Chapter 7 Board-control Commands
Extended Unit Options (18H) | Page 7 - 45 |
Extended Unit Options (18H)
Command
Format
This command, in either initiator or target mode, is designed as an enhancement to the Unit Options command. The primary difference between the commands is the opportunity to select 16 bytes of Sense Data to be returned per unit, instead of the eight offered in the Unit Options command.
Another difference is that the Extended Unit Options for the SCSI device are built into a Data Structure whose address is simply passed in the command.
The format of the Extended Unit Options command is as follows:
Address |
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| Byte Memory Address |
| ||
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 | Reserved |
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| Addr. Mod. | Adapter ID = FFH | |
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08H |
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| VME Memory Address |
| ||
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0CH |
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| Reserved |
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10H | Command = 18H |
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| Reserved |
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14H |
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| Reserved |
| |
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18H |
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| Reserved |
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Description of Fields
Table 103: Extended Unit Options Parameter Block
Each of the fields of the Parameter Block are described below:
Command Identifier
The Command Identifier field is used to identify the Status Block associated with a Parameter Block. It must be a unique value.
Adapter ID
This is a
Address Modifier
This is the value to be used by the adapter on the Address Modifier lines when reading the Extended Unit Options Data Structure from memory.
VME Memory Address
This is the system memory address at which you have built the Extended Unit Options Data Structure.
Command Code
The value for this field will always be 18H to indicate a Extended Unit Options command.
The format of the Data Structure to be used for the Extended Unit Options command is illustrated on the following pages.
User’s Guide | 21020285 D |