SOFTWARE • The software provides the commands that tell the hardware what tasks to perform, what to read and write, how to send the end result (the output) to a monitor and/or printer. • Software is the programs and data that a computer uses. • Software is kept on some hardware device such as a hard disk or floppy disk, but it itself is intangible. • Software consists of both programs and data. Programs are lists of instructions for the processor. Data can be any information that a program needs: character data, numerical data, image data, audio data, and countless other types. KINDS OF SOFTWARE • Application software (usually called just "applications") are programs that people use to get their work done. It may include data entry; update query and report programs, productivity software for spreadsheets, word processing, databases and custom accounting programs for payroll, billing and inventory. It is designed to help people with specific task such as making a spreadsheet of creating a graphic image. Example of Application Software: Word Processor Microsoft Word Lotus Word Pro Word Perfect Spreadsheet Software Microsoft Excel Lotus 123 Quicken Presentation Software Microsoft PowerPoint Lotus Freelance Graphics Database Software Microsoft Access Lotus Approach Web Browser Internet Explorer Netscape Navigator PIM (Personal Information Manager) - software designed to organize names, addresses, and random notes for easy and efficient retrieval. It is just like an electronic equivalent of a conven- tional book-type personal organizer. PIM usually features an automatic dialing telephone list, a programmable calendar and an automatic reminder scheduler. It is ideal for people with hectic schedules who spend a lot of time working with their computers. Example: Lotus Organizer • Operating Systems are software which controls the computer and runs applications, it keep all the hardware and software running together smoothly. What the Operating System does is communicate information from the application software to a computer's program. Example of Operating Systems: CP/M (Control Program for Microcomputer) – an Early Operating System MS-DOS PC-DOS Microsoft Windows Mac OS OS 2 Linux UNIX OPERATING SYSTEM'S COMPONENTS The User Interface The operating system's user interface is what users see onscreen and interact with when giving a computer instructions and commands. A user communicates to the computer either by typing commands at a command prompt or by issuing commands through a graphical user interface (GUI). The Kernel The operating system's core is its kernel. The kernel's job is to regulate disk files, memory management, program objectives and tasks, and program execution and processes. The kernel is considered the operating system's core because it controls a computer's hardware, and is responsible for either directly activating computer hardware or for interfacing with software that drives the hardware. The File Management System The file management system is the operating system's organizer, arranging files in hierarchical tree-like structure the root directory. Files are data collections with single, logical names. Filename extensions declare a files type: .txt identifies text data .jpg, .bmp, and .gif extensions identify graphic files. • Programming Languages are used to create all other software whether it is Operating system or Application software. Machine-Language –first generation languages Assembly-Language second-generation languages An assembly language, however, can be used only with one type of CPU chip or microprocessor. High-Level Languages - third generation, languages High-level languages often use words that are more like the English Language (List, Print, and Open) as commands that might stand for a sequence of tens or hundreds of machine-language instructions. The commands are entered from the keyboard, from a program in memory, or from a storage device, and are translated by a program that interprets them into machine- language instructions, Example of High Level-Languages FORTRAN (Formula Translation) – was the first comprehensive high level programming language ALGOL (ALGOrithmic Language) COBOL (Common Business Oriented Language) – a commercial and business programming language, concentrated on data organization and file handling and was widely used at one time in business. BASIC (Beginner’s All-purpose Symbolic Instruction Code Pascal (named for Blaise Pascal) LOGO was developed to introduced children to computer C Languages (C and C++) LISP PROLOG (PROgramming for LOGic) – used in research on Artificial Intelligence (AI) ADA – descendant of Pascal, was designed for military applications such as Strategic Defense Initiatives (Star Wars) missile program Forth and Fifth Generation languages – are even closer to natural languages or rely on graphical user interfaces (GUI) featuring symbolic icons and drag-and-drop technique and English-like statements. Example of Forth and Fifth Generation languages Delphi Visual Basic Visual C++ Visual Fox Pro INTEGRATED SOFTWARE PACKAGES - is a single software program that