IBM IC35L036UWDY10 Hard Drive Specifications - Page 66

8.1 SCSI Control Byte The Control Byte is the last byte of every CDB. The format of this byte is shown below. 7 6 VU = 0 Bit 5 4 3 2 1 0 Reserved = 0 FLAG LINK Figure 49. SCSI Control Byte VU FLAG LINK VU stands for Vendor Unique. The Flag bit specifies which message the drive shall return to the initiator if the link bit is one and the command completes without any error. If Link is zero, Flag must also be zero. If Link is one and the command terminates successfully, the drive will send either the LINKED COMMAND COMPLETE message (FLAG=0) or the LINKED COMMAND COMPLETE WITH FLAG message (FLAG=1). Typically this bit is used to cause an interrupt in the initiator between linked commands. This bit is set to one to indicate that the initiator desires an automatic link to the next command upon successful completion of the current command. Upon successful completion of the command, the drive will return INTERMEDIATE GOOD status and then send one of the two messages defined under Flag above. Upon unsuccessful completion of the command, the drive will return CHECK CONDITION status or RESERVATION CONFLICT status and then send the COMMAND COMPLETE message. No further commands in the chain are executed. 8.2 Abbreviations These abbreviations are used throughout the following sections: CDB Command descriptor block LBA Logical Block Address LSB Least significant bit LUN Logical Unit Number. An encoded three-bit identifier for the logical unit MSB Most significant bit RSVD Reserved VU Vendor unique bits 8.3 Byte ordering conventions In this specification, where it is not explicitly stated, all multibyte values are stored with the most significant byte first. For example, in a 4-byte field byte 0 will contain the MSB and byte 3 the LSB. Ultrastar 146Z10 hard disk drive specifications 50