How Software sw

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How Software (s/w) Hardware (h/w) Work together

• David Turton
• Conestoga College
• Institute of Technology and Advanced Learning
• http//www.conestogac.on.ca/dturton
• Doon 1D17 X3610

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Hardware Review

• Hardware has to interact with the CPU to function
• Data is transferred along busses on motherboard
• Programs and data must be loaded to memory to be
  processed
• BIOS contains startup (POST, CMOS config) and
  system (device interface) programs
• Common busses/expansion slots
• Memory bus
• ISA slots
• PCI bus
• AGP bus
• USB bus
• Firewire/IEEE 1394

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Objectives

• Explain how hardware talks to CPU
• IRQ's, I/O addresses, etc
• POST boot process
• Outline the (Windows) O/S's in use today
• Windows, UNIX, Linux, Mac
• Various flavours of Windows
• Identify what the O/S does for you
• Hardware/memory
• Files, applications, user interface
• Outline how the O/S interacts with hardware
• Drivers
• Real vs protected mode

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How Hardware CPU Talk
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System Resources

• IRQ - Interrupt Request
• a line/trace on the bus that a device uses to get
  the CPUs attention
• I/O Address
• number assigned to a device that s/w uses to get
  its attention
• Memory Address
• number assigned to physical memory on RAM or ROM
• eg video RAM
• DMA Channel
• numbered channel a device can use to address
  memory without disturbing the CPU

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Powering up a PCs consciousnessthe Boot Process

• BIOS tests essential h/w
• power-on self-test (POST)
• setup info configures h/w and s/w
• from CMOS, jumpers and DIP switches
• devices assigned system resources
• fixed-config first, then Plug-and-Play
• O/S loaded, configured and executed
• h/w devices matched w/ BIOS programs or drivers
• application s/w loaded (TSR or executed)

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Cold vs Warm and in-between

• Soft or Warm boot
• via
• CtrlAltDel
• software restart
• easier on PC
• sometimes is disabled
• May not clear virus in memory

• Hard or Cold boot
• turning power on
• power surge stress
• Reset button
• Earlier in boot process than Ctl-Alt-Del
• doesnt cause surge
• lose cached changes

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POSTCPU must execute the startup BIOS program

• Loads memory FFFF0H, always assigned to BIOS
• checks CMOS, battery, CPU
• if cold boot, checks first 16KB of RAM
• hardware is checked and assigned resources
• video controller errors conveyed by beeps, rest
  through monitor (doesnt check for actual
  monitor)
• begins search for OS

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Legacy devices hard-coded resource requirements
After resources assigned to legacy devices, PnP
devices get assigned from remaining resources
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Devices use IRQ's to get CPU's attention
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IRQ - Interrupt Request Number

• Voltage on IRQ line indicates h/w device wants
  CPU attention
• interrupt controller chip chooses lowest-numbered
  IRQ first
• note second controller links IRQ9 to IRQ2 for
  8-15
• so 8-15 take precedence over 3-7

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CPU uses I/O address to get device's attention-
also called port addresses or ports
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Example of what lines in a bus are used for
Expansion slot for the 8-bit ISA bus
Extension for the 16-bit ISA bus
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• Handling a Hardware Interrupt
• Device fires interrupt request
• Voltage on assigned IRQ line
• CPU gets interrupt number
• CPU uses interrupt table
• Address of code to handle interrupt
• (aka driver)
• Loads driver
• Processes data from device

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• Handling a Software Interrupt
• s/w sends interrupt code to CPU
• CPU looks at interrupt table
• Address of code to handle interrupt
• (aka driver)
• Loads driver
• Contacts device
• I/O address on address bus
• Data on data bus

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Boot processCMOS Information tells BIOS where
to look for the OS
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Varieties of Operating Systems (O/S)
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Common Operating Systems (Microsoft)

• DOS
• For early PC's
• Simple, had limitations
• Overlay GUI
• Windows 3.x
• Windows 9x
• 95, 98, 98SE, ME
• Graphical O/S, DOS core
• No longer supported

• Windows NT
• Total rewrite, away from DOS limitations
• More file access control
• Larger address space
• Basis for servers
• Windows 2000, XP, 2003
• Derived from NT
• Advanced file/memory management, less failures
• Improved central directory
• Massive storage/memory capabilities

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Common Operating Systems (non-Microsoft)

• Unix
• First network-centric O/S, from 1970
• Written in C, can be compiled to any platform
• Major servers on internet
• High capacity
• Very efficient
• Very reliable
• Linux
• Scaled-down Unix for PC's
• Open-source free downloads
• Reliable, efficient
• Good server capabilities

