Software Tools Instructor: Sanchita Mal-Sarkar Course: IST 203 Computer • An electronic machine that accepts input, processes data, stores data, and produces output. • Data can be numbers, text, images, graphics, and sound, etc. • Computer program is a set of instructions. Without it computer is useless. • Programming languages allow us to write these instructions (e.g. C, C++, Java, etc). Types of Computers • Computers are classified by their size, speed, and cost. • Microcomputers - desktop or tower. - A notebook computer - Personal digital assistant (PDA) • Minicomputers • Mainframes • supercomputers Microcomputers • Microcomputers => Also called personal computers. • These computers are typically used by a single user, usually at home or at office. They can be of different shapes and sizes. • A notebook computer (laptop) => small and light. Portable (standard desktop does not have). It can run on power from an electrical outlet or batteries. Expensive. • Personal digital assistant (PDA) =>more portable than notebook computer. It has limited capability. Also known as palmtop. Minicomputers • Minicomputers => Somewhat larger than microcomputers. The computing capability of a minicomputer may be more than a microcomputer. • Usually a company purchases a minicomputer when it needs to share large amount of data among many users. • Each user inputs processing requests and views output through a terminal. • The terminal has a keyboard for input and a display screen for output, but it does not process the user’s data. The processing requests will be transmitted from the terminal to the minicomputer. Mainframes • Larger and powerful than minicomputers. • The mainframe computers can handle many more users than a minicomputer. • These are used to provide centralized storage, processing, and management for large amounts of data. • Insurance companies use mainframes to process information about millions of policyholders. Supercomputers • The largest and fastest computers. • First developed for high volume computing tasks, such as weather prediction. • These are also used in a large corporation because they can process tremendous volume of data in a relatively shorter time compared to other computers (microcomputers, minicomputers, and mainframes). Computer system • A computer system consists of a computer, peripheral devices, and software. • The computer itself can take care of the processing function, but it needs additional components, called peripherals, to accomplish its input, output and storage functions. • Example of an internal peripheral device is hard disk drive. Computer Hardware • Hardware is the physical component of a computer. • Hardware is the equipment used to perform the necessary computations. • Examples: Main memory (RAM, ROM), secondary memory (hard disk drive, floppy disk drive), CPU, input devices (keyboard and mouse), and output devices (monitor and printer). Hardware Components of a Computer System Central Processing Unit (CPU) • Arithmetic-Logic Unit • Control Unit Input Devices • • • • Secondary Storage • Magnetic disk • Optical disk • Magnetic tape Keyboard Computer mouse Touch screen Source data automation Output Devices • • • • Printers Video display terminals Plotters Audio output Communications Devices Primary Storage Central Processing Unit (CPU) • Coordinating all computer operations. • Performs arithmetic and logical operations on data. • To process a program stored in main memory, - CPU retrieves each instruction in sequence. - Interprets the instruction to determine what should be done. Retrieves any data needed to carry out that instruction Then CPU performs the actual manipulation. • CPU’s current instruction and data values are stored temporarily inside the CPU in special high-speed memory locations called registers. Central Processing Unit (CPU) • The CPU consists of a control unit and an arithmeticlogic unit. • Three kind of buses link the CPU, primary storage, and other devices in the computer systems. • The data bus moves data to and from primary storage. • The address bus transmits signals for locating a given address in primary storage. • The control bus transmits signals specifying whether to read or write data to or from a given primary storage address, input device, or output device. Data Bus, Address Bus, and Control Bus Central Processing Unit (CPU) Primary Storage 1 Arithmetic-Logic Unit 24 + 12 = 36 12 < 24 8 # T U Control Unit Data Bus Address Bus Control Bus Input Devices Output Devices Secondary Storage Main Memory • Computer memory is a set of storage locations on the main circuit board (motherboard). • Four types of memory: – RAM, Virtual memory, ROM, and CMOS (complementary metal oxide semiconductor memory) Random access memory • Consists of electronic circuits on the motherboard (main circuit board). • Temporarily hold programs and data while the computer is on. • Each circuit has address that is used by the microprocessor to transmit and store data. • RAM is constantly changing (volatile). • E.g. When we write a paper, the word processing program will be temporarily copied into RAM so that microprocessor can quickly access the required instructions. Virtual Memory • Today’s microcomputer software uses space on computer’s storage devices to simulate RAM if more needed. • This extra memory is called virtual memory. • How it works? • Suppose my computer is running a word processing program that takes up most of the memory in RAM, but I want to run a spreadsheet program at the same time. Virtual Memory (Cont.) • The OS moves the infrequently used segment of the word processing program into virtual memory on disk. • The spreadsheet program now can be loaded into RAM. • If that segment is later needed, it is copied from virtual memory back to RAM. • Disadvantage:It is much slower than RAM. Read-only memory(ROM) • Another set of electronic circuits on the motherboard inside the computer. • We cannot increase ROM capacity. • Manufacturer permanently installs ROM. • When