The signal delay times for each bus phase are defined as follows-

Table 4-5Signal delay times definition

No.

Item

Time

Definition

 

 

 

 

 

 

 

 

1

Arbitration

2.4 æs

The minimum time an SCSI device shall wait from

 

delay

 

asserting BSY for arbitration until the DATA BUS can

 

 

 

be examined to see if arbitration has been won. There is

 

 

 

no maximum time.

2

Assertion

90 ns

The minimum time that a target shall assert REQ (or

 

period

 

REQB) while using synchronous data transfers. Also,

 

 

 

the minimum time that an initiator shall assert ACK

 

 

 

while using synchronous data transfers.

3

Bus Clear

800 ns

The maximum time for an SCSI device to stop driving

 

delay

 

all bus signals after: (1) The BUS FREE phase is

 

 

 

detected (BSY and SEL both false for a bus settle delay)

 

 

 

(2) SEL is received from another SCS] device during the

 

 

 

ARBITRATION phase (3) The transition of RST to true.

 

 

 

For the first condition listed. the maximum time for an

 

 

 

SCSI device to clear the bus is 1200 nanoseconds from

 

 

 

BSY and SEL first becoming both false. If an SCSI

 

 

 

device requires more than a bus settle delay to detect

 

 

 

BUS FREE phase, it shall clear the bus within a bus

 

 

 

clear delay minus the excess time

4

Bus free delay

800 ns

The minimum time that an SCSI device shall wait from

 

 

 

its detection of the BUS FREE phase (BSY and SEL

 

 

 

both false

5

Bus set delay

1.8 _s

The maximum time for an SCSI device to assert BSY

 

 

 

and its SCSI ID bit on the DATA BUS after it detects

 

 

 

BUS FREE phase (BSY and SEL both false for a bus

 

 

 

settle delay) for the purpose of entering the

 

 

 

ARBITRATION phase

6

Bus settle

400 ns

The minimum time to wait for the bus to settle after

 

delay

 

changing certain control signals as called out in the

 

 

 

protocol definitions

7

Cable skew

10 ns

The maximum difference in propagation time allowed

 

delay

 

between any two SCSI bus signals measured between

 

 

 

any two SCSI devices.

8

Data release

400 ns

The maximum time for an initiator to release the DATA

 

delay

 

BUS signals following the transition of the I/O signal

 

 

 

from false to true.

9

Deskew delay

45 ns

The minimum time required for deskew of certain

 

 

 

signals

10

Disconnection

200 æs

The minimum time that a target shall wait after

 

 

 

releasing BSY before participating in an

 

 

 

ARBITRATION phase when honoring a DISCONNECT

 

 

 

message from the initiator

4-10

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Fujitsu 600C manual 5Signal delay times definition Time Definition