原创 Laptop Boot theory

Laptop Boot  theory
laptop boot process is divided into Hard reboot and Soft reboot. A hard reboot (also known as a cold reboot, cold boot or cold start) is when power to a computer is cycled.A soft reboot (also known as a warm reboot) is restarting a computer under software control, without removing power or (directly) triggering a reset line. It usually, though not always, refers to an orderly shutdown and restarting of the machine.it is helpful to research laptop boot theory for repair laptop motherboard. especially the laptop motherboard is alway crash.

this picture show the process of the laptop hard reboot.

hardreboot

Under the normal, PS-ON of power connector is in high level. only if the PS-ON is in low level.the power connector will start up to work.under the normal,SUSC# of South bridge must be in high level,because it is effective when this Signal must  in low level.In these cases ,the base of  dynatron is low level. dynatron cut-off,5V-SB is direct connected to PS-ON.the power maintain normal and can not send PG singnal to south bridge.the laptop system cann’t start up.Conversely,POWER BUTTON BOARD is work,SUSC# is in low level,5V-SB Conductive earth.PS-ON is in low level. POWER send PG singnal to south bridge ,NOTTHBRIDGE and CPU;
when South bridge received the PG singnal  and CLOCK singnal that from CLOCK GENERATION,it is start to work.than it send RESET# to ISA,PCI,AGP bus.
when north bridge receive PG,PCI,RESET#and CLOCK singnal than send correst# to CPU.
CPU receive correst# singnal  to work and send FFFFFFF0 address to Bios.the hard reboot is end. Bios start to saft boot.

regarding saft boot,We will tell more aBout this on tomorrow’s “laptop boot theory (2)”,Don t forget to continue to watch our blog.

soft boot is BIOS(Base Input Output System) start to POST(Power On Self Test)
when CPU working,following is the distribution of upper memory.
A0000…BFFFF: VIDEO MEMORY
C0000…C7FFF: VGA BIOS
C8000…CFFFF: I/O ROM
D0000…DFFFF Optional ROM & Buffer Area
E0000…FFFFF:BIOS
the picture show the process of soft boot

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