computer is on, the sets of instructions in ROM checks • all the computer system’s components to make sure they are working and • activates the essential software that controls the processing function. Complementary metal oxide semiconductor(CMOS) • A chip installed on the motherboard. • Activated during the boot process. • Contains information about where the essential software is stored. • A small rechargeable battery powers CMOS. • It changes every time we add or remove hardware to the computer system. • CMOS is referred as semipermanent memory. Secondary Storage Devices • RAM retains data only when the power is on, so computer must have a more permanent storage option. • The most common magnetic storage devices are hard disk drive, floppy disk drives, and tape drives. Hard disk drive • Provides a storage area to be shared by all users of the computer. • Generally, the programs that are needed to operate the computer system are stored here. • Advantages over floppy disk: speed and capacity. Hard Disk Drive Internal Components Floppy disk drive • Most common magnetic storage device. • Users can have any number of floppy disks that can be inserted into computer’s floppy disk drive. • High density disk- capacity to store 1.44 MB. • Low-density disk - capacity to store 720 KB. Tape drive • Another magnetic storage device. • Provides inexpensive archival storage for large quantities of data. • Too slow to be used for day-to-day tasks. • Used to make backup copies of data stored on hard disks. • If a hard disk fails, data from the backup tape can be reloaded on a new hard disk. Compact Disk Read Only Memory (CD-ROM) • Optical storage device. • Uses laser technology to read and write data on compact discs (CDs). • High capacity and portability. Can store up to 680 MB, equivalent to more than 450 floppy disks. • Relatively slow access. Mainly used for software distribution and storing large data files such as graphics, animation, and video. Input Devices • Input device - keyboard, mouse. • Input devices translate data & programs that humans can understand into a form that computer can process. • When we press a letter or digit key on a key board, that character is sent to main memory and displayed on the monitor. • Keyboard consists of three major parts: main keyboard, keypads, and function keys. • A mouse is a hand-held device used to select an operation. Output Devices • Shows the result of processing data. • Output devices - monitor and printer. • Output devices translate the processed information from the computer into a form that humans can understand • Monitor is the TV-like device that displays the output from a computer. • Printer produces a hard copy of the text or graphics processed by the computer. Computer Software • Software consists of the computer programs that allow us to solve problems by providing sets of instructions. • Examples: DOS, Windows, Mac. Office family, Lotus, Netscape, Internet Explorer, Virus scans, tax programs, computer games, GUI Graphical User Interface. Computer Software • Computer hardware is useless without software. • Software is the set of instructions and associated data that direct the computer to do a task. • Software can be divided into two categories: • System software and application software. • System software helps the computer to carry out its basic operating tasks. • Application software helps the user carry out a variety of tasks. System Software • Manages the fundamental operations of the computer, such as – loading programs and data into memory, executing programs, saving data to disks, displaying information on the monitor, and transmitting data through a port to a peripheral device. • Four types of system software: operating systems, utilities, device drivers, and programming languages. Operating System • Collection of computer programs that control the interaction of the user and the computer hardware. • Responsible for directing all computer operations and managing all computer resources. • Controls basic input and output, allocates system resources, manages storage space, maintains security, and detects equipment failure. • A part of the operating system code is stored in a ROM and the rest of it resides on a disk. • Loading the operating system into memory is called booting the computer. Responsibilities of an Operating System • Communicate with user, receive and execute commands, show error messages. • Manage allocation of memory, processor time and other resources. • Collect input from keyboard, mouse, and provide data to running programs. • Convey program output to screen, printer, or other output device. • Access data from secondary storage. • Write data to secondary storage. • Maintains security (checks user-name , password, virus infection) Virus • Virus => unscrupulous programmers deliberately construct harmful programs (called viruses) that instruct your program to perform destructive activities, such as erasing a disk drive. • Virus protection software => Computer users can protect their computers by using virus protection software. • How it protects? Virus protection software searches executable files for the sequences of characters that may cause harm and disinfects the files by erasing or disabling those commands. Utilities • Another category of system software. • Augments the OS by taking over some of its responsibility for allocating hardware resources. • Many utilities come with OS. • Some independent software developers offer utilities for sale separately. • E.g. Norton Utilities by Symantec. Device driver • A computer program that can establish communication because it contains information about the characteristics of your computer and of the device. • Each peripheral device requires a device driver. • Helps the computer communicate with that particular device. • When we add a device to an existing computer, part of its installation includes adding its device driver to the configuration. Computer programming languages • Another type of system