6.Command Specification | READ BUFFER |
Echo Buffer (1010b) - In this mode the drive transfer data to the application client from the echo buffer. The echo buffer will transfer the same data as when the WRITE BUFFER command with the mode field set to echo buffer was issued. The BUFFER ID and BUFFER OFFSET fields are ignored in this mode. The READ BUFFER command will return the same number of bytes of data as received in the prior echo buffer mode WRITE BUFFER command from the same initiator.
The initiator may send a READ BUFFER command requesting the echo buffer descriptor prior to a WRITE BUFFER command. If an echo buffer mode WRITE BUFFER command is successful then the initiator may send multiple echo buffer mode READ BUFFER commands to read the echo buffer data multiple times.
Echo buffer descriptor (1011b) - In this mode, a maximum of four bytes of READ BUFFER descriptor information is returned. The drive will return the descriptor information for the echo buffer. The BUFFER OFFSET field is reserved in this mode. The allocation length will be set to four or greater.
Table 6-76: Echo Buffer descriptor
Bit | 7 | 6 | 5 |
| 4 |
| 3 | 2 | 1 | 0 | |
Byte |
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0 |
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| Reserved |
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| EBOS (1) | |
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1 |
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| Reserved |
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2 |
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| Reserved |
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| (MSB) |
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3 |
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| BUFFER CAPACITY |
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| (LSB) | |||
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The BUFFER CAPACITY field will return the size of the echo buffer in bytes aligned to a
SONY |
