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Chapter 2. How Hardware and Software Work Together. You Will Learn…. How hardware and software interact How system resources help hardware and software communicate How an OS relates to BIOS, device drivers, and applications Different ways an OS can launch applications.

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Chapter 2

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Chapter 2

How Hardware and Software Work Together


You Will Learn…

  • How hardware and software interact

  • How system resources help hardware and software communicate

  • How an OS relates to BIOS, device drivers, and applications

  • Different ways an OS can launch applications


Hardware and Software Interaction: An Overview


Software

  • The intelligence of the computer

  • Determines what hardware is present

  • Decides how it is configured and used

  • Uses hardware to perform tasks


Operating System (OS)

  • Controls hardware components that make up a computer

  • Provides an interface for users


Functions of an OS

  • Uses BIOS

  • Manages secondary and primary storage

  • Helps diagnose problems with hardware and software

  • Interfaces between hardware and software

  • Performs tasks the user requests


DOS

Windows 9x

Windows NT, Windows 2000, and Windows XP

Unix

Linux

OS/2

Mac OS

Available Operating Systems


Categories of PC Software

  • BIOS and device drivers

  • Operating system

  • Application software


Categories of PC Software


System Resources


System Bus Components


The 8-Bit and 16-Bit ISA Slots

  • 8-bit ISA bus

    • Older bus used on early PCs (1980s)

    • Had eight lines for data

  • 16-bit

    • Provide more memory addresses, DMA channels, and IRQs


8-Bit ISA Bus


16-Bit ISA Bus


Interrupt Request Number (IRQ)

  • Line on a bus that a device needing service uses to alert the CPU

  • COM and LPT are preconfigured assignments of system resources that a device can use


IRQ Numbers


Second Interrupt Controller Chip on 16-Bit ISA Bus


How IRQs Are Assigned


Accessing Device Manager to View System Resources


Memory Addresses

  • Number assignments for memory locations

  • Hexadecimal numbers, often written in segment:offset form, assigned to RAM and ROM so that the CPU can access both

  • Example: C800:5, which is 819,205 in decimal


Memory Addresses


How the CPU Communicates Memory Addresses


Division of Memory Under DOS


Assigning Memory Addresses


Shadowing ROM

  • Process of copying programs from ROM to RAM for execution


I/O Addresses

  • Numbers the CPU can use to access hardware devices

  • Also called port addresses or ports


I/O Addresses


IRQs and I/O Addresses

continued…


IRQs and I/O Addressesfor Devices


DMA Channels

  • Provide a shortcut for a device to send data directly to memory, bypassing the CPU


How an OS Relatesto Other Software

  • All interaction between software and hardware is by way of the CPU

  • CPU operates in two modes:

    • 16-bit (real mode)

    • 32-bit (protected mode)

  • OS must use same mode the CPU uses


Real (16-Bit) and Protected (32-Bit) Operating Modes

  • Real mode

    • Single-tasking

    • 16-bit data path; 1 MB of memory addresses

  • Protected mode

    • Multitasking

    • 32-bit data data path; at least 4 GB of memory addresses

    • OS manages access to RAM and does not allow a program direct access to it


Real Mode


Protected Mode


Real Mode and Protected Mode Compared


How an OS Uses Real and Protected Modes

  • OS must be in sync with the CPU

  • Applications must be compiled to run in either real or protected mode

  • Hybrid of real and protected mode used by older software written for Windows 3.x


General Types of Software That Run on PCs

  • 16-bit DOS software

    • Designed to run in real mode as only program running and expecting direct access to hardware

  • 16-bit Windows software

    • Designed for Windows 3.x to run where other programs might also be running

  • 32-bit Windows software

    • Designed to run in protected mode with other software and can be loaded into extended memory


How an OS Uses System BIOS

  • Contains programming instructions to run simple hardware devices (eg, keyboard and floppy disk drive)

  • Can be used to access the hard drive

  • Stored on ROM chips


How an OS Uses System BIOS


How an OS Uses System BIOS


How Device Drivers Control Hardware

  • Stored on the hard drive

  • Usually written for a particular OS


Device Drivers


Device Drivers


Windows 9x Device Drivers


Device Drivers underWindows 2000

  • Uses only 32-bit drivers


How an OS Launches Applications

  • Applications depend on an OS to:

    • Provide access to hardware resources

    • Manage its data in memory and secondary storage

    • Perform many background tasks


Loading Application Software Using the Windows Desktop

  • From the Start menu

  • Shortcut icon on the desktop

  • Run dialog box

  • Windows Explorer or My Computer


Using a Shortcut Icon


Using the Run Dialog Box to Execute Software


Chapter Summary

  • How operating system software controls several significant hardware devices

  • How an OS provides the interface that applications need to command and use hardware devices


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