down the processor and increases cost of system. • Demand Paged Allocation: When a page is needed in main memory, the page which are loaded on demand, are present on Hard Disk. This is known as Demand Paged Allocation. It is beneficial when we have large virtual memory and some times it makes processor overloaded.

16. Process Management • We know that program is a set of instructions written in a programming language. • Process is a state of a program in execution. Or process is running program with some specific tasks to do. • A program is a passive entity whereas a process is an active entity. • When OS creates and kills processes it is called Process Tree. • The life time of a process can be divided in to 5 states: • New: The process has been created. • Ready: The process is waiting to be allocated to a processor. • Running : Instructions are being executed. When a process gets a control from CPU , it starts executing. • Suspended : A suspended process lacks some resource other than the CPU. Such processes are normally not considered for execution until the related suspending conditions is fulfilled. • Terminate: When the Process finally stops. A process terminates when it finishes executing its last statement. • The OS groups all information that it needs about a particular process into a data structure called PCB (Process Control Block) • It contains Process No., Priority No., Process State and Program Counter.

17. Process Scheduling • Scheduling refers to a set of techniques supported by operating system that controls the order in which the work to be done is completed. • The main objective of scheduling is to increase CPU utilization and performance. • We have to use some performance criteria to maximize the system performance . These are: • Throughput: it is measure of amount of work completed in a given time interval. Higher throughput means better system performance. It can be calculated by using the formula  The no of jobs completed / Total time to complete the jobs • Time slice / Time Quantum : a small unit of time (in milliseconds) given to a process by CPU. • Turnaround Time: It is the delay between job submission and job completion. • Waiting Time: It may be expressed as turnaround time, less than the actual processing time.

18. Types of Scheduling • Non-Pre-emptive : In this Scheduling , Scheduled job always completes before another scheduling decision is made. Therefore, finishing order of the jobs is also same as their scheduling order. The following Techniques use Non-Pre-emptive Scheduling: • FCFS (First Come First Served) • SJF (Shortest Job First) or SJN (Shortest Job Next) • Deadline Scheduling • Pre-emptive Scheduling: In this a Scheduling decision can be made even while the job is executing . It is more useful in high priority, which requires immediate response. The following Techniques use Pre-emptive Scheduling: • Round Robin Scheduling • Response Ratio Scheduling

19. Scheduling Techniques • FCFS(First Come First Serve): This is the simplest scheduling technique which is managed by FIFO (First In First Out) queue. i.e. The Process which requests the CPU first, is allocated the CPU First. • The CPU executes the jobs in the ready queue one by one. • Batch Processing is one obvious example of FCFS Technique in which all jobs in the batch are executed one by one. But Turnaround time for the very first job in the batch is the best and for the very last job it is worst. • SJF/SJN : In this technique, whenever a new job is to be admitted, the shortest of the arrived jobs is selected and given the CPU time. Throughput remains the same as in FCFS scheduling but waiting time improves. SJN associates with each job the length of its next CPU burst. (CPU burst is the CPU time required by a job to execute its continuous executable part.) • DEADLINE : In deadline scheduling the job with earliest deadline is selected for scheduling. Deadline of a job is the time limit within which a job must be over. If a job overshoots its deadline, it is said to be Deadline over run. Deadline over run is calculated as K=C-D where K is Deadline overrun ; C is job completion time and D is Deadline for a job.

20. Scheduling Techniques… • ROUND ROBIN : Round Robin (RR) Scheduling is aimed at giving all programs equal opportunity to make progress. This is implemented by ensuring that no program gets a second opportunity to execute unless all other programs have had at least one opportunity. • A small unit of time, called a time quantum or time slice, is defined. The ready queue (queue of programs waiting for CPU time)is treated as a circular queue. The programs in the ready queue are processed for the defined time slice, one by one. • RESPONSE RATIO : Response Ratio is calculated as follows Response Ratio =Elapsed time / Execution time received The job with highest response ratio is preferred over others. When a short job arrives, its response ratio is high, it is scheduled for execution immediately. A longer job would achieve high enough ratio only after a subsequent wait.

21. TYPES OF OPERATING SYSTEMs • SINGLE USER: Single user operating system is a type of operating system which allows only one user at a time. • The most popular single user OS is MS DOS (Microsoft Disk Operating System). • MULTIPROCESSING: In this OS two or more independent Processors are linked together in a coordinated system and the instructions are executed simultaneously. • It is used for major control applications like Rail , Road and Airways. • MULTIPROGRAMMING: In this OS more than one user programs are executed at the same time. It increases the resource utilization of CPU. • It is used to support multiple interactive tasks simultaneously. Some Popular Operating Systems: MSDOS, UNIX,WINDOWS , LINUX. Mac, BOSS, Solaris…

