User manual

B-3

Appendix B: BIOS POST Checkpoint Codes

Checkpoint Code Description

03h The NMI is disabled. Next, checking for a soft reset or a power on condition.

05h The BIOS stack has been built. Next, disabling cache memory.

06h Uncompressing the POST code next.

07h Next, initializing the CPU and the CPU data area.

08h The CMOS checksum calculation is done next.

0Ah The CMOS checksum calculation is done. Initializing the CMOS status register for date and

time next.

0Bh The CMOS status register is initialized. Next, performing any required initialization before the

keyboard BAT command is issued.

0Ch The keyboard controller input buffer is free. Next, issuing the BAT command to the keyboard

controller.

0Eh The keyboard controller BAT command result has been veriﬁ ed. Next, performing any neces-

sary initialization after the keyboard controller BAT command test.

0Fh The initialization after the keyboard controller BAT command test is done. The keyboard com-

mand byte is written next.

10h The keyboard controller command byte is written. Next, issuing the Pin 23 and 24 blocking and

unblocking command.

11h Next, checking if <End or <Ins> keys were pressed during power on. Initializing CMOS RAM

if the Initialize CMOS RAM in every boot AMIBIOS POST option was set in AMIBCP or the

<End> key was pressed.

12h Next, disabling DMA controllers 1 and 2 and interrupt controllers 1 and 2.

13h The video display has been disabled. Port B has been initialized. Next, initializing the chipset.

14h The 8254 timer test will begin next.

19h Next, programming the ﬂ ash ROM.

1Ah The memory refresh line is toggling. Checking the 15 second on/off time next.

2Bh Passing control to the video ROM to perform any required conﬁ guration before the video ROM

test.

2Ch All necessary processing before passing control to the video ROM is done. Looking for the

video ROM next and passing control to it.

2Dh The video ROM has returned control to BIOS POST. Performing any required processing after

the video ROM had control

23h Reading the 8042 input port and disabling the MEGAKEY Green PC feature next. Making the

BIOS code segment writable and performing any necessary conﬁ guration before initializing the

interrupt vectors.

24h The conﬁ guration required before interrupt vector initialization has completed. Interrupt vector

initialization is about to begin.

B-3 Uncompressed Initialization Codes

The following runtime checkpoint codes are listed in order of execution.

These codes are uncompressed in F0000h shadow RAM.