BIOS POST Checkpoints E-3
Table E-1 POST Checkpoint List
Checkpoint Description
74h
• Serial port testing
78h
• Math coprocessor testing
7Ch
• Reset pointing device
80h
• Set security status
84h
• KB device initialization
• Set KB led upon setup requests
• Enable KB device
86h
• Issue 2nd software SMI to communicate with PMU
• Enable the use of BIOS Setup, system information. and fuel gauge
6Ch
• Tests and initializes FDD
Note: The FDD LED should flash once and its head should be positioned.
6Dh
• password checking
88h
• HDD, CD testing & parameter table setup
• Initializes HDD, CD enhanced features
90h
• Displays POST status if necessary
• Changes POST mode to default text mode
94h
• Initializes I/O ROM
Note: I/O ROM is an optional extension of the BIOS located on an installed add-on
card as a part of the I/O subsystem. POST detects I/O ROMs and gives them
opportunity to initialize themselves and their hardware environment.
• Shadows I/O ROM if setup requests
• Builds up free expansion ROM table
96h
• Initializes PCI Card ROM
• Writes ESCD data into NVRAM
97h
• Writes ESCD data into NVRAM
A0h
• Initializes timer counter for DOS use
A4h
• Initializes security feature
ACh
• Enables NMI
• Enables parity checking
• Sets video mode
AEh
• Issues 3rd software SMI to communicate with PMU
• Starts all power management timers
• Checks whether system is resumed from 0V suspend or not.
B0h
• Clear memory buffer used for POST
• Select boot device
BDh
• Shutdown 5
BEh
• Shutdown A
BFh
• Shutdown B
