COS 101: Introduction to Computing Sciences - Six Weeks Summary PDF

CSC 101 : Introduction to Computing Sciences Department of Computer Science. Ugwunna C.O (Ph.D)  Course Outline Definition of computers and computing system, historical background of Computers. Characteristics and generations of Computers. Basic functional compon...

CSC 101 : Introduction to Computing Sciences Department of Computer Science. Ugwunna C.O (Ph.D)  Course Outline Definition of computers and computing system, historical background of Computers. Characteristics and generations of Computers. Basic functional components of computing system, Classification of Computers hardware and software Computer hardware: functional components, modern input/output units. Software: system software, Introduction to Computer Networks and Internet. Operating systems and utilities, application software: areas of application of computers. Data storage and internal representation of data. 2  Course Outline(Contd) Bits and character representation concept of data, data compression, records, and files. Basic models of files processing and their advantages Diverse and growing computer/digital applications. Information processing and its roles in society. The Internet, its applications and its impact on the world today. The different areas/programs of the computing discipline. The job specializations for computing professionals. The 3 CSC 101 : Introduction to Computer Science WEEK 1  Definition INTRODUCTION TO COMPUTER WHAT IS COMPUTER? A Computer is a device or set of devices that work under the control of a stored program, automatically accepts and processes data to provide information. A computer accepts and then processes input data according to the instructions it is given. The elements of any sort of processing are INPUT, PROCESSING, STORAGE, and OUTPUT 5  Definition Computing: The process of utilizing computer technology to complete a task. Computing may involve hardware and/or software, but must involve some form of a computer system. Most Individuals use some form of computing everyday e.g. sending e-mail, telemedicine, business transaction and many more. 6  Definition Computing includes: designing, developing and building hardware and software systems; designing a mathematical sequence of steps known as an algorithm; processing, structuring, and managing various kinds of information; 7  Definition The field of computing includes : Computer engineering, Software engineering, Information systems, Information technology and Computer science, Computer science : is the study of the theory, experimentation, and engineering that form the basis for the design and use of computers. 8  History of Computer Science and their generations. History of computer development is often mentioned in reference to different generations of computing devices. Each generation of computer is characterized by a major technological development that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, more powerful, more efficient and reliable devices. 9  History of Computer Science and their generations. First Generation (1940-1956) - Used vacuum tubes for circuitry and magnetic drums for memory - Very Big - Very expensive - Consumes electricity - Generate a lot of heat - They relied on machine language for performance - Solve one problem at a time - Input was based on punched cards and paper tape 10  History of Computer Science and their generations. Universal Automatic Computer (UNIVAC) - 1951 - First fully electronic digital computer built in the U.S. - Created at the University of Pennsylvania ENIAC(Electronic Numerical Integrator And Calculator ) First general –purpose computer weighed 30 tons contained 18,000 vacuum tubes 11  History of Computer Science and their generations. Second Generation – 1965-1963 1956 – Computers began to incorporate Transistors Replaced vacuum tubes with Transistors 12  History of Computer Science and their generations. Second Generation (1956-1963) - They used Transistors - Smaller, faster, cheaper and more energy efficient computers - Still relied on punched cards for input and output - Transition from binary machine language to symbolic or assembly language - High level programming languages were also developed, such as BASIC, COBOL and FORTRAN - The first set of computer that stored their instruction on memory 13  History of Computer Science and their generations. Third Generation – 1964-1971 Development of Integrated Circuit Integrated Circuits are transistors, resistors, and capacitors integrated together into a single “chip” Interaction through keyboards and mouse. Smaller and Cheaper Computers. Development of Operating System(OS) OS is the set of programs that controls a computer. 14  History of Computer Science and their generations. Third Generation – 1964-1971 Integrated Circuit 15  History of Computer Science and their generations. Fourth Generation – 1971-present Availability of microprocessor Thousands of integrated circuits were built onto a single silicon chip Intel 4004 chip and IBM computers introduced Smaller computers were linked together to form networks This development led to Internet Development of Graphical User Interface (GUI) 16  History of Computer Science and their generations. Very Large Scale Integrated Circuit (VLSIC) Transistors, resistors, and capacitors 4004 had 2,250 transistors Pentium IV has 42 MILLION transistors 17  History of Computer Science and their generations. The First Microprocessor (Intel 4004)– 1971 The 4004 had 2,250 transistors four-bit chunks (four 1’s or 0’s) 108Khz Called “Microchip” 18  History of Computer Science and their generations. Birth of Personal Computers(MITS Altair) - 1975 256 byte memory (not Kilobytes or Megabytes) 2 MHz Intel 8080 chips Just a box with flashing lights cost $395 kit, $495 assembled. 