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E-2 Service Guide
Table E-1 POST Checkpoint List
Checkpoint Description
23h
• Detects whether keyboard u is depressed from system powered-on till POST or not. If
yes, set BIOS Setup parameter too default settings; or keep the original settings.
24h
• Tests programmable interrupt controller (8259)
• Initializes system interrupt
30h
• Enables system shadow RAM
34h
• Memory sizing
5Ah
• Changes SMBASE, copy SMI Handler.
•
56h
• Issues 1st software SMI to communicate with PMU.
• Initializes the SMI environment.
3Fh
• Enable/Disable USB function
3Ch
• Initializes interrupt vectors
3Eh
• Set fixed CMOS setting
4Ch
• CPU clock checking
• Sets the DRAM timing in correspondent to the system speed
35h
• Scans PCI Devices to Initialize the PCI buffer that used by BIOS.
4Eh
• Isolations for PnP ISA Card
4Fh
• Configurations for PnP ISA Card
• Initializes the PCI device according to ESCD data (if ESCD data is valid).
• Initialize the PCI Devices by BIOS
• Initialize the PCI VGA card
50h
• Initializes video display
Note: If system has any display card, here it should be initialized via its I/O ROM or
corresponding initialization program.
Exh
• VGA BIOS POST.
54h
• Enables video shadow RAM
58h
• Displays Acer (or OEM) logo (if necessary)
• Displays Acer copyright message (if necessary)
• Displays BIOS serial number
5Ch
• Memory testing
5Eh
• Assign PCMCIA resource, enable serial IRQ
60h
• External Cache sizing
• Enables/disables L1/L2 cache according to the BIOS SETUP
64h
• Tests keyboard interface
Note: The keyboard LEDs should flash once.