software. • Programmer uses to write computer instructions. • The instructions are converted into electrical signals that computer can manipulate and process. • E.g. Basic, Visual Basic, C, C++, Cobol, etc. Application software • Developed for a specific task , such as word processing( MS Word/ WordPerfect), accounting (Lotus 1-2-3/ Excel), or database management (Access/ dBASE). • We also use graphics and presentation software. • Most applications are purchased on diskette or CD-ROM. • They are installed by copying the programs from the diskettes/CD-ROM to the hard disk. Word processing software • Allows the user to store and modify text data electronically as computer files. • The software has formatting options to make changes in line spacing, margins, character size, and column width. • It can also check spelling, grammar, and punctuation. • Popular word processing packages: MS Word, WordPerfect. Spreadsheet Software • Spreadsheet software can be used to analyze and summarize numerical data. • Spreadsheet software creates a worksheet, composed of a grid of columns and rows. • You can write any character in each column. • You can write any number in each row. • The intersection of a column and row is called a cell. Each cell has a unique address (cell reference). • Using spreadsheet you can create graph (summary of data) • Spreadsheet software provides you with excellent printouts of the raw data or graphs created from the data. Database Management Software • Most popular types of application software. It is used to organize and manage data • A database is a collection of information stored in one or more computers. • A structured database is organized in a uniform format of records and fields. • A structured database contains data that describes a collection of similar entities. For examples, Name: Student# Student # of courses taken in Fall 2004 GPA Graphics & Presentation Software • Graphics and presentation software allow us to create illustrations, diagrams, graphs, and charts that you also can print and transmit to remote computers. • Most application software allows you to include graphics created by graphics software (Microsoft Paint or Adobe PhotoShop). • You can also use clip art (a collection of drawings) comes with software packages. • MS PowerPoint is a popular presentation software. You can create colorful presentations and transparencies. Data Communications • The transmission of text, numeric, voice, or video data from one machine to another is called data communications. • For example, Send an electronic mail to your friends around the globe. • The four essential components of data communications are a sender, a receiver, a channel, and a protocol. Sender => The computer that originates the message is called the sender. Receiver => The computer at the message’s destination is called the receiver. Data Communications Channel => The message needs some kind of medium to be transmitted. This medium is called channel. For example, telephone or coaxial cable, microwave signal, or optical fibers Protocol => The rules that establish an orderly transfer of data between the sender and the receiver are called protocols. • Computer software and hardware establish these protocols at the beginning of the transmission, and both computers have to follow the protocols to ensure accurate transfer of data. Networks • One of the most important types of data communications in the business world is a network connection. • A network connects one computer to another computers and peripheral devices to share data and resources. • There is a number of network configurations. • local area network (LAN) => computers and peripheral devices are located relatively close to each other, generally in the same building. • Client/server networks =>Some networks have file servers (one or more computers) that act as the central storage location for programs and that provide mass storage for most of the data used on the network. A network with a file server is called a client/server networks. Networks • Peer-to-peer networks => When a network does not have a file server, all the computers essentially are equal, and programs and data are distributed among them. This is called a peer-to-peer network. • Each computer that is part of the network must have a network interface card installed. This device creates a communication channel between the computer and the network. • Network software is also essential to establish the communications protocols. • Standalone computer => A microcomputer that is not connected to a network is called a standalone computer. Telecommunications • Allows us to send and receive data over telephone lines. • A modem connects a computer to a telephone jack. • At the sending site, modem converts the digital signal from a computer into analog (continuous wave) signals (sound waves) that can traverse ordinary phone lines (modulation). • At the receiving site, a second modem converts the analog signals back into digital signals (demodulation). Telecommunications Internet • The internet was originally developed for the government to connect the researchers around the world to share data. • Today, the internet is the largest network in the world that connects millions of people in almost 200 countries. • The use of internet: electronic mail => This is the capability to send a message from one user’s computer to another user’s computer where it is stored until the receiver opens it. Message passes through electronic links called gateways. World Wide Web (Web) => Web is a huge database of information that is stored on the network servers in places that allow public access. The information is stored as text files called web pages. Internet • Hyperlinks => a place on a computer screen that is programmed to connect to a particular file on the same network server, or on a network server on the other side of the globe. • Web browser => communication software that help us navigate the WWW is called web browsing software or web browser.