19 History of Computer Science and their generations. Evolution of Electronics Microchip (VLSIC) Integrated Circuit Transistor Vacuum Tube 20  History of Computer Science and their generations. Fifth Generation (Present and Beyond) Based on Artificial Intelligence With the use of voice recognition, processing and super conductors Parallel processing and super conductors which is helping to make artificial intelligence a reality. Quantum computation, molecular technology will radically change the face of computers in years to come. The goal is to develop devices that will respond to natural language and capable of learning. 21  History of Computer Science and their generations. Fifth Generation (Present and Beyond) Artificial Intelligence 22 CSC 101 : Introduction to Computer Science WEEK 2 Types, Classification and Characteristics of Computer System Computer can be classified into the following: -Representation of numbers -Size - Purpose 24 Types, Classification and Characteristics of Computer System A. Representation of numbers Digital computers – They store or represent information in binary (digital) form Analogue computers – They represent information using physical quantities Hybrid computers – They combine analogue and digital computers’ properties 25 Types, Classification and Characteristics of Computer System B. Classification by size Super computer Mainframe computer Mini computer Micro computer – personal computer (PC) 26 Classification of Computer by Size. Supercomputer 27 Classification of Computer by Size. Mainframe Computer 28 Classification of Computer by Size. Minicomputer 29 Classification of Computer by Size. Micro-computer 30 Classification of Computer by Size. Micro-computer 31 Classification of Computer by Size. Micro-computer 32 Types, Classification and Characteristics of Computer System C) Classification by Purpose Special purpose computers – designed for particular job or task to solve problems General purpose computer- designed to solve a wide variety of problems and can be used to carry out different jobs. 33 Types, Classification and Characteristics of Computer System Characteristics of Computers Speed Capacity Versatility- it can be used for many things Diligence Accuracy Automatic 34  Benefit of Computer System Computer can be used in the following areas of life:- Engineering,  Science, Health, Marketing, Security, Education, Management, Production, etc. 35  COMPUTER SYSTEMS HARDWARE SOFTWARE 36  Hardware Hardware is the physical part of the computer that can be seen, touched or handled. The hardware consists of the physical and internal components of the system. The Hardware has the following basic components: Input Unit The Central Processing Unit Storage Unit Output Unit 37  (1) INPUT UNIT An input device is the main source by which computer receive information. It is the Electro-mechanical system, which aids the transferring of data into the computer, that is, it is the medium through which data can be supplied to the computer 38  (1) INPUT UNIT Examples are: a) Keyboard b) Mouse c) Joystick d) Trackball e) Light Pen and Stylus f) Graphic Tablet or Digitizer g)Touch Screen h) Scanner i) Magnetic Tapes and Cassettes Readers j)Audio input units or Voice Data Entry (VDE) k) Computer Disk and DVDs Readers l) Floppy and Hard Disk drives 39 A KEYBOARD 40 INPUT DEVICES. 41  INPUT DEVICES. Body Scanners CT (computerized tomography' (CT) (or 'computerized axial tomography' (CAT) scan)scanners and MRI scanners allow doctors to investigate what is happening inside a patient's body without intrusive surgery. 42  INPUT DEVICES. Body Scanners 43 MAGNETIC RESONANCE IMAGING(MIR). 44 MAGNETIC RESONANCE IMAGING(MRI). 45  (2) CENTRAL PROCESSING UNIT (CPU) This is otherwise known as the heart of the computer where - all manipulations are done, - main operation is being carried out. - It stand between the input and output devices. - It receives incoming data and instructions, works upon the data and sends to destination unit - I t consists of the arithmetic and logic unit, the control unit and the memory unit. It performs most of the calculations within the computer 46  CPU (CONTD) - responsible for the smooth running of your operating system as well as your application programs, such as word processors, spreadsheets and databases. - A small amount of memory associated with the CPU is used to perform these operations. - It also accesses and uses the main memory (RAM - Random Access Memory) within your computer. - is the single most important item within your computer that governs the overall speed of your computer. - The CPU's speed is measured in GHZ, the higher the GHZ rating of your CPU the faster your computer will run - 47  The System (Mother) Board Contained within the System unit All vital computer part are plugged directly to the system board. Other items such as the hard disk are attached to the system board, either directly or via cables. These boards are getting smaller and smaller as the components become more integrated 48 49  MAIN MEMORY The main memory is also called Internal storage or primary storage/memory. The Internal memory of a computer is an integral element of the processing unit and may be referred to as the computer’s working memory. It is used for storing software in the form of operating system, application programs and utility routines, etc. Internal storage has to be complimented by external storage, that is, storage external to the processor, which is referred to as “BANKING STORAGE”. This is used for mass storage whereas storage is used for immediate access requirements. 