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Chapter 2

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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  1. Chapter 2 How Hardware and Software Work Together

  2. 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

  3. Hardware and Software Interaction: An Overview

  4. Software • The intelligence of the computer • Determines what hardware is present • Decides how it is configured and used • Uses hardware to perform tasks

  5. Operating System (OS) • Controls hardware components that make up a computer • Provides an interface for users

  6. 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

  7. DOS Windows 9x Windows NT, Windows 2000, and Windows XP Unix Linux OS/2 Mac OS Available Operating Systems

  8. Categories of PC Software • BIOS and device drivers • Operating system • Application software

  9. Categories of PC Software

  10. System Resources

  11. System Bus Components

  12. 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

  13. 8-Bit ISA Bus

  14. 16-Bit ISA Bus

  15. 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

  16. IRQ Numbers

  17. Second Interrupt Controller Chip on 16-Bit ISA Bus

  18. How IRQs Are Assigned

  19. Accessing Device Manager to View System Resources

  20. 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

  21. Memory Addresses

  22. How the CPU Communicates Memory Addresses

  23. Division of Memory Under DOS

  24. Assigning Memory Addresses

  25. Shadowing ROM • Process of copying programs from ROM to RAM for execution

  26. I/O Addresses • Numbers the CPU can use to access hardware devices • Also called port addresses or ports

  27. I/O Addresses

  28. IRQs and I/O Addresses continued…

  29. IRQs and I/O Addressesfor Devices

  30. DMA Channels • Provide a shortcut for a device to send data directly to memory, bypassing the CPU

  31. 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

  32. 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

  33. Real Mode

  34. Protected Mode

  35. Real Mode and Protected Mode Compared

  36. 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

  37. 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

  38. 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

  39. How an OS Uses System BIOS

  40. How an OS Uses System BIOS

  41. How Device Drivers Control Hardware • Stored on the hard drive • Usually written for a particular OS

  42. Device Drivers

  43. Device Drivers

  44. Windows 9x Device Drivers

  45. Device Drivers underWindows 2000 • Uses only 32-bit drivers

  46. 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

  47. Loading Application Software Using the Windows Desktop • From the Start menu • Shortcut icon on the desktop • Run dialog box • Windows Explorer or My Computer

  48. Using a Shortcut Icon

  49. Using the Run Dialog Box to Execute Software

  50. 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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