• OS/2
• IBM's entry into server market (1994)
• Similar to NT
• Died on market
• Mac OS
• First graphical O/S
• Graphical, design and games oriented
• Not business-oriented
• Didn't get economies of scale

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Major O/S Functions

• Manage hardware
• Interpreting software needs and hardware
  responses
• Plug-and-play auto-identification
• Manage BIOS device drivers
• Manage memory
• Virtual memory management
• Application isolation
• Manage files
• Creating, storing, retrieving, deleting,
  moving/copying
• Navigating directories, following links through
  FAT
• Hard drives, floppies, CD/DVD's, memory cards,
  etc.
• User interface
• Allows user to manage desktop, hardware,
  applications, data
• Provides graphical interface support
• Manage applications
• Install/uninstall
• Run applications, manage hardware interface

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User Interfaces

• Command-Driven
• Enter commands at a prompt
• DOS, UNIX, Linux
• Minimal overhead load
• Windows run command or cmd
• Note command is DOS cmd is Windows command
  prompt

• Menu-driven
• List of options displayed
• Drop-down menus show commands available
• In context of window contents

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User Interfaces cont'd

• Icon-driven
• GUI (graphical user interface)
• Select actions by clicking on icon (picture)
• Applications files become objects
• Drag-and-drop objects from one location to
  another

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Shell Kernel
applications
User interfaces

• Shell
• Interface for users
• Command, menu and icon
• API's GUI support for applications
• Kernel
• Core of operating system
• Manages hardware, memory
• Enables multitasking
• Configuration data
• h/w s/w information
• user preferences
• s/w settings, etc.
• for O/S at boot, user, and applications

Configuration data Registry, .ini/inf files
shell
Kernel or Core
hardware
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Terminology

• Threads
• Processes that are running on a computer
• Multitasking
• Ability to run multiple threads "at the same
  time"
• On-demand multitasking
• O/S interrupts app on timeslice, h/w request
• Runs another thread
• Apps don't see interruption

• 16-bit, 32-bit, 64-bit
• Size of a "word"
• Bigger word
• More data processed at a time
• Handles more memory
• File structures
• FAT16, FAT32, NTFS, etc.
• How data is organised on drives
• Determines management capabilities, drive size,
  efficiency, etc.

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O/S'sDOS (disk operating system)

• First O/S used by IBM PC's
• Simple, reliable troubleshooting tool
• Useful when complex O/S fails
• Windows 3.x was GUI shell to DOS
• Windows 9x has some DOS programs

• Pros
• Small footprint, no GUI overhead,
• Legacy, specialised/unattended environment
• Cons
• Memory management limited/awkward
• Cryptic user interface
• No multitasking
• No inherent networking support
• No apps being written for it.

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O/S'sWindows 9X (95, 98, 98SE, ME)

• GUI interface support
• Object-oriented concept
• Plug-and-play
• h/w discovery config
• 32-bit core
• 16-bit support
• Memory paging, multitasking
• Fundamental DOS core

• Pros
• User-friendly, intuitive GUI
• Backward-compatible to DOS, Windows 3.x
• Old/new h/w s/w support
• Multitasking
• Cons
• Backward-compatible with DOS
• Limitations failures
• No longer supported

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98SE ME

• 98SE
• SE second edition
• Patches on 98
• Improved networking
• ICS internet connection sharing

• ME
• Actually 98TE
• More NT technology
• Multimedia support
• Video/digital cameras, scanners, etc.
• Video compression
• System restore-points
• Students didn't find it reliable or
  backward-compatible enough

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O/S'sWindows NT/2000/XP/2003

• IBM Microsoft collaborated on development
• "New Technology"
• Abandon architectural limitations of DOS
• 32-bit architecture
• HAL hardware abstraction layer
• Control access to protect hardware/memory
• Multi-platform support (abandoned with 2000)
• New memory management, file structures, etc
• Legacy support controlled environment, 16-bit
  emulation
• Only if don't try to access hardware directly
• Isolated threads, less likely to hang
• Designed as a server architecture, with
  networking/multitasking in core
• Competition to Novell's NetWare
• IBM/Microsoft split 1993
• IBM introduced OS/2
• Microsoft introduced NT

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O/S'sWindows NT

• 1994 2000 v4 last
• Multiprocessing (multiple CPU's)
• Designed for network support
• But could run desktop apps (marketing)
• Central directory
• Limited, but useful
• File/folder security access control

• Pros
• Target client/server
• New file system NTFS
• Pro version networking authentication over LAN
• File security
• Cons
• Higher h/w requirements
• s/w incompatibilities
• No PnP
• Replaced not supported

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O/S'sWindows 2000/2003

• Improved Active Directory
• PnP
• Improved reliability
• System file protection
• Improved security in file system
• Logon encryption
• Notebook support
• Power management
• Offline files
• Secure communications