50 CSC 101 : Introduction to Computer Science WEEK 3  The System (Mother) Board contained within the CPU all vital computer part are plugged directly to the system board. Other items such as the hard disk are attached to the system board, either directly or via cables. These boards are getting smaller and smaller as the components become more integrated 52 53  Main Memory The main memory is also called Internal storage or primary storage/memory. The Internal memory of a computer is an integral element of the processing unit and may be referred to as the computer’s working memory. It is used for storing software in the form of operating system, application programs and utility routines, etc. Internal storage has to be complimented by external storage, that is, storage external to the processor, which is referred to as “BANKING STORAGE”. This is used for mass storage whereas internal storage is used for immediate access requirements. 54  The Control Unit coordinates and supervises all activities within CPU. (i) Receives instructions from the input unit and decode the instruction. (ii)Fetches data from the main memory and generates signals that are required to act on and execute the instruction. (iii)Keeps constant touch with input equipment, coordinates and keeps tracks of the instructions that have been executed. (iv) It does not partake in the processing function or store data, rather directs the sequence of operations in and outside the CPU. 55 (iii)The Arithmetic and Logic Unit (ALU) This is the unit where arithmetic and logical operations are carried out. It perform arithmetic operation such as addition, subtraction, multiplication, division, logical operation (AND, OR, NOT) and relational operations (, =, =, ). 56  Random Access Memory (RAM) main 'working' memory used by the computer modern computer can effectively house as much RAM as you can afford to buy. modern computers are supplied with over 32GB of RAM. a Microsoft Windows based computer will operate faster if you install higher size RAM Data and programs stored in RAM are volatile (i.e. The information is lost when you switch off the computer). 57  (3)STORAGE UNIT This unit is also known as Secondary storage, Auxiliary storage, Backing storage or External storage. Data coming to the computer are received by the memory and passed to a permanent storage device. This memory is used to store data not currently being operated on but which will be transferred to the main storage when required. Secondary storage is non-volatile and retains data even when the computer is turned off. There are many kinds of secondary storage; the most common ones are magnetic tape, magnetic disk and compact disk. 58  Difference between ROM and RAM Primary (RAM) Secondary 1 Primary storage/memory is Secondary storage or memory also called Internal or main is also called External or storage auxiliary storage 2 It has high speed It has low speed low 3 It is very expensive It is not expensive 4 It holds data or programs It holds data or programs temporary permanently 5 It holds programs and data It holds program or data that in current use in CPU will still be used in primary storage 6 It is faster It is not fast (as primary) 59 (4) OUTPUT UNIT An output unit is a medium which a computer uses to produce out processed or computed results for users in readable form. Results are either soft copy or hard copy type. A software copy output is the result displayed on the monitor while hardcopy is the output printed on paper. Output devices on the other hand, decode the data into information. Examples are: Monitors Printers Plotters Computer Output Microfilm (COM) Voice Output 60  COMPUTER SOFTWARE Software can be defined as the sets of instruction and procedures passed to the computer to perform certain activities or tasks. That is, it is the set of instruction directed to a computer system to perform a specific task. It is often called computer program. It is the program, which direct the operations of computer systems. It is the invisible part of the computer system. Without the software, the computer system is useless. There are two types of software namely: System software Application software 61  SYSTEM SOFTWARE System software is sets of one or more programs designed to control and supervise the operation and performance of a computer system. They are the software that acts as interface between the hardware and the user or computer resources. The overall control of the hardware operations and the user self-written programs is done by the system software. The systems software may be divided into the following: Operating systems Utilities and service programs Translators Database Management System 62 Operating System (OS): is a software that manages the resources of the computer. The workings of all hardware components as well as execution of application programs are controlled by the operating systems (OS). Those programs are concerned with the internal control and co- ordination of all aspects of the computer system, Utilities and service programs: are used for general housekeeping on the computer. They are system programs that provides useful service to the user of the computer by providing facilities for performing common tasks in a routine nature. These tasks are: Formatting a disk, copying of files, sorting, printing, editing, back-up e.t.c 63  Utilities and service program Continued These services include translators for any languages supported by the system and utility programs such as program editors and other aids to programming; - graphical user interfaces (GUls) providing intuitive, easily learned methods for using microcomputer systems. 