Motorola MVME5100 Manual Do Utilizador
Vital Product Data (VPD) Introduction
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B-15
B
Serial Presence Detect (SPD) Checksum Calculation
The checksum field (Byte 63) designates the checksum for checking data
integrity (similar to parity) for bytes 0-62. It is written during board
production and can be used to verify the data integrity for these bytes.
integrity (similar to parity) for bytes 0-62. It is written during board
production and can be used to verify the data integrity for these bytes.
The process for calculating the Checksum includes the following:
1. Convert the binary information in byte locations 0-62 to decimal.
2. Add together (sum) all decimal values for addresses 0-62.
3. Divide the sum by 256.
4. Convert the remainder to binary (will be less than 256).
5. Store the result (single byte) in address 63 as “Checksum.”
Note
The same result can be obtained by adding the binary values in
addresses 0-62 and eliminating all but the low order byte. The
low order byte is the “Checksum.”
addresses 0-62 and eliminating all but the low order byte. The
low order byte is the “Checksum.”