Parallel Protocol Request Message (I T); Wide Mode Setting Request From The Idd To The Init - Fujitsu MAN3184 SERIES Specifications

(b) Without ATTENTION condition
If the ATTENTION condition does not exist, the IDD does not send the WIDE DATA
TRANSFER REQUEST message to the INIT. In such case, the 8-bit bus width is set
between the IDD and the INIT.
Table 2.9
Message from TARG
Transfer Width
W
D
T
Exponent
R
= X'01'
2.3.21

PARALLEL PROTOCOL REQUEST message (I T)

Byte
X'01'
Bit 7
Byte7
QAS_REQ : Quick Arbitration Request
DT_REQ : Double Transfer Request
IU_REQ : Information Unit Request
The PARALLEL PROTOCOL REQUEST messages are used to negotiate a synchronous data
transfer agreement, a wide data transfer agreement, and set the protocol options between two SCSI
devices.
Note:
ST synchronous data transfer (Single Transfer)
DT synchronous data transfer (Double Transfer)
2 - 28

Wide mode setting request from the IDD to the INIT

Response message from IDD
MESSAGE REJECT
X'02' or larger
0 1 2
X'06' X'04'
m: Transfer Period Factor [4
n: REQ/ACK OFFSET
x: Transfer Width Exponent
x
Transfer width = 2 bytes
y: Protocol Options Bit
6 5 4
Reserved
C141-E123-01EN
X'00'
X'01'
3 4 5
m X'00' n
m (ns)]
3 2
QAS_REQ
Transfer width to be set
8-bit width
8-bit width
16-bit width
16-bit width
6 7
x y
1
DT_REQ IU_REQ
0