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Software and Hardware
working together
BIOS Startup Program checks hardwareto make sure it is ready to be used
User provides specific instructions tosoftware on what to do
Software interacts directly with the CPU,
which controls the various underlyingmechanisms that make the computerwork as intended
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System Resources Defined
A tool used for communication betweenhardware and software
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The Boot Process
Functions performed Startup BIOS tests essential hardware
components (power-on self test [POST])
Setup information is used to configure bothhardware and software
Hardware components are assigned systemresources they will later use for communication
OS is loaded, configured, and executed Hardware devices are matched up with BIOS and
device drivers that control them
Some applications software may be loaded and
executed
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The Boot Process, Step by Step
Step 1: Power-on self test (POST)
Step 2: The ROM BIOS startup
program searches for and loads an OS
Step 3: The OS configures the systemand completes it own loading
Step 4: The user executes applicationssoftware
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Step 1: POST
The ROM BIOS startup program surveyshardware resources and needs, and assigns
system resources to meet those needs Begins by reading configuration information
stored in DIP switches, jumpers, and theCMOS chip and comparing that information to
the hardware present
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Step 1: POST
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Step 2: BIOS Finds and Loads
the OS
Most often the OS is loaded from logical driveC on the hard drive (Figure 2-4)
Configuration information on the CMOS chiptells startup BIOS where to look for the OS(Figure 2-5)
BIOS turns to that device, reads thebeginning files of the OS, copies them intomemory, then turns control over to the OS
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Step 2: BIOS Finds and Loads
the OS
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Step 2: BIOS Finds and Loads
the OS
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Step 3: The OS Completes the
Boot Process
The OS checks some of the samethings that startup BIOS checked (e.g.,
available memory and whether memoryis reliable)
The OS loads software to control the
mouse, a CD-ROM, a scanner, andother peripheral devices (generally havedevice drivers)
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Step 3: The OS Completes the
Boot Process
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Step 4: User Executes
Applications Software
The OS finds the applications software (on asecondary storage device) copies software
into memory, and turns control over to it User commands the applications software,
which makes requests to the OS, which usesthe system resources, system BIOS, and
device drivers to interface with and controlthe hardware
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Completion of the Boot Process
Boot process is completed afterAUTOEXEC.BAT has finished
executing In Windows 3.x, it is common to include
in AUTOEXEC.BAT the followingcommand to execute Windows eachtime the computer is booted:
C:\WINDOWS\WIN
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How Software Manages
Hardware Resources
System resources IRQs
I/O addresses Memory addresses
DMA channels
System resources are dependent oncertain lines on a bus on the systemboard
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The 8-bit and 16-bit ISA Bus
8-bit ISA bus An older bus used on early PCs of 1980s
Had eight lines for data 16-bit
8 additional data lines
5 additional IRQ lines 4 more DMA channels
4 additional address lines
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8-bit ISA bus
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16-bit ISA bus
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Interrupt Request Number
(IRQ)
Hardware interrupt
An event caused by a hardware device
signaling the CPU that it requires service
Interrupt request number (IRQ)
A line on a bus that is assigned to a device
and is used to signal the CPU for servicing
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Interrupt Request Numbers
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Interrupt Request Numbers
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Interrupt Request Numbers and
I/O Addresses for Devices
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Protecting Data, Software, and
Hardware
Saving and restoring setup informationin CMOS
Keeping OS rescue disks
Backing up the hard drive
Documentation
Damage from electricity
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Saving and Restoring Setup
Information in CMOS
Two common utility software programsfor backing up setup information to a
disk to be used to recover lost setupinformation
Nuts & Bolts
Norton Utilities
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Saving Setup Information Using
Nuts & Bolts
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Saving Setup Information Using
Nuts & Bolts
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Saving Setup Information Using
Norton Utilities
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Saving Setup Information Using
Norton Utilities
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Saving Setup Information Using
Norton Utilities
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Keeping OS Rescue Disks
Allows you to boot a computer
Essential for every computer
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Backing Up Your Hard Drive
Backup
An extra copy of a file or files made to a
different location or storage media
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Documentation
Keep hardware and softwaredocumentation well labeled in a safe
place
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Damage from Electricity
Computers and data can be destroyed by twokinds of electricity Static electricity (ESD or electrostatic discharge)
Power spikes, including lightning
Practical protection against damage Never touch the inside of a computer when it is
turned on
Be grounded when computer is on
Use devices for protection against electricalsurges and lightning
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Chapter Summary
How individual computer componentswork together to perform tasks