Fujitsu MBC2073RC, MBC2036RC, MBA3300RC Command Format, Control byte, Handling an illegal CDB

2.1 Command Format

b.Transfer byte length or parameter list length

When the transfer data length is specified as the "Transfer Byte Length" or "Parameter List Length", this field specifies the length of the data transferred between the INIT and HDD by that command in number of bytes. When zero is specified in this field, data transfer is not executed, except in cases where it is particularly stipulated in the specifications for individual commands in Chapter 4.

In commands which send the parameters which are necessary for command execution are sent from the INIT to the HDD, this field is called "Parameter List Length" and specifies the total number of bytes of the parameter list sent by the INIT.

On the other hand, with commands which receive information from the HDD (REQUEST SENSE, INQUIRY, etc.), it is called "Transfer Byte Length" and specifies the maximum number of bytes that can be received from the INIT (the number of bytes in the area secured in the INIT for receiving information). The HDD transfers either the number of effective bytes of information specified by the command or the value specified in the "Transfer Byte Length", whichever value has the smaller number of bytes.

(4)Control byte

				Table 2.5		Control byte
Bit	7	6	5		4		3	2	1	0
0		0	0		0		0	0	0	0

a.Bits 7, 6 (vendor unique)

When any value other than "0" is specified for these bits, the HDD terminates command processing with the CHECK CONDITION status.

b.Bit 0 (Link)

This HDD does not support Link, so this bit should be set on "0".

(5) Handling an illegal CDB

If there are errors in the contents of a CDB description (specification), or if there is an error in the specification of a parameter transferred from the INIT in accordance with a CDB specification, that command ends with the CHECK CONDITION status. In the case of a command that changes data on the disk medium, when there is an error in the CDB specification, the disk medium is not changed by that command, but when there is an error in a parameter transferred in a DATA frame, the contents of the disk medium in the area specified in that command may be changed. Also, a DATA frame request may be executed after receiving a DATA frame, but those data are not used.

C141-C013 107