• Pros
• Advanced security
• Centralised control via Active Directory
• Multiple versions
• Depends on use
• Cons
• Higher h/w requirements
• Not scalable separate versions
• 2000 replaced by 2003, but still supported

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Windows 2003 versions

• XP Pro (replaces 2000 Pro)
• Desktop version
• max 10 client connections
• 2 CPUs
• Web Edition
• Focused on web, .NET, ASP
• lacks other common services
• 2 CPUs, 2GB memory, 32-bit processors
• Standard Edition
• Small/med companies
• 2 CPUs, 4GB memory, 32-bit processors

• Enterprise Edition
• Server clustering
• Data replication
• Load balancing
• Bypass downed server
• 8 CPUs, 32/64GB memory, 32/64-bit processors
• Datacenter Edition
• 8-32 CPUs, 64/128GB memory, 32/64-bit processors

Note XP Home edition no IIS, cannot join a
Windows 2000/2003 domain.
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O/S'sWindows XP

• Replaces NT Pro, 2000 Pro desktop versions
• Pre-release 2003 version
• Replacing all previous desktop versions
• Editions
• Home
• Pro
• Remote access, join 2000 domain, IIS, roaming
  profiles
• Media Centre
• Pro multimedia formats
• Tablet
• Pro touch-screen, writing interpretation, etc.
• 64-bit
• AMD Opteron or Intel Itanium technical
  workstations

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O/S'sUNIX

• Written in 1968-1970
• C-based
• Device independent everything is a file
• Available for any platform with a C compiler
• Multitasking, multiuser, networking
• Basis of original design
• Powerful, reliable Internet servers
• Excellent database server

• Pros
• Strong multi-processing
• Large memory management
• Great for networking
• Less memory/processing requirements
• Doesn't crash
• Remote management
• telnet, SSH, FTP
• Cons
• Requires powerful machines
• Fewer business applications
• Command-prompt oriented
• Less app development web publishing apps

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O/S'sLinux

• Unix alternative for smaller platforms
• Server
• Desktop
• Open source
• Downloadable for free
• Depends on s/w community for enhancements
• Customisable
• Distributions
• Variations sold by s/w companies
• Differ in support facilities
• Tools
• Vendor support

• Pros
• Rarely crashes
• Basic versions free
• Distros available with support
• Customisable
• Less computing power required
• Excellent network facilities
• DHCP, DNS, web, e-mail
• Cons
• Can be clumsy to install
• Documentation spotty
• Optimising takes time
• Experts thin on ground
• Expensive
• Fewer business applications
• Less "familiar"
• Fewer integrated development packages

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O/S'sOS/2

• IBM Microsoft collaboration
• Features similar to Windows NT
• Esp. server support
• Still used by ticketing systems, banks,
  railroads, US gov't, etc.
• Didn't catch on with public

• Pros
• More efficient than Windows, esp. for DOS apps
• Large memory management
• Icon interface
• Good for networking
• OS/2-designed s/w runs better that Windows equiv.
• Cons
• Few apps written for it
• Unpopular/unfamiliar
• Market not growing
• Rumours of terminal illness
• Still supported
• But IBM would like out

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O/S'sMac OS

• Only for Mac computers
• Designed around graphical environment
• Easy to use
• Windows icons
• Popular for education
• Great graphics support
• Good for gaming
• Good for graphics design
• Multitasking, PnP
• Proprietary
• O/S locked in, API's h/w specs concealed
• Few secondary vendors
• No economies of scale

• Pros
• Excellent interface
• GUI, PnP since inception
• Large memory management
• Many graphics, web multimedia applications
• Less prone to crashing
• Lower maintenance costs
• Cons
• Not viewed as a high-powered business computer
• Being supplanted in graphics realm by
  higher-powered Windows machines
• s/w apps not always available.
• Less market share
• Mac X is UNIX

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What O/S does for you How it interacts with
hardware
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BIOSBasic Input/Output System

• Startup BIOS is a program to
• Start the computer
• Search for load O/S
• Configure CMOS
• System BIOS programs to manage simple devices
• Floppy disk drives
• Keyboard
• Hard drives (occasionally)
• Support for
• Advanced Configuration and Power Interface (APCI)
• previously Advanced Power Management (APM)
• Plug and Play (PnP)

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PnPautomatic discovery and assignment of
resources to hardware devices most motherboards
since 1994

• BIOS and O/S must both support PnP
• BIOS begins config process
• Device discovery
• Assign next-available resource
• O/S uses BIOS data to complete config
• Win 9x
• Supports PnP
• Win NT
• Doesn't support PnP
• Still manually assign IRQ, memory I/O
  addresses, DMA channels
• Win 2000/XP/2003
• More advanced PnP
• Doesn't use BIOS's data
• Ms suggests disabling BIOS PnP

