SCSI Functional Description
2-51
If the implementation shown in
is used, INTC/ and INTD/ of
the PCI RAID upgrade slot cannot be used when a non-RAID upgrade
card is installed in the slot. If this restriction is not acceptable, additional
buffer logic must be implemented on the mainboard. As long as the
interrupt routing requirements stated above are satisfied, a mainboard
designer could implement this design with external logic.
Figure 2.8
Interrupt Routing Hardware Using the LSI