Table of Contents
Advertisement
E.4
POST CODES
NOTE
EISA POST codes are typically output to port address 300h. ISA
POST codes are output to port address 80h.
POST Codes
POST
Name
(hex)
CO
Turn Off Chipset Cache
1
Processor Test 1
2
Processor Test 2
3
Initialize Chips
4
Test Memory Refresh Toggle
5
Blank video,
Initialize keyboard
6
Reserved
7
Test CMOS Interface and
Battery Status
BE
Chipset Default Initialization
C1
Memory presence test
C5
Early Shadow
C6
Cache presence test
8
Setup low memory
9
Early Cache Initialization
A
Setup Interrupt
Vector Table
B
Test CMOS RAM Checksum
C
Initialize keyboard
Description
OEM Specific-Cache control
Processor Status (1FLAGS) Verification.
Tests the following processor status flags: Carry, zero, sign, overflow.
The BIOS will set each of these flags, verify they are set, then turn each
flag off and verify it is off.
Read/Write/Verify all CPU registers except SS, SP, and BP with data
pattern FF and 00.
Disable NMI, PIE, AIE, UEI, SQWV.
Disable video, parity checking, DMA.
Reset math coprocessor.
Clear all page registers, CMOS shutdown byte.
Initialize timer 0, 1, and 2, including set EISA timer to a known state.
Initialize DMA controllers 0 and 1.
Initialize interrupt controllers 0 and 1.
Initialize EISA extended registers.
RAM must be periodically refreshed in order to keep the memory from
decaying. This function assures that the memory refresh function is
working properly.
Keyboard controller initialization.
Verifies CMOS is working correctly, detects bad battery.
Program chipset registers with power on BIOS defaults.
OEM Specific-Test to size on-board memory.
OEM Specific-Early Shadow enable for fast boot.
External cache size detection.
Early chip set initialization.
Memory presence test.
OEM chip set routines.
Clear low 64K of memory.
Test first 64K memory.
Cyrix CPU initialization.
Cache initialization.
Initialize first 120 interrupt vectors with SPURIOUS_INT_HDLR and
initialize INT 00h-1Fh according to INT_TBL.
Test CMOS RAM Checksum, if bad, or insert key pressed, load
defaults.
Detect type of keyboard controller (optional).
Set NUM LOCK status.
E-5
BIOS Setup Error Codes
Advertisement
Table of Contents