64  APPLICATION SOFTWARE Application software or program is a computer program designed to help users perform a certain kind of activity. Depending on the task(s) for which it was designed, an application program can manipulate text, numbers, graphics or a combination of these elements. Application software consists of a number of programs designed to perform specific tasks for users. 65  SUMMARY Computer is made up of two components: Hardware Component Software Component Hardware Component The Hardware has the following basic components:  Input Unit  The Central Processing Unit  Storage Unit  Output Unit 66 Software Component There are two types of software namely: System software Application software The systems software may be divided into the following: Operating systems Utilities and service programs Translators Database Management System 67  What is an Operating System? An operating system (OS) is the interface between the user and the hardware. It implements a virtual machine that is easier to program than bare hardware OS provides standard services (an interface) which are implemented on the hardware, including: Processes, CPU scheduling, memory Management- file system, networking OS coordinates multiple applications and users in a fair and efficient manner - The goal of OS development is to make the machine convenient to use and efficient 68 Why Study Operating Systems? Abstraction — how do you give the users the illusion of infinite resources (CPU time, memory, file space)? System design —tradeoffs between: performance and convenience of these abstractions -performance and simplicity of OS -- functionality in hardware or software Primary intersection point — OS is the point where hardware, software, programming languages, data structures and algorithms all come together 69 The main functions of operating systems the function of an operating system is to manage the resources of the computer system. Generally, the resources managed by OS are - CPU, - Memory, - Input/Output Devices, - Backing Store and Files. 70  Other functions include: interpretation of the command error handling- detecting and reporting malfunctioning peripherals; - Security: protection of data files and programs from unauthorized use; Accounting and logging of the use of the computer resources. - Program loading to the main memory for processing - Multiprogramming - Interrupt handling - Job Sequencing and Scheduling - File Management - Peripheral Control - Recovery from System Failure 71 Some operating systems are: OS/2, Windows 95, 98, ME, 7, 8, 9,10 Windows XP, VISTA, UNIX, MS-DOS, Windows NT etc. 72  - Single Program OS: allow one user’s program at a time Simple Batch Systems: Provides multiprogramming of batch programs but have few facilities for multi-access - Multi-access and Time-sharing: Allows multiple access to system resources and therefore share processors time to cope with numerous users - Real-time system: Used in any real time data processing technique 73  Graphical User Interfaces (GUl) The vast majority of microcomputer users are interested merely in using a computer as a tool, without any real interest in the technical details of its operation. A typical user will probably want to run one or more common general-purpose applications, organize files into directories, delete files and format disks. Though the operating system will provide these services, the user needs to have a certain amount of technical knowledge to perform these tasks. GUI helps to bridge the loopholes 74  Commercial Packages These are the kind of application packages that are produced by software professionals and be sold for a wide variety of users. This falls into two main categories: a) Special-purpose packages: Though commercial, it is designed for a specific purpose such as a section of an organization. Examples are - Airline Seat Reservation, - Theatre Seat Reservation - Hotel Room Reservation. - Point of Sales Software - A Payroll Program 75 b) General Purpose: These provide facilities which might be used in a wide variety of business situations and which might therefore be used across many department e.g. 1. Word-processing: These are programs that turn a computer system into a powerful typewriting tool. It helps us to produce letters, reports, magazines, memos, etc. Example of Word-processing programs are: Microsoft word. Page maker, WordStar, WordPerfect, PC Write, MultiMate, etc. 76 2. Database Management: They store and retrieve information such as customer lists, inventories and notes. These programs help us to record and maintain information about people, places, things and management reports of all types. Examples are MySQL, Dbase III & IV, FoxBASE, Oracle, FoxPro and Clipper, Microsoft Access, Paradox, 3. Spreadsheet: Spreadsheets are software packages that turn a computer system into a sophisticated electronic calculator. 