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| Chapter 4 Command Operation | |||||
Page 4 - 4 |
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| The Base Parameter Block | |||
The Base | The Parameter Block is one of the basic building blocks of the RF3880 | ||||||||||
Parameter | command structures. It is designed to hold all facts relevant to a single | ||||||||||
command. |
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Block |
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The same Parameter Block format is used whether the command is a Pass- | |||||||||||
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| through command directed to a SCSI device, or a | |||||||||
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| be interpreted and acted on by the adapter. (The various flags and byte values | |||||||||
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| may have different meanings in each case though.) |
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| All | |||||||||
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| information about how the RF3880 implements SCSI commands can be found | |||||||||
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| in Chapter 5. See a SCSI specification and | |||||||||
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| documentation for details about particular SCSI commands. |
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Parameter | The Parameter Block format for all | ||||||||||
Block Format | control commands is illustrated below: |
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| Address |
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| Byte Memory Address |
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| Offset |
| Offset + 0 | Offset + 1 |
| Offset + 2 | Offset + 3 |
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| 00H |
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| Command Identifier |
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| 04H |
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| Target/Adapter ID |
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| 08H |
| Command Options, Addresses, and Transfer Count |
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| 0CH |
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| 10H |
| Command Code |
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| 14H |
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| Command Descriptor Block |
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| 18H |
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| Table 17: Base Parameter Block |
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A brief description of each of the fields follows:
Command Identifier
When setting up a command structure, you use this field to distinguish a command in order to associate it with a returned Status Block. The value is a
21020285 D | User’s Guide |