Seagate Ultra 160, Руководство по эксплуатации продукта

Страница: 93 / 186

Parallel SCSI Interface Product Manual, Rev. A 79
The final information transfer phase is normally the MESSAGE IN phase where a DISCONNECT or TASK
COMPLETE message is transferred, followed by the BUS FREE phase.
Figure 11. Phase sequences for physical reconnection and selection using attention condition with information
unit transfers disabled
3.11.3 Phase sequences for selection without using attention condition with information unit
transfers disabled
The allowable sequences for either physical reconnection or selection using attention condition while an infor-
mation unit transfer agreement is not in effect shall be as shown in Figure
12.
The normal progression for selection without using attention condition (see Section 3.2.1.1.2) is:
1. from the BUS FREE phase to ARBITRATION;
2. from ARBITRATION to SELECTION;
3. from SELECTION to COMMAND phase;
4. from COMMAND phase to DATA phase;
5. from DATA phase to STATUS phase;
6. from STATUS phase to MESSAGE IN phase where a TASK COMPLETE message is transferred; and
7. from MESSAGE IN to BUS FREE phase.
Figure 12. Phase sequences for selection without using attention condition with information unit transfers
disabled
MESSAGE OUT
COMMAND
DATA
STATUS
SELECTION
ARBITRATION BUS FREE
Hard reset
or protocol
error
RESELECTION
MESSAGE IN
COMMAND
(note)
DATA
STATUS
MESSAGE IN
SELECTION
ARBITRATION BUS FREE
Hard reset
or protocol
error
MESSAGE OUT