Fujitsu M2488 manual Data Transfer Disconnect Control

TAPE UNIT PARAMETERS						M2488 PRODUCT GUIDE
		Table 5-8.		Page 02 - Disconnect/Reconnect Parameters Field Description (Continued)
		BYTE	BIT	VALUE		DESCRIPTION
	8-9			0		The Connect Time Limit field indicates the maximum time, in 100 microsecond
						increments, that the target remains connected until it attempts to disconnect. A value
						of zero in this field indicates that there is no Connect Time Limit.
						The Connect Time Limit field is reported as not changeable on a MODE SENSE
						command, and the default value is zero.
	10-11					The Maximum Burst Size field indicates the maximum amount of data to be trans-
						ferred between SCSI bus disconnects when disconnects are allowed. The value in
						this field is multiplied by 512 bytes to signify the maximum amount of data. For
						example, a “1” in this field signifies 512 bytes and a “2” signifies 1024 bytes.
						A value of zero in this field indicates no limit on the amount of data transferred. The
						controller attempts to honor the specified value. However, in no case does the con-
						troller transfer only a portion of a record. When reading a compressed tape, the con-
						troller does not know how much uncompressed data is produced by a record about
						to be transferred. In this case, the compressed record length (rather than the actual
						bus transferred size) is used to determine if the maximum burst size is exceeded.
						The Maximum Burst Size field is reported as not changeable on a MODE SENSE
						command, and the default value is zero.
	12		0-1			The Data Transfer Disconnect Control (DTDC) field defines further restrictions on
						when a disconnect is permitted. Table 5-9 relates the significance of different values
						in this field.
					Table 5-9. Data Transfer Disconnect Control
		DTDC				DESCRIPTION
		00b	Data transfer disconnect control is not used. Disconnect is controlled by the other fields in this page.
			A target will not disconnect once the data transfer of a command has started until all data the command
		01b	is to transfer has been transferred. The connect time limit and bus inactivity limit are ignored during the
			data transfer.
		10b	Reserved
		11b	A target will not disconnect once the data transfer of a command has started until the command is com-
			plete. The connect time limit and bus inactivity limit are ignored once data transfer has started.

If the DTDC field is non-zero and the Maximum Burst Size is non-zero, the target shall return CHECK CONDITION status. The sense key will be set to ILLEGAL REQUEST and the additional sense code set to ILLEGAL FIELD IN PARAMETER LIST.

The DTDC field is reported as changeable on a MODE SENSE command, and the default value is zero.

5-8 CG00000-011503 REV. A April 1997