77 GUIDELINE FOR ACQUISITION OF APPLICATION SOFTWARE The software to be acquired must be one that the use will improve the particular operating function of that business. High performance Ease in learning. If a software package is complex then training is required Be available when needed Good documentation: how the package is to be installed and use. 78  COMPUTER SYSTEM MAINTENANCE Computer care and maintenance is often overlooked by the average user. Yet, taking a few precautions as you work, and learning to use the computer and its file system properly, can save you trouble in the long run. perform a few simple clean up procedures and use a couple of maintenance utilities can make a big difference in how your computer performs. 79  You can reduce the number of freeze-ups, the number of fatal errors and the number of reboots your computer has. You can also reduce the amount of downtime your system experience as a result of having to cope with these problems, as well as reducing your stress level. Not only that, but with a little preventive maintenance and proper computer care, you can increase the overall speed and efficiency of your computer. 80  System Maintenance There are some basic clean up steps you should do regularly to keep your machine running well. They are: Deleting Temporary files, Running Scandisk, Emptying the Recycle Bin Running Defragmenter. 81  Temporary files- What are they? They are duplicates of a file you are creating or working on. Windows creates them and when you are done with the file and close it, the temporary file disappears. Most of the time when you reboot your computer Windows should delete these temporary files, sometimes it does not. Where are they found? In the C:\ Windows\Temp directory. (Not to be confused with the Temporary Internet Files directory). 82  Defragmenter Defragmenter is a utility built in to most versions of Windows. Its job is to organize your hard drive more efficiently. When files are saved to the hard drive they are not necessarily saved as a whole, they are broken up and saved in various spots on the hard drive. This is because the hard drive itself is divided into millions of chunks. 83  Scandisk Scandisk is a utility built into most versions of Windows. It looks for files that have been fragmented or corrupted in some ways. Usually if a computer is just shut off instead of being shutdown, or if the computer freezes or if there is a power outage, this will create the need to run scandisk and it may find fragmented or corrupted files. 84  Introduction to Computer Network Communication : When we communicate, we are sharing Information. This sharing can be local or remote Local Communication – Face to face Remote Communication- takes place over distance Telecommunication-means communication at a distance (tele is Greek for far) Data : refers to information presented in whatever form as agreed by the parties creating and using the data. Data is all kinds of facts, including, pictures, letters, numbers, and sounds. 85  DATA COMMUNICATION Data Communication is the exchange of data (in the form of O’s and 1’s) between two devices via some form of transmission medium (such as a wire cable). For data communication to occur, the communicating devices must be of a communication system made up of combination of hardware (Physical component) and software (programs). 87 Data Communications  Effectiveness of Data Communication Depends on four fundamental characteristics Delivery : The system must deliver data to the correct destination. Data must be received by the intended device or user and only by that device or user. Accuracy: The system must deliver data to the correct destination. Data that have been altered in transmission and left uncorrected are unusable. 89  Effectiveness of Data Communication Timeliness: The system must deliver data in a timely manner. (video and audio). This kind of delivery is called real-time transmission. Jitter : refers to the variation in the packet arrival time. Uneven delay in the delivery of audio and video packet. 90  Five components of data communication Message : information(data) to be communicated Sender : The sender is the device that sends the data message. It can be a computer, work station, etc. Receiver: device that receive the message. Transmission medium: the physical path by which a message travels from the sender to the receiver e.g. : twisted-pair wire, coaxial cable, fibre-optic cable and radio waves. Protocol: set of rules that govern data communications. It represents an agreement between the communicating devices. Without a protocol, two devices may be connected but not communicating. 91  DATA COMMUNICATION The public switched telephone network (PSTN) is used to carry both voice and data communication. The public switched telephone network started as an analog network designed to handle analog voice signals but it has gradually been converted from an analog to a digital network. 92  DATA FLOW Communication between two devices can be simplex, half duplex or full duplex Simplex : communication is unidirectional, only one of the two devices on a link can transmit; the other can only receive. Keyboards and traditional monitors are example, keyboard can only introduce input; monitor can only accept output. 93  DATA FLOW Half duplex: each station can both transmit and receive, but not at the same time. When one device is sending, the other can only receive and vice versa. 