Appendix B: Post Codes - Gigabyte GA - 586STX User Manual

APPENDIX B: POST CODES

F
EISA POST codes are typically output to port address 300h. ISA POST
codes are typically output to port address 80h.
POST Name
C0 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
Description
OEM Specific-Cache control.
Processor Status (1 FLAGS) Verification.
Test 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.
B-1
Appendix B: Post Codes