system software chapter 4 of computers: understanding technology (third edition) 1september 16, 2009...
TRANSCRIPT
System Software
Chapter 4 of Computers: Understanding Technology (Third
edition)
1September 16, 2009 - William Pegram
System Software in Context
• Hardware– Input (Ch. 2)– Processing (Ch. 2)– Output (Ch. 3)– Storage (Ch. 3)
• Software– System software(Ch. 4)– Application software (Ch. 5)
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System Software
• Operating Systems
• Utility Programs
• Language Translators – Compiler, Interpreter
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Operating Systems
• When computer is started, part of operating system is loaded into random access memory (RAM) from the boot drive (typically the hard drive)
• Functions of operating system– Managing main memory– Controlling peripheral devices– Managing file operations– Monitoring system performance– Providing user interface
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Operating System Functions
• Output buffers – selected areas of RAM which hold data waiting to be transferred to an output device – This frees the CPU to move on to something else; output device will often be slower – print spooling is example
• Multitasking – User can work on more than 1 application at the same time
• Drivers – programs that allow the operating system to communicate with a peripheral device – the driver is often specific to a specific device, manufacturer and model number; typically this means that the application program need only know how to communicate with Windows and not with each peripheral device
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Operating System Functions (cont.)
• Security features– Operating system can force user to enter a
correct username and password to access the computer
– Windows XP and Windows Vista can provide multiple user accounts on a single machine and different levels of privileges among the accounts
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User Interfaces
• Command line – e.g. DOS
• Graphical User Interface (GUI) – e.g. Windows
• Graphical user interface was used in the Alto computer developed by Xerox Palo Alto Research Center, and later used in the Apple Lisa and Macintosh computers
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Elements of GUI
• On-Screen desktop with graphical elements displayed – icons, buttons, etc.
• Display windows – title bar, scroll bar, and other common features
• Menus with drop down menus• Toolbars with icons• Dialog boxes to provide information and prompt
responses – tabs, radio buttons, checkboxes, text boxes, OK/cancel buttons
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Personal Computer Operating Systems
• Windows XP (ITN 114)
• Windows Vista
• Macintosh
• IBM OS/2
• Linux (ITN 170, ITN 270)
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Server Operating Systems
• Some operating systems are used with networks, allowing multiple users to connect to the server
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Server Operating Systems
• Novell NetWare• Windows NT Server• Windows 2000 Server (ITN 111)• Windows 2003 Server (ITN 115)• Windows 2008 Server • Unix (ITN 171 and ITN 271)• Linux (ITN 170 and ITN 270)
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Wireless Device Operating Systems
• Palm OS
• Windows Mobile
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Utility Programs
• Antivirus – Norton, Symantec, McAfee• Firewalls – security system that acts as
boundary to protect computer or network• Diagnostic• Uninstaller – remove all files associated with a
program• Disk scanner – identify bad sectors• Disk defragmenters • File compression – WinZip, PKZIP, and Stuffit
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Utility programs (cont.)
• Backup
• Disk toolkits – fix problems with a disk
• Spam blocker
• Anti-spyware – Windows Defender
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Language Translators
• Programmers generally write programs in high-level languages – Java, COBOL, Fortran
• Compilers translates entire program into machine language file; that file is then executed whenever program is run
• Interpreter translates one statement at a time without producing a file, so repeated runs require interpreter each time
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