94  DATA FLOW Communication between two devices can be simplex, half duplex or full duplex Full duplex : both stations can transmit and receive simultaneously e.g. when two people are communicating by a telephone line, both can talk and listen at the same time. 95 Week 4: OPERATING SYSTEMS AND UTILITIES What is Operating System? An operating system (OS) is a computer program that manages all other user applications and programs in a computer. It is loaded into the computer by a boot program. It enables user applications to interact with a computer’s hardware. To run other programs, every computer has to have at least one operating system installed. OPERATING SYSTEM Microsoft Windows, Mac OS and Linux are examples of operating systems that enable the user to use programs or applications like MS Office, Notepad, and games on the computer. Android and iOS are examples of operating systems that enable the user to use programs or applications like games on mobile phones. It is necessary to have at least one operating system installed in the computer to run basic programs like browsers. Features of Operating Systems Here is a list of some important features of operating systems: 1.Provides a platform for running applications 2.Handles memory management and CPU scheduling 1.Provides file system abstraction 2.Provides networking support 3.Provides security features 4.Provides user interface 5.Provides utilities and system services 6.Supports application development 99 Functions of Operating System Processor Management: An operating system manages the processor’s work by allocating various jobs to it and ensuring that each process receives enough time from the processor to function properly. Memory Management: An operating system manages the allocation and deallocation of the memory to various processes and ensures that the other process does not consume the memory allocated to one process. Device Management: There are various input and output devices. An OS controls the working of these input-output devices. It receives the requests from these devices, performs a specific task, and communicates back to the requesting process. File Management: An operating system keeps track of information regarding the creation, deletion, transfer, copy, and storage of files in an organized way. It also maintains the integrity of the data stored in these files, including the file directory structure, by protecting against unauthorized access.  Security: The operating system provides various techniques which assure the integrity and confidentiality of user data. Following security measures are used to protect user data: Protection against unauthorized access through login. Protection against intrusion by keeping Firefall active. Protecting the system memory against malicious access. Displaying messages related to system vulnerabilities.  Error Detection: From time to time, the operating system checks the system for any external threat or malicious software activity. It also checks the hardware for any type of damage. This process displays several alerts to the user so that the appropriate action can be taken against any damage caused to the system. Job Scheduling: In a multitasking OS where multiple programs run simultaneously, the operating system determines which applications should run in which order and how time should be allocated to each application. 102 Advantages of Operating System There are several advantages of operating systems: Ensuring correct and efficient use of the computer’s hardware. Allowing different applications to run concurrently. Managing files and folders. Providing a user interface. Managing security. Managing resources. Managing printing. Providing a platform for software development. Disadvantages of Operating System There are several disadvantages of operating systems: They can be complex and difficult to use. They can be expensive to purchase and maintain. They can be vulnerable to attacks from malicious users. 104 Utilities Utilities or Utility programs are system softwares or programs that perform specific tasks. They help to maintain the proper and smooth functioning of a computer system and assist the Operating System to manage, organize, maintain, and optimize the functioning of the computer system. Utility Softwares perform certain tasks like virus detection, installation, and uninstallation, data backup, deletion of unwanted files, etc. Some examples are antivirus software, file management tools, compression tools, disk management tools, etc. Types of Utility Software 1. Antivirus A virus is a malicious software that enters the system along with a host program. It multiplies with time and makes several copies which in turn slows down and corrupts the system. An antivirus is a utility software that helps to keep the computer virus- free. It notifies when any malicious file is detected and removes such files. In addition, it scans any new device attached to the computer and discards any virus if there. It also scans the system from time to time for any threats and disposes of them. Examples of antivirus are McAfee Antivirus, Quickheal Antivirus, Windows Defender, etc. 106 2.File Management System These utility software are used to manage files of the computer system. Since files are an important part of the system as all the data is stored in the files. Therefore, this utility software help to browse, search, arrange, find information, and quickly preview the files of the system. Windows Explorer is a default file management tool