Comments and Suggestions
   
Last updated: April 16, 1997


Memory Address Decoding

If a memory failure occurs during POST, and the Diag/Norm switch is in the Diag position, the U-number and the physical address of the failing SIMM are output to the serial port.

Use address Bits 28, 29, 30, and 31 of the physical address to isolate the board the failing SIMM is located on.

ADDRESS BITS BANK BOARD
0xxxxxxx 0 CPU
1xxxxxxx 1 CPU
2xxxxxxx 2 CPU
3xxxxxxx 3 CPU
4xxxxxxx 0 Memory 1
5xxxxxxx 1 Memory 1
6xxxxxxx 2 Memory 1
7xxxxxxx 3 Memory 1
8xxxxxxx 0 Memory 2
9xxxxxxx 1 Memory 2
axxxxxxx 2 Memory 2
bxxxxxxx 3 Memory 2

Use address Bits 0, 1, and 2 of the physical address to isolate the failing byte. Use address Bit 3 to determine if the failing SIMM is the Low or High SIMM within the bank.

ADDRESS BITS BYTE BITS LOW/HIGH SIMM
xxxxxxx7 0 0 - 7 Low
xxxxxxxf 0 0 - 7 High
xxxxxxx6 1 8 - 15 Low
xxxxxxxe 1 8 - 15 High
xxxxxxx5 2 16 - 24 Low
xxxxxxxd 2 16 - 24 High
xxxxxxx4 3 25 - 31 Low
xxxxxxxc 3 25 - 31 High
xxxxxxx3 4 32 - 39 Low
xxxxxxxb 4 32 - 39 High
xxxxxxx2 5 40 - 47 Low
xxxxxxxa 5 40 - 47 High
xxxxxxx1 6 48 - 55 Low
xxxxxxx9 6 48 - 55 High
xxxxxxx0 7 56 - 63 Low
xxxxxxx8 7 56 - 63 High


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