includes multiple applications. It generally includes a word processing program, an electronic spreadsheet program, database software, a personal management grogram and limited graphics capabilities. The applications have a common interface -they "look alike"- and users can cut and-paste data from one application to another. One of its advantages is their economy; they are cheaper compared to the combined cost of separate standalone software. It also requires less storage space on the computer hard drive. Examples of Integrated Software Packages 1. Microsoft Works 2. LotusWorks APPLICATION SUITES - is a bundle of application that were created, packaged and designed to work together. Like the integrated package, it includes a word processing program, an electronic spreadsheet program, database software, a personal management grogram and graphics applications. It is both powerful and versatile and offer more options for users to manipulate and organize data. A drawback however, is they require more computer memory than integrated packages. Examples of Application Suites 1. Microsoft Office 2. Lotus Smart Suite WHAT IS A COMPUTER VIRUS? A (computer) virus is a program (a block of executable code) which attaches itself to, overwrites or otherwise replaces another program in order to reproduce itself without the knowledge of the PC user. WHY DO PEOPLE CREATE COMPUTER VIRUS? People create viruses for several reasons. • Some people think it's funny to create mischief, by creating viruses. • Some people are angry (at dictatorships, at the military, at big impersonal corporations, at clients who don't pay bills, at lovers who rejected them, and at homosexuals). • Some people are intellectuals who want the challenge of trying to create a program that replicates itself. Too often, the program replicates itself too well and too fast and accidentally does more harm that the programmer intended. • Some people want to become famous (or infamous or influential) by inventing viruses. • People who create viruses tend to be immature. Virus can be transmitted by: • Booting a PC from infected medium • Executing an infected program • Opening an infected file Common routed for virus infiltration include • Floppy disks or other media that user can exchange • Email attachments • Pirated software • Shareware What are some virus symptoms? • Slower Operation • Decreased memory • A disk drive LED lighting up for no apparent reason 7 KINDS OF VIRUSES 1. File virus A file virus (also called a parasitic virus) secretly attaches itself to an innocent program so the innocent program becomes infected. Whenever you run the infected innocent program, you're running the virus too! Examples: Yankee Doodle (From Bulgaria in September 1989) Die Hard 2 (From South Africa in July 1994) Chernobyl (From Taiwan in June 1998) 2. BOOT-SECTOR VIRUSES On a floppy disk or hard disk, the first sector is called the disk's boot sector or, master boot record (MBR). A virus that-hide in the boot sector is called a boot-sector virus. Whenever the computer tries to boot from a drive containing an infected disk, the virus copies itself into RAM memory chips. Before hiding in the boot sector, the typical boot-sector virus makes room for itself by moving data from the boot sector to a "second place" on the disk. Unfortunately, what- ever data had been in the "second place" gets overwritten and cannot be recovered. The typical boot-sector virus makes the computer eventually hang (stop reacting to your keystrokes and mouse strokes). Examples: Stoned (From New Zealand in December 1987) Michelangelo (From Sweden in April 1991) Monkey (From the USA in October 1992) 3. MULTIPARTITE VIRUSES A multipartite virus hides .in two places: the boot sector and also the file system. If you remove the virus from just the boot sector (or from just files), you still haven't completely removed the virus, which can regenerate itself from the place you missed. If a virus is very smart, it's called a stealth polymorphic armored multipartite virus (SPAM virus): A stealth virus makes special efforts to hide itself from anti-virus software. For example, it tricks anti-virus software into inspecting a clean copy of a file instead of letting it read the actual (infected) file. A polymorphic virus changes its own appearance each time it infects a file, so no two copies of the virus look alike to anti-virus programs. An armored virus protects itself against anti-virus disassembly. Example: One Half (From Austria in October 1994) 4. Macro virus A macro virus hides in macros, which are little programs embedded in Microsoft Word documents and Excel spreadsheets. The virus spreads to another computer when you give somebody an infected document. During the past few years, e-mail has become prevalent, and so have macro viruses: they're more prevalent than all other viruses combined. Examples: Melissa (From the USA in March 1999) Class (From the USA in October 1998) Thus (From the USA in August 1999) 5. E-mail worm An e-mail worm is a malicious program that comes as an e-mail attachment and pretends to be innocent fun.