present in the system. Some other examples of file management tools are Google Desktop, Double Commander, Directory Opus, etc. 3.Compression Tools An important part of a computer is storage space, it is very important to maintain this storage. Therefore, we use certain utility software to compress big files and decrease their size, these are compression tools. The format of the files changes while compressing and we cannot access or edit them directly. In addition, we can easily decompress the file and get the original file back. Examples of compression tools are WinZip, WinRAR, WinAce, PeaZip, 7-Zip, etc. 4. Disk Management Tools These utility software are used to manage data on disks. Moreover, they perform functions like partitioning devices, manage drives, etc. Examples of disk management tools are MiniTool Partition Wizard, Paragon Partition Manager, etc. 108 5.Disk Cleanup Tool This utility software helps to free up the disk space. In addition, the files which are no longer in use are removed from the disk. Examples are Razer Cortex, Piriform CCleaner, etc. 6.Disk Defragmenter This utility software helps to reduce the fragmentation and hence, reduces the access speed. Defragmenting refers to rearranging files and storing them in contiguous memory locations. Moreover, saves time in reading from files and writing files to disk. Examples of disk defragmenters are Perfect disk, Deflaggler, etc. 7.Backup Utility This utility software helps to back up the files, folders, databases, or complete disks. Moreover, backup refers to duplicating the disk information so that the data can be restored if any data loss happens. Advantages of Utility Software The advantages are as follows: 1.Enhances performance. 2.Manages space. 3.Manages files and data. 4.Helps to customize interface and desktop. 5.Helps to remove useless files. 6.Keep the system safe and secure. 7.Helps to recover files after a loss.  Week 5: BITS AND CHARACTER REPRESENTATION CONCEPT OF DATA Bits, bytes, nibble and word The terms bits, bytes, nibble and word are used widely in reference to computer memory and data size. Bits: can be defined as either a binary, which can be 0, or 1.It is the basic unit of data or information in digital computers. Byte: a group of bits (8 bits) used to represent a character. A byte is considered as the basic unit of measuring memory size in computer. A nibble: is half a byte, which is usually a grouping of 4 bytes. Word: two or more bits make a word. The term word length is used as the measure of the number of bits in each word. For example, a word can have a length of 16 bits, 32 bits, 64 bits etc. Bites and Bytes All of the data stored and transmitted by digital devices is encoded as bits. Terminology related to bits and bytes is extensively used to describe storage capacity and network access speed. The word bit, an abbreviation for binary digit, can be further abbreviated as a lowercase b. A group of eight bits is called a byte and is usually abbreviated as an uppercase B. Kilo, mega, giga, tera, and similar terms are used to quantify digital data. Bit - One binary digit Byte - 8 bits Kilobit - 1,024 or 210 bits Kilobyte - 1,024 or 210 bytes Megabit - 1,048,576 or 220 bits Megabyte - 1,048,576 or 220 bytes Gigabit - 230 bits Gigabyte - 230 bytes Terabyte - 240 bytes Petabyte - 250 bytes Exabyte - 260 bytes Use bits for data rates, such as Internet connection speeds, and movie download speeds. Use bytes for file sizes and storage capacities. 1024 KB: Kilobyte (KB or Kbyte) is often used when referring to the size of small computer files. 56 Kbps: Kilobit (Kb or Kbit) can be used for slow data rates, such as a 56 Kbps (kilobits per second) dial-up connection. 50 Mbps: Megabit (Mb or Mbit) is used for faster data rates, such as a 50 Mbps (megabits per second) Internet connection. 3.2 MB: Megabyte (MB or MByte) is typically used when referring to the size of files containing photos and videos. 100 Gbit: Gigabit (Gb or Gbit) is used for really fast network speeds. 16 GB: Gigabyte (GB or GByte) is commonly used to refer to storage capacity  Representing Numbers Numeric data consists of numbers that can be used in arithmetic operations. Digital devices represent numeric data using the binary number system, also called base 2. The binary number system only has two digits: 0 and 1. No numeral like 2 exists in the system, so the number “two” is represented in binary as 10 (pronounced “one zero”). Representing Text Character data is composed of letters, symbols, and numerals that are not used in calculations. Examples of character data include your name, address, and hair color. Character data is commonly referred to as “text.” Digital devices employ several types of codes to represent character data, including ASCII, Unicode, and their variants. ASCII (American Standard Code for Information Interchange, pronounced “ASKee”) requires seven bits for each character. The ASCII code for an uppercase A is 1000001. Extended ASCII is a superset of ASCII that uses eight bits for each character. For example, Extended ASCII represents the uppercase letter A as 01000001. Using eight bits instead of seven bits allows Extended ASCII to provide codes for 256 characters. Unicode (pronounced “YOU ni code”) uses sixteen bits and provides codes or 65,000 characters. This is a bonus for representing the alphabets of multiple languages. UTF-8 is a variable-length coding scheme that uses seven bits for common ASCII characters but uses sixteen-bit