Fujitsu 600C manual BUS FREE phase, 5 Signal delay times definition, Time

Table 4.5 Signal delay times definition

No.	Item	Time	definition
11	Hold time	45 ns	The minimum time added between the assertion of
			REQ (Or REQB) or ACK (or ACKB) and the
			changing of the data lines to provide hold time in the
			initiator or target while using synchronous data
			transfers. REQB and ACKIB timings only apply to
			optional wide data transfers.
12	Negation	90 ns	The minimum time that a target shall negate REQ (Or
			REQB) while using synchronous data transfers. Also,
			the minimum time that an initiator shall negate ACK
			(or ACKB) while using synchronous data transfers.
			REQB and ACKB timings only apply to optional
			wide data transfers.
13	Power-on to	10 sec	The recommended maximum time from power
	selection	(recommended)	application until an SCSI target is able to respond
	time		with appropriate status and sense data to the TEST
			UNIT READY, INQUIRY, and REQUEST SENSE
			commands
14	Reset to	250 ms	The recommended maximum time after a hard
	selection	(recommended)	RESET condition until an SCSI target is able to
	time		respond with appropriate status and sense data to the
			TEST UNIT READY, INQUIRY and REQUEST
			SENSE commands
15	Reset hold	25 æs	The minimum time over which RST must be kept
			asserted
16	Selection	200 æs	The maximum time required from the moment when
	abort time		selection or deselection of an initiator or target is
			detected until BSY is asserted
17	Selection	250 ms	The minimum time required for an initiator or target
	timeout	(recommended)	in the selection or deselection phase to wait for a
	delay		BSY response before it starts the timeout procedure
18	Transfer	⎯	The minimum allowable period, during sync data
	period		transfer, between the start of consecutive REQ pulses
			and the start of consecutive ACK pulses

4.3.1BUS FREE phase

The BUS FREE phase is used to indicate that no SCSI device is actively using the SCSI bus. and that it is available.

SCSI devices shall detect the BUS FREE phase after the SEL and BSY signals are both false for at least a bus settle delay.

SCSI devices shall release all SCSI bus signals within a bus clear delay after the BSY and SEL signals become continuously false for a bus settle delay.

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