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PC Components, Features, System Design
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Hardware Outside the Case Inside the Case
Input/Output devices: connected through Ports Peripherals: monitor, keyboard, mouse, printer Inside the Case Systemboard or Motherboard Memory, such as SIMMs and DIMMs Interface Cards for monitors, scanners ... Power Supply Hard, floppy, and CD-ROM Drives
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Software Operating Systems, which consist of:
Program files controlling Input/Output A means of Booting the system Interfaces Command-driven, such as DOS Menu-driven, such as the DOS Shell Icon-driven, such Windows and Macintosh May be Multitasking Examples of Operating environments are DOS, Windows, OS/2, Mac OS, UNIX
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Applications Software
Types: Word processors such as Word and WordPerfect Spreadsheets such as Excel and Lotus 123 Database management such as Access Graphics Communications Games Installed from Disk or CD-ROM
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Directories Root or main directory, created when a hard drive is first formatted Subdirectories or folders for program applications and data files Paths point to the location of a file folder and a particular file
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Hardware - Outside the Case
Input/output devices or peripherals Monitor Primary output device Displays images with pixels Keyboard Primary input device Mouse Pointing device Printer Produces paper output called hard copy
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Hardware - Outside the Case
Cables connected to ports
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Hardware - Inside the Case
Inside the computer case
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Hardware - Systemboard
The most important circuit board, it holds microchips and interface cards: CPU or microprocessor Does most of the computer’s “thinking” Coprocessor Speeds up performance of older CPUs ROM Read-Only Memory, unchanging Holds programs or instructions that tell the CPU how to perform many tasks
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Hardware - Systemboard
RAM Random-Access Memory, volatile Individual chips or banks of chips such as SIMMs, DIMMs or RIMMS System clock Times the activities of the chips on the systemboard CMOS configuration chip System chip that contains setup information such as time and date, and drive size and type
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Hardware - Systemboard
Bus Paths along which data is passed Expansion Slots Interface cards are plugged into these slots to enhance the computer’s hardware, such as: 16-bit ISA slots 32-bit VLB slots 32-bit and 64-bit PCI slots
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Hardware - Systemboard
Components on a systemboard
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Divisions of Memory Under DOS
Hardware - Memory Conventional memory - used by older XT computers Upper memory - used to load drivers Extended memory - used by Windows Divisions of Memory Under DOS
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Hardware - Circuit board
Plugs into expansion slots Some types of circuit boards: Video card Hard drive controller card Multi-input/output controller card Internal modems Scanner card Network Interface Card (NIC)
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Hardware - Circuit board
Circuit boards mounted in expansion slots
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Hardware - Expansion Card
Expansion card and port
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Hardware - Power Supply
Converts electricity, reducing it to a voltage the computer can use - either 5, 12, or 3.3 volts DC Runs a cooling fan when the computer is on Provides connectors to power the main Systemboard and Floppy, CD, Tape, and Hard drives
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Hardware - Power Supply
Power supply with connections
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Hardware - Secondary Storage
Hard drive Sealed case containing rotating disks and read/write heads Floppy disk drives 5 1/4” disks 3 1/2” double-density or high density disks CD-ROM drives, DVD drives Tape drives Removable drives
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A floppy drive subsystem
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Software Programs that instruct the computer to perform specific tasks
Operating system software DOS, Windows, OS/2, Mac OS, UNIX Applications software Word processor, spreadsheet, database, graphics, communications, games
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Software - Operating Systems
The operating system is stored in files on the hard drive but is executed from memory
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Software - Operating Systems
DOS First Operating System used by IBM PCs The most common OS of the 1980’s and early 1990’s Command-driven from DOS prompt Example: C:\> DIR A:
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Software - Operating Systems
C:\>time Current time is 6:12:09.41a Enter new time: C:\>ver MS-DOS Version 6.22 C:\>copy config.sys config.bak Overwrite CONFIG.BAK (Yes/No/All)?y 1 file(s) copied C:\> C prompt An operating system command-driven interface: the C prompt
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Software - Operating Systems
Windows 3.1 Menu-driven File Manager Choose from a list of options on screen to perform various operations Icon-driven Program Manager Graphical-User Interface Choose operations by selecting or clicking on pictures on screen
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A menu-driven interface: File Manager in Windows 3.1
Software - Interfaces A menu-driven interface: File Manager in Windows 3.1
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An icon-driven interface: Program Manager in Windows 3.1
Software - Interfaces An icon-driven interface: Program Manager in Windows 3.1
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An icon-driven interface: Windows Explorer in Windows 95
Software - Interfaces An icon-driven interface: Windows Explorer in Windows 95
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Software - Multitasking
Ability of the computer to perform more than one function at a time Example: Use a Modem, a Word Processor, and a Spreadsheet at the same time Requires newer CPUs, such as a 486 or Pentium Requires a special OS, such as Windows 95 or Windows NT
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Software - Multitasking
A multitasking environment allows two or more applications to run simultaneously
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Software - Operating Environment
Operating environment refers to the overall support that software provides to applications software DOS manages its single-tasking environment and relates to hardware in single-task fashion Windows 3.x performs some functions of an OS and provides an environment in which applications software works
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Software - Operating Systems
Advantages and Disadvantages of DOS
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Applications Software
Applications software falls into six main categories: Word processing Spreadsheet Database management Graphics Communications Games
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Applications Software
Designed to work on top of a particular OS An application written for one OS may not work with another Comes on floppy disks or CD-ROMs Usually installed on the hard drive
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How Software Works In the final stages of startup, the computer passes control to the OS When OS completes its startup procedures, control passes to the user For DOS users, the C prompt will appear Example: C:\> Files with extensions of .COM, .EXE, and .BAT can be run from the DOS prompt
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Software - The Boot Process
C:\>C:\WINDOWS\SMARTDRIVE.EXE MICROSOFT SMARTDrive Disk Cache version 4.0 Copyright 1991, 1992 Microsoft Corp. Cache size: 761,856 bytes Cache size while running Windows: 0 bytes Disk Caching Status Drive read cache write cache buffering A: yes no no B: yes no no C: yes yes no For help, type "Smartdrv /?" C:\> DOS prompt after booting
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How DOS Searches for Executable Programs
Path - tells DOS where to look for files If no path is given, DOS looks in the current directory If a path is given in front of the file name, DOS looks in the PATH provided Ex: C:\DOS\CHKDSK If the file is not found in the current directory, DOS looks in the path given by the last PATH command Ex: Path= C:\;C:\DOS\;C:\WINDOWS
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Copying Programs into Memory
DOS cannot execute a program directly from the hard drive or floppy disks DOS copies the program into RAM It goes to the first address occupied by the program to receive its first instruction DOS manages requested read/write tasks to and from memory It performs other requested tasks and returns to the application when done
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Applications software is stored in files but executed from memory
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Software - Errors When an error occurs, either
The applications program detects the error and displays its own error message The operating environment software detects the error and displays an error message
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Software - Errors Disk error in Windows 95
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Windows error while using Paintbrush
Software - Errors Windows error while using Paintbrush
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Software Interactions with Hardware
The user interacts with the applications program The applications program interacts with the OS The OS interacts with the hardware, possibly through device drivers
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Software Interactions with Hardware
Layers of software when printing
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