4-22
Registers
Full Arbitration, Selection/Reselection
1.
The LSI53C896 SCSI function waits for a bus free
condition.
2.
It asserts SBSY/ and its SCSI ID (the highest priority
ID stored in the
register) onto
the SCSI bus.
3.
If the SSEL/ signal is asserted by another SCSI
device or if the LSI53C896 SCSI function detects a
higher priority ID, the LSI53C896 SCSI function
deasserts SBSY, deasserts its ID, and waits until the
next bus free state to try arbitration again.
4.
The LSI53C896 SCSI function repeats arbitration
until it wins control of the SCSI bus. When it wins,
the Won Arbitration bit is set in the
register, bit 2.
5.
The LSI53C896 SCSI function performs selection by
asserting the following onto the SCSI bus: SSEL/,
the target’s ID (stored in the
register), and the LSI53C896’s ID (stored in
the
register).
6.
After a selection is complete, the Function Complete
bit is set in the
SCSI Interrupt Status Zero (SIST0)
register, bit 6.
7.
If a selection time-out occurs, the Selection
Time-Out bit is set in the
register, bit 2.
START
Start Sequence
5
When this bit is set, the LSI53C896 starts the arbitration
sequence indicated by the Arbitration Mode bits. The
Start Sequence bit is accessed directly in low level mode.
During SCSI SCRIPTS operations, this bit is controlled by
the SCRIPTS processor. Do not start an arbitration
sequence if the connected (CON) bit in the
register, bit 4, indicates that the
LSI53C896 is already connected to the SCSI bus. This bit
is automatically cleared when the arbitration sequence is
complete. If a sequence is aborted, check bit 4 in the
SCNTL1 register to verify that the LSI53C896 is not
connected to the SCSI bus.
Содержание LSI53C896
Страница 6: ...vi Preface...
Страница 16: ...xvi Contents...
Страница 88: ...2 62 Functional Description...
Страница 112: ...3 24 Signal Descriptions...
Страница 306: ...6 38 Specifications This page intentionally left blank...
Страница 310: ...6 42 Specifications This page intentionally left blank...
Страница 338: ...6 70 Specifications Figure 6 40 LSI53C896 329 BGA Bottom View...
Страница 340: ...6 72 Specifications...
Страница 346: ...A 6 Register Summary...
Страница 362: ...IX 12 Index...