1. How Hardware and Software Work Together
Chapter 2
How Hardware and Software Work Together

2. You Will Learn…
About operating systems, what they are, and what they do
How an OS interfaces with users, applications, and hardware
How system resources help hardware and software communicate
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3. Introducing Operating Systems
Software that controls a computer
Acts as a middleman between applications and hardware
Two main internal components
Shell
Kernel
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4. OS as a Middleman
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5. The Shell and the Kernel
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6. Common Operating Systems
DOS
Windows 9x
Windows NT, Windows 2000, and Windows XP
Unix
Linux
OS/2
Mac OS
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7. What an Operating System Does
Provides user interface
Stores, retrieves, and manipulates files and folders
Manages applications
Manages hardware
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8. How an OS Provides a User Interface
Command-driven interfaces
Menu-driven interfaces
Icon-driven interfaces
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9. A Menu-Driven Interface
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10. How an OS Manages Files and Folders
Uses file system (FAT or NTFS) to track how clusters are used for each stored file
Uses directories, subdirectories, and files
Uses partitions and logical drives on hard drive
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11. Tracks, Sectors, and Clusters
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12. Files and Directories
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13. Partitions and Logical Drives
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14. How an OS Manages Applications
Provides access to hardware resources
Manages data in memory and in secondary storage
Performs other background tasks
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15. Loading Application Software Using the Windows Desktop
Shortcut icon
Start menu
Run command
Windows Explorer or My Computer
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16. Using a Shortcut Icon to Load Software
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17. Real and Protected Operating Modes
Real (16-bit) operating mode
CPU processes 16 bits of data at one time
Software has “real” access to hardware
Protected (32-bit) operating mode
CPU processes 32 bits of data at one time
More than one program can be running, each one “protected” from others
Uses preemptive multitasking
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18. 16-Bit and 32-Bit Software 16-bit software 32-bit software
Written for Windows 3.x
Accesses data 16 bits at a time
Programs should not infringe on resources of other programs that are running
32-bit software
Written for Windows 95 and later Windows OSs
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19. How an OS Manages Hardware
Uses device drivers or the BIOS (system BIOS, startup BIOS, or CMOS setup) to interface with hardware
Trend is to manage devices with device drivers rather than BIOS
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20. How an OS Manages Hardware (continued)
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21. How an OS Uses Device Drivers to Manage Hardware
Device drivers provide OS with software necessary to control devices
16-bit read-mode drivers
Supported by Windows 95/98
32-bit protected-mode drivers
Supported by Windows 95/98, Windows Me, and Windows NT/2000/XP
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22. How an OS Uses System BIOS to Manage Devices
To communicate with simple devices (eg, floppy drives or keyboards)
To access the hard drive
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23. Using System BIOS
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24. Using System BIOS (continued)
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25. System Resources
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26. System Resources (continued)
Depend on certain lines on a bus on motherboard
System bus components
Data bus carries data
Address bus communicates addresses (memory addresses and I/O addresses)
Control bus controls communication (IRQs and DMA channels)
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27. System Bus Components
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28. Interrupt Request Number (IRQ)
Line on a bus that device needing service uses to alert the CPU
Managed by interrupt controller on motherboard
Early motherboards: eight IRQs
Second group of IRQs and second interrupt controller have been added to accommodate need for more devices
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29. Common Assignments for First Eight IRQs
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30. Second IRQ Controller
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31. Viewing IRQ Assignments
Microsoft Diagnostic Utility (MSD) for DOS
Device Manager for Windows 2000/XP and Windows 9x
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32. Viewing IRQ Assignments (continued)
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33. Viewing IRQ Assignments (continued)
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34. Memory Addresses
Hexadecimal numbers assigned to RAM and ROM so the CPU can access both
Used to access physical memory
Often written in segment:offset form (eg, C800:5)
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35. Memory Addresses (continued)
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36. I/O Addresses Numbers CPU can use to access hardware devices
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37. I/O Addresses (continued)
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38. Common Assignments for I/O Addresses
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39. Direct Memory Access (DMA) Channels
Shortcut method that lets an I/O device send data directly to memory, bypassing the CPU
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40. DMA Channels
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41. OS Tools to Examine a System
Device Manager
System Information utility
Microsoft Diagnostic Utility (MSD)
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42. Device Manager
Primary tool used to manage hardware devices under Windows 2000/XP and Windows 9x
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43. Device Manager ( continued)
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44. System Information Utility
Gives similar, but more, information than Device Manager
BIOS version in use
Directory where OS is installed
How system resources are used
Information about drivers and their status
Additional information about software
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45. Using Windows System Information
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46. Microsoft Diagnostic Utility (MSD)
Useful for viewing information about the system, including:
Memory
Video
Ports
Device drivers
System resources
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47. Using MSD
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48. Summary How hardware and software work together
Different operating systems
What they do
How they work to control hardware devices
How an OS provides the interface that users and applications need to command and use hardware devices
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