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nVIDIA MCP73 Series Users Manual
APPENDIX 1
POST Codes
NOTE: EISA POST codes are typically output to port address 300h.
ISA POST codes are output to port address 80h.
Code
(hex) Name Description
C0 Turn Off Chipset Cache
OEM Specic-Cache control
1 Processor Test 1 Processor Status (1FLAGS) Verication. Tests the following
processor status ags: carry, zero, sign, overow, The BIOS
sets each ag, veries they are set, then turns each ag off
and veries it is off.
2 Processor Test 2 Read/Write/Verify all CPU registers except SS, SP, and BP with
data pattern FF and 00.
3 Initialize Chips 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.
4 Test Memory Refresh RAM must be periodically refreshed to keep the memory from
Toggle
decaying. This function ensures that the memory refresh
function is working properly.
5 Blank video, Initialize Keyboard controller initialization.
keyboard
6 Reserved
7 Test CMOS Interface and Veries CMOS is working correctly, detects bad battery.
Battery Status
BE Chipset Default Program chipset registers with power on BIOS defaults.
Initialization
C1 Memory presence test OEM Specic-Test to size on-board memory.
C5 Early Shadow OEM Specic-Early Shadow enable for fast boot.
C6 Cache presence test
External cache size detection.
8 Setup low memory
Early chip set initialization. Memory presence test OEM chip
set routines. Clear low 64K of memory. Test rst 64K memory.