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Transcript 
The Basic Components
Booting Up 1
Bootstrap
CMOS
basic boot parameters (boot
device ID, boot sector
location and size, etc.) stored
in low-power memory
loaded from
sector 0 of boot
device; loads
more
sophisticated
loader program
RAM
Bootstrap
Loader
OS
Loader
loads OS kernel
from boot device
ROM
POST
BIOS
Power-On Self-Test
fundamental hardware
checks before any
other software is
installed
Boot Device
Basic I/O System
knows just
enough to
perform
necessary data
transfers
Computer Science Dept Va Tech Jan 2008
Operating Systems
©2003-08 McQuain
Data Flow
Booting Up 2
RAM
Boot Device
Bootstrap
ROM
Loader
POST
OS
BIOS
CMOS
Computer Science Dept Va Tech Jan 2008
Operating Systems
©2003-08 McQuain
The Hardware Process
Booting Up 3
RAM
Boot Device
Bootstrap
ROM
Power Up
Loader
POST
OS
BIOS
CMOS
Computer Science Dept Va Tech Jan 2008
Operating Systems
©2003-08 McQuain
Bootstrap Program
FIXED_LOC:
Booting Up 4
# bootstrap loader entry point
load
R1, =0
load
R2, =LENGTH_OF_TARGET
# next instructions copy a block from BOOT_DISK to memory:
read
loop: load
BOOT_DISK, BUFFER_ADDRESS
R3, [BUFFER_ADDRESS, R1]
store
R3, [FIXED_DEST, R1]
incr
R1
bleq
R1, R2, loop
br
FIXED_DEST
Computer Science Dept Va Tech Jan 2008
Operating Systems
©2003-08 McQuain
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