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O/S facilities

• Manage user interface
• Manage files and folders
• Manage applications
• Manage hardware

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O/S Managing Files and Folders

• Physical disk organisation
• Circular tracks divided into 512-byte sectors
• Sectors grouped into clusters
• Smallest addressable unit on drive
• Size depends on format
• Partitions
• MBR master boot record 1 per physical drive
• Carries partition information, pointer to boot
  drive
• Max 4 partitions
• 1-4 primary partitions (1 logical drive each)
• Max 1 extended partition (several logical drives)
• Root directory
• Created in format process
• Each logical drive has its own root directory
• Contains files and subdirectories
• Subdirectories can themselves contain files and
  other subdirectories

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O/S Managing Applications

• O/S loads runs programs
• O/S provides (controls)
• Access to hardware
• Management of data in memory
• Make virtual memory appear "real"
• Management of secondary storage
• Hard drive, zip, CD
• Application makes resource requests to O/S

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Loading applications

• Shortcut icon
• Visual stand-in for command line
• Can modify execution environment
• Start menu
• Most installed executables listed in menu
  structure
• Run command
• Type commands and execution parameters
• Windows Explorer
• Locate command on drive, double-click to execute
• Note data files
• File extension identifies the application to be
  executed for this file (Microsoft)

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Real (16-bit) Protected (32-bit) Modes

• Real mode
• Applications have full access to hardware
• Simulated in NT/2000
• Using a protected-mode shell
• Which is why many 16-bit apps don't work
• 16-bit drivers loaded via config.sys,
  autoexec.bat, system.ini
• Protected mode
• O/S controls application's access to hardware
• More than 1 program can run
• Applications protected from each other
• CPU starts in real mode
• O/S shifts it into protected mode
• Pre-emptive Multitasking
• O/S allots CPU time to applications
• Gives CPU to another application when
• App exceeds allotted timeslot
• App makes a call to hardware or memory

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Virtual real mode 9x

• Windows 9x later don't really permit direct
  access to hardware
• It simulates a 16-bit environment
• Runs all 16-bit apps in the one space
• 32-bit manager ensures apps don't "leak" out

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Virtual real mode NT

• Windows NT/2000 don't permit direct access to
  hardware
• NTVDM NT virtual DOS Machine
• Runs as a shell
• Provides a protected environment for 16-bit apps

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O/S Managing Hardware

• O/S doesn't interact directly w/ hardware
• Uses device drivers or system BIOS
• Device drivers
• Small programs on hard drive
• Written to understand specific hardware
• Written to interface with O/S API (hooks)
• Usually O/S-specific
• System BIOS
• Contains drivers for devices/interfaces on
  motherboard
• Common keyboard floppy drive
• Usually O/S-independent
• XP uses its own drivers, thank you.

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Device Drivers

• Designed to interface with specific hardware
• Some come with O/S
• standardised/approved/common drivers
• Some provided by hardware manufacturer
• Specific to an O/S
• Provided with hardware device
• Available over Internet
• See instructions
• Frequently, install hardware and then driver
• Occasionally, install driver and then hardware
• Note Win 2000/XP
• Check hardware compatibility list
• www.microsoft.com/whdc/hcl/search.mspx
• Check compatibility on box or manufacturer's site
• Later drive may be available than shipped with
  Windows

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Windows 9x 16-bit drivers

• Older equipment, no 32-bit drivers
• Cannot load to NT/2000/XP/2003
• Can use 16-bit real-mode driver in Win 9x
• Loaded by entries in
• Config.sys
• Autoexec.bat
• System.ini
• Old term terminate-and-stay-resident (TSR)
• Driver loaded at boot, stays in memory in case
  needed

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System BIOS

• Programs for interfacing w/ simple devices
• Keyboards, floppy drives, serial ports, etc.
• Can be used to access hard drive
• May cause problems when going past 20GB drive
• Better to use device driver (faster)
• Check CMOS setup
• Or control panel?system?device manager
• To see which you're using
• eg no config settings for Zip DVD drives

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Device Manager

• Used to manage h/w devices and their drivers
• Windows 2000/XP
• My Computer?properties?hardware tab
• Windows 9x
• My Computer?properties?device manager tab
• Open each category to see device(s)
• Select Properties on device to see/update driver
• Different views
• Can see system resource assignments

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System Information

• Device Manager info plus more
• BIOS version
• Where O/S is installed
• Driver other software info
• Run msinfo32.exe
• DOS/Win 9x
• Also had MSD.exe

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msinfo32.exe