22. TYPES OF OPERATING SYSTEMs • Time Sharing: This OS operates in an interactive mode with a quick response time. The user sends a request and the OS processes it and a response is displayed. • Real Time: In this OS the jobs have fixed deadlines and the jobs have to be completed within their deadlines. It is used in Airlines booking, Wholesale market and manufacturing to see the current status. • Distributed : In this OS , the user can access remote resources in same manner as they do local resources. Data and process migration from one site to another is under the control of this OS. • It is used for Resource Sharing, Load Sharing, Reliability and Communications. • Network OS: it is used to support networking and servers. It provides file sharing , print sharing, backup of data etc. • Example : Windows NT server, Windows 9x, OS/2 and Macintosh

23. Internal Parts of Computer • Microprocessor: is a computer processor on a microchip made of silicon metal. It is sometimes called a logic chip. Intel 4004 was the first Microprocessor. It has four major components like: • Control Unit : it controls all the functions like input , output , storage and process. • Arithmetic Logic Unit: it is capable to perform addition ,subtraction, multiplication, division as well as comparisons. • Register: it is a special temporary storage location within the CPU. To execute an instruction , the CU retrieves it from main memory and places it into a register. • BUS: it refers to an electrical pathway through which bits are transferred between the various computer components. Or we can say a bus is a collection of wires over which the computer sends information.

24. Internal Parts of Computer… • Clock Speed: it refers to the no. of pulses per second generated by an oscillator (Alternator). Usually it is measured in MHz (Megahertz pulses per second). • Processor: is the logic circuitry that responds to and processes the basic instructions that drive a computer. These have 8 to 64 bit word lengths. These are divided in two categories: RISC & CISC.

25. Internal Parts of Computer… • System Bus: it carries bits between CPU and only one peripheral at a time. There are three main buses: • Data Bus: it is an electrical path that carries 32 bits of data at once between CPU and Memory and vice versa. • Address Bus: it carries 32 bits memory address to read/ write from Memory to CPU. • Control Bus: it carries signals created by processor and other devices. • PCI ( Peripheral Component Interconnect) is a data bus standard developed by Intel Corporation. It is a 64 bit bus with 66 MHz speed. We can add various devices through it. • EISA ( Extended Industry Standard Architecture) is also a data bus standard developed by Compaq. It is a 32 bit bus and useful for multiprocessing and multitasking. It is expensive but has better data transfer rate.

26. Various Registers:

27. INPUT DEVICES

28. Output Devices

29. Memory • Introduction: After CPU, memory is the most important part. Memory is the place where data & instructions are stored. • Types of Memory: • Primary (Main) Memory • Secondary (Auxiliary) Memory • Cache Memory • Primary Memory is the internal part of computer. Data & instructions are stored on electronic circuits. It is also called semi-conductor memory. It can be of two types: • RAM (Random Access Memory) • ROM (Read Only Memory)

30. RAM v/s ROM

31. Types of RAM • Static RAM: (SRAM) • Data are stored permanently. • Expensive but fast. • Useful in multi-media. • No need of refreshing. • Used in cache memory & PC. • Dynamic RAM: (DRAM) • Data are transferred like electronic current. • Data are kept in micro-capacitors. • Refresh is essential otherwise data will be destroyed after sometime. • EDO RAM: (Extended Data Out) • Advance form of DRAM • Used in Pentium-I PCs • Faster than DRAM. • SD RAM: (Synchronous DRAM) • Faster than EDO RAM • Used in Pentium-II & III PCs • Increased access speed in MHz • RDRAM (Rambus DRAM): is the high speed memory but very expensive. • DDR RAM (Double Data Rate RAM): is the latest memory used in recent PCs.

32. Types of ROM • EEPROM: • ElectricallyErasable PROM • Information can be removed by electric signals. • It is the simplest way to store info in ROM. • Now it is used to store BIOS in Memory. • Example :Pen Drive • PROM: • Programmable ROM • User can store programs only once. • User can make micro code program can be made that are needed mostly. • The process of making program in PROM is called ‘Burning’. • Example: CD-R • EPROM: • Erasable PROM • Information can be removed by ultra violet rays. • Information can be re-write after removing previous information. • It is cheaper than PROM because it is re-useable. • Example: CD(RW) Cache Memory: is a semi-conductor (buffer)memory which lies between main memory and processor. It is mainly used for increasing the speed of RAM.

33. Secondary Storage Devices

34. Various Ports of Computers

35. Terms used in Computers • Buffer:it is a temporary storage area. A buffer will take information from one device and hold it until another device is ready to receive it. • Spooling: The collection of information from several sources at one point, followed by orderly delivery of that information to the device. E.g. a printer . • Access Time: is the time from the start of one storage device access to the time when the next access can be started. • Seek Time: is the time to position the head on a specific track on a fixed head disks. It is the time taken by electronic circuit to select the required head. • Latency Time: The time required by a sector t reach below the R/W head. On an average. • Heatsink: is a device that is attached to a microprocessor chip to keep it from overheating by absorbing its heat and dissipating (dissolve) it into the air. There are two types of heatsink. • Active heatsink that comes with a Fan. • (ii) Passive heatsink that comes without fan.