Write Buffer

2.44Write Buffer (3Bh)

Operation Code is (3Bh).

Mode specifies meaning of the Buffer Offset field.

Buffer ID is not supported. This byte must be 00h.

Buffer Offset is the byte offset in the buffer where the data shall be stored. This must be 0

through 15.

Transfer Length is the number of bytes to be transferred in the DATA OUT phase. This must be the data length to be sent plus 4 bytes (header size).

This command is to be used with the READ BUFFER command to test the reliability of the command buffer memory in the drive, and of the SCSI bus. The drive does not access any discs.

Mode

Definition

00b

Header, data, and buffer offset are 0s.

01b

Buffer offset indicates the offset of the buffer at which data are to be stored.

10b

Reserved

11b

Reserved

The transfer length must include the 4-byte header, therefore, the actual data length to be stored is the transfer length minus 4 bytes. As the buffer length of the drive is 16 bytes, the maximum number of bytes that can be specified for Buffer Offset is 15, and the maximum for Transfer Length is 20.

If Transfer length is larger than 20, a Check Condition is returned with the sense key "ILLEGAL REQUEST." Check Condition will also be returned if the Buffer Offset + Transfer Length is larger than 20.

If Buffer Offset is not 0 when Mode is 00h, Check Condition is returned.

Refer to Table 2-38A on the opposite page for the 4-byte header of 00h's must be sent preceding the test data.

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