Target Maximum
Initiator's Transfer Burst
Response Period Rate
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ ÄÄÄÄÄÄÄÄÄÄ ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
0 <= Mi <= 11 Send Message Reject(Async mode) N/A
12 <= Mi <= 12 50 nSec 20.00 MT/s
13 <= Mi <= 18 75 nSec 13.33 MT/s
19 <= Mi <= 25 100 nSec 10.00 MT/s
26 <= Mi <= 31 125 nSec 8.00 MT/s
32 <= Mi <= 37 150 nSec 6.67 MT/s
38 <= Mi <= 43 175 nSec 5.71 MT/s
44 <= Mi <= 50 200 nSec 5.00 MT/s
51 <= Mi <= 56 225 nSec 4.44 MT/s
57 <= Mi <= 62 250 nSec 4.00 MT/s
63 <= Mi <= 68 275 nSec 3.64 MT/s
69 <= Mi <= 75 300 nSec 3.33 MT/s
76 <= Mi <= 81 325 nSec 3.08 MT/s
82 <= Mi <= 87 350 nSec 2.86 MT/s
88 <= Mi <= 93 375 nSec 2.67 MT/s
94 <= Mi <= 100 400 nSec 2.50 MT/s
101 <= Mi <= 106 425 nSec 2.35 MT/s
107 <= Mi <= 255 Send Message Reject(Async mode) N/A
Figure 130. Target Response to Initiator's Transfer Period(F-20 mode)
9.1.3 WIDE DATA TRANSFER REQUEST (01,02,03H)
A pair of Wide Data Transfer Request messages are exchanged between an Initiator and a Target to establish
a data transfer width agreement between the two devices. The Initiator may initiate a wide data transfer
negotiation at any time after the LUN has been identified. The Target initiates a wide data transfer negoti-
ation if the Target has not negotiated with the Initiator since the last time the Target was Reset (Power-on
Reset, SCSI Bus Hard Reset, or Bus Device Reset message).
Target-initiated negotiation occurs either immediately following the Command phase or immediately fol-
lowing the first reconnection. In either case, negotiation occurs before any Data phase between the Target
and the Initiator. The Target will negotiate the data transfer width agreement prior to negotiating the syn-
chronous data transfer agreement. If a synchronous data transfer agreement is in effect when a Wide Data
Transfer Request message is received, the Target will reset the synchronous agreement to asynchronous
mode.
The implied data transfer width agreement remains in effect until the Target is Reset (Power-on Reset, SCSI
Bus "hard" Reset, or Bus Device Reset message) or a new data transfer width agreement is negotiated. If a
Reset occurs, the Target goes to eight bit mode.
Byte Value Description
ÄÄÄÄ ÄÄÄÄÄ ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
0 01H Extended message
1 02H Extended message length
2 03H Wide Data Transfer Request code
3 E Transfer Width Exponent
Figure 131. Wide Data Transfer Request.
SCSI MESSAGE SYSTEM
167
To Next Page
Loading...
