Fujitsu M2488 manual PC Field Description Bits

MEDIA CHANGER COMMANDS						M2488 PRODUCT GUIDE
				Table 6-9.		MODE SENSE Field Description (Continued)
	BYTE		BIT	VALUE		DESCRIPTION
	2		6-7		The Page Control (PC) field indicates the type of page parameter values to be
					returned by the target. The target returns the same page length for each supported
					page regardless of the value in the PC. The combination of the page control field
					value and the page code being set causes the target to return the appropriate values
					for the page selected by its respective page code. A Page Code value of 3Fh indi-
					cates all pages implemented by the target are returned to the initiator with the values
					reported defined by the page control field. For a Page Code value of 3Fh, all pages
					are returned in ascending page code order, except for mode page 00h, which will
					always be reported last. The PC field is defined in Table 6-10.
					Regardless of the setting of the PC field, the Mode Sense data header will return the
					current values for the fields contained in it, since the SP (Save Pages) bit only
					applies to the Mode Pages, and not the header.
	4				The Allocation Length specifies the number of bytes the initiator has allocated for
					returned MODE SENSE data. An Allocation Length of zero indicates no MODE
					SENSE data is to be transferred. This condition is not considered as an error. Any
					other value indicates the maximum number of bytes transferred. The target termi-
					nates the DATA IN phase when allocation length bytes have been transferred or
					when all available MODE SENSE data has been transferred to the initiator, which-
					ever is less.
						Table 6-10. PC Field
	PC FIELD					DESCRIPTION
	BITS
7		6
			Report Current Values: The current values are those parameters under which the target is presently config-
			ured. The current values are defined to be the following:
			1. those values set in the last successfully completed MODE SELECT command
0		0	2. saved values if a MODE SELECT hasn’t successfully completed since the last power-on, hard reset
			condition or BUS DEVICE RESET message,
			3. default values if saved values are not available.
			Page fields not supported are set to zero. The additional page length field returned by the target indicates
			the number of bytes supported in that page.

Report Changeable Values: The changeable values of any page indicate which parameters the initiator may change by a subsequent MODE SELECT command. Any field allowed to change is set to all ones. Fields and bits not allowed to be changed by the initiator are set to zero. Attempting to change any field,

01 via MODE SELECT command, that is not changeable causes the target to return a CHECK CONDITION status with the sense key set to ILLEGAL REQUEST in the sense data. The additional page length field of each page returned by the target indicates the number of bytes which are supported for that particular page.

Report Default Values: The target returns to the initiator the field values set to the target’s or device’s

10 default values. The additional pages length field of each page returned by the target indicates the number of bytes supported for that particular page.

Report Saved Values: The target returns the saved values of the mode parameters. Until the first success-

11 ful MODE SELECT command is completed with the SP (Save Pages) bit set to 1, the default values will be returned for this PC field setting.

6-12 CG00000-011503 REV. A March 1997