Parallel Protocol Request Message (I↔T); Table 2.9 Wide Mode Setting Request From The Hdd To The Init - Fujitsu MBA3073 SERIES Technical Manual

(b) Without ATTENTION condition
If the ATTENTION condition does not exist, the HDD does not send the WIDE DATA
TRANSFER REQUEST message to the INIT. In such case, the 8-bit bus width is set
between the HDD and the INIT.
Table 2.9
Message from TARG
Transfer Width
W
D
T
Exponent
R
= X'01'
2.3.22 PARALLEL PROTOCOL REQUEST message (I↔T)
Byte 0
X'01'
Bit 7 6
Byte7
PCMP_EN
PCMP_EN : Precompensation Enable
RTI : Retain Training Information
RD_STRM : Read Streaming
WR_FLOW : Write Flow Control
HOLD_MCS : Hold Margin Control Settings
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)
180
Wide mode setting request from the HDD to the INIT
Response message from HDD
MESSAGE REJECT
X'00'
X'01'
X'02' or larger
1 2 3
X'06' X'04' m
m: Transfer Period Factor [4 × m (ns)]
n: REQ/ACK OFFSET
x: Transfer Width Exponent
x
Transfer width = 2 bytes
y: Protocol Options Bit
5 4
RTI RD_STRM WR_FLOW HOLD_MCS
Transfer width to be set
16-bit width
16-bit width
4 5 6
X'00' n x
3 2
QAS_REQ
8-bit width
8-bit width
7
y
1 0
DT_REQ IU_REQ
C141-C015