PC Components,

Features,

System Design

Hardware

Outside 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

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

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

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

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

Hardware - Outside the Case

Cables connected to ports

Hardware - Inside the Case

Inside the computer case

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

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

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

Hardware - Systemboard

Components on a systemboard

Hardware - Memory

Divisions of Memory Under DOS

Conventional memory - used by older XT computers

Upper memory - used to load drivers Extended memory - used by Windows

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)

Hardware - Circuit board

Circuit boards mounted in expansion slots

Hardware - Expansion Card

Expansion card and port

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

Hardware - Power Supply

Power supply with connections

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

A floppy drive subsystem

A floppy drive subsystem

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

Software - Operating Systems

The operating system is stored in files on the hard drive but is executed from memory

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:

Software - Operating Systems

An operating system command-driven interface: the C prompt

C:\>timeCurrent time is 6:12:09.41aEnter new time:

C:\>verMS-DOS Version 6.22

C:\>copy config.sys config.bakOverwrite CONFIG.BAK (Yes/No/All)?y

1 file(s) copiedC:\> C prompt

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

Software - Interfaces

A menu-driven interface: File Manager in Windows 3.1

Software - Interfaces

An icon-driven interface: Program Manager in Windows 3.1

Software - Interfaces

An icon-driven interface: Windows Explorer in Windows 95

Software - Multitasking

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

Software - Multitasking

A multitasking environment allows two or more applications to run simultaneously

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

Software - Operating Systems

Advantages and Disadvantages of DOS

Applications Software

Applications software falls into six main categories: Word processing Spreadsheet Database management Graphics Communications Games

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

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

Software - The Boot Process

DOS prompt after booting

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:\>

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

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

Software

Applications software is stored in files but executed from memory

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

Software - Errors

Disk error in Windows 95

Software - Errors

Windows error while using Paintbrush

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

Software Interactions with Hardware

Layers of software when printing