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ISA PORT codes are typically output to port address 80h.
Post
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
Name
OEM Specific-Cache controller.
Processor Status (1 FLAGS) Verification.
Tests the following processor status flags carry, zero,
sign, overflow.
The BIOS will set each of these flags, verify the 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 OO.
Disable NMI, PIE, AIE, UEI, SOWV.
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 inorder 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.
Description
40
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