Unicode as necessary. ASCII codes are used for numerals, such as Social Security numbers and phone numbers. Plain, unformatted text is sometimes called ASCII text and is stored in a so-called text file with a name ending in.txt. On Apple devices these files are labeled “Plain Text.” In Windows, these files are labeled “Text Document”. ASCII text files contain no formatting. To create documents with styles and formats, formatting codes have to be embedded in the text. Microsoft Word produces formatted text and creates documents in DOCX format. Apple Pages produces documents in PAGES format. Adobe Acrobat produces documents in PDF format. HTML markup language used for Web pages produces documents in HTML format. Data Compression To reduce file size and transmission times, digital data can be compressed. Data compression refers to any technique that recodes the data in a file so that it contains fewer bits. Compression is commonly referred to as “zipping.” Compression techniques divided into two categories: lossless and lossy. Lossless compression provides a way to compress data and reconstitute it into its original state; uncompressed data stays exactly the same as the original data. Lossy compression throws away some of the original data during the compression process; uncompressed data is not exactly the same as the original. The software for compressing data is sometimes referred to as a compression utility or a zip tool. On laptops and desktop computers, the compression utility is accessed from the same screen used to manage files. Compressing files using File Explorer on a PC The process of reconstituting files is called extracting or unzipping. Compressed files may end with a.zip,.gz,.pkg, or.tar.gz. Records and Files A Record is a collection of related data contained in one or more files or a database. For example: records are the rows in a table. Several related fields can be used to compose a record. In a payroll system, for example, the record for an employee might consist of the following fields (possible types for these fields are shown in parentheses): Employee identification number (a whole number). Name (a string of characters). Address (a string of characters). Hourly pay rate (a number with a decimal point). Year-to-date earnings (a number with a decimal point). Amount of taxes withheld (a number with a decimal point). Thus, a record is a group of related fields. All the fields listed above belong to the same employee. A company might have many employees and a payroll record for each. A File is a group of related records. More generally, a file contains arbitrary data in arbitrary formats. In some operating systems, a file is viewed simply as a sequence of bytes—any organization of the bytes in a file, such as organizing the data into records, is a view created by the application programmer. It’s not unusual for an organization to have many files, some containing billions, or even trillions, of characters of information. 120  Type of files Master files : They are made up of sets of records containing information that can be updated by addition, deletion, or changing of data. It is also called dynamic file Update files: They consists of set of changes to master file fields or records in a master file may be changed added or deleted using an update file. These files are often retained for a period of time for security reasons. They are called change file. Reference files-Price lists, actuary tables etc with less alteration Historical Files- When a system has been redesigned so that a master file no longer required.  File Organization Random File Organization: If there is no need to read data from the disk in any particular sequence, and the data is to be used for file enquiry. Sequential file organization: When master files are to be stored and updated by transaction files, and when there is little need for the enquiry, it pays to organise data sequentially onto the disk in a way which mimics organization on magnetic tape Index-Sequential file organization: This involves writing data onto the disk as a sequential file but in Basic Models of Files Processing File Processing In earlier days, data was stored manually, using pen and paper but after computer was discovered, the same task could be done by using files. There are various formats in which data can be stored. e.g. Text files can be stored in.txt format while pictures can be stored in.png format etc. In case of computer files, data about data (metadata) can be stored in different lines, separated by spaces, commas or tab to resemble tables. Each file is placed in relevant folders for the ease of access. In Computer Science, File Processing System (FPS) is a way of storing, retrieving and manipulating data which is present in various files. Files are used to store various documents. All files are grouped based on their categories. The file names are very related to each other and arranged properly to easily access the files. In file processing system, if one needs to insert, delete, modify, store or update data, one must know the entire hierarchy of the files. Advantages of File Processing System Cost friendly – There is a very minimal to no set up and usage fee for File Processing System. (In most cases, free tools are inbuilt in computers.) Easy to use – File systems require very basic learning and understanding, hence, can be easily used. High scalability – One can very easily switch from smaller to larger files as per his needs. 124