4-74
Registers
SCRIPTS Step interrupt, read the
and
registers to recognize
and clear the interrupt. Then set the START DMA bit in
this register.
IRQM
IRQ Mode
3
When set, this bit enables a totem pole driver for the
INTA/, or INTB/ pin. When cleared, this bit enables an
open drain driver for the INTA/, or INTB/, pin with an
internal weak pull-up. The bit should remain cleared to
retain full PCI compliance.
STD
Start DMA Operation
2
The LSI53C896 SCSI function fetches a SCSI SCRIPTS
instruction from the address contained in the
register when this bit is set. This
bit is required if the LSI53C896 SCSI function is in one
of the following modes:
•
Manual start mode – Bit 0 in the
register is set
•
Single step mode – Bit 4 in the
register is set
When the LSI53C896 SCSI function is executing
SCRIPTS in manual start mode, the Start DMA bit must
be set to start instruction fetches, but need not be set
again until an interrupt occurs. When the LSI53C896
SCSI function is in single step mode, set the Start DMA
bit to restart execution of SCRIPTS after a single step
interrupt.
IRQD
INTA, INTB Disable
1
Setting this bit disables the INTA (for SCSI Function A),
or INTB (for SCSI Function B) pin. Clearing the bit
enables normal operation. As with any other register
other than
Interrupt Status Zero (ISTAT0)
,
this register cannot be accessed except by a
SCRIPTS instruction during SCRIPTS execution. For
more information on the use of this bit in interrupt
handling, see
Chapter 2, “Functional Description.”
COM
LSI53C700 Family Compatibility
0
When the COM bit is cleared, the LSI53C896 SCSI
function behaves in a manner compatible with the
*
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...