A |
COMMON COMMAND SET AND DISK OPERATION
| BYTE | VALUE | COMMENTS | |
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1 | 01 | Extended message | ||
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2 | 03 | Extended message length | ||
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3 | 01 | Synchronous data transfer | ||
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| request | |
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4 | 32 | Transfer period (50 times 4 ns | ||
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| = 200 ns | |
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5 | 05 | REQ/ACK offset | ||
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| Test Unit Ready Command CDB |
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| BYTE OFFSET | VALUE | COMMENTS | |
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0 | 00 | Command code | ||
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1 | 00 | LUN is inserted into bits | ||
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2 | 00 | Reserved | ||
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3 | 00 | Reserved | ||
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4 | 00 | Reserved | ||
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5 | 00 | Control byte: no link, no flag | ||
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The firmware sends a mode sense command for page 3, current values. The returned block size is compared to the block size in the packet; if they are not the same, the firmware sets a internal flag to block all subsequent read or write commands. In this case, the firmware returns a command error ($0B) status.
Mode Sense Command CDB
| BYTE OFFSET | VALUE | COMMENTS | |
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0 | 1A | Command code | ||
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1 | 00 | LUN is inserted into bits | ||
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2 | 03 | Page 3, current values | ||
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3 | 00 | Reserved | ||
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4 | 2C | Allocation length | ||
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5 | 00 | Control byte: no link, no flag | ||
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The READ/WRITE command performs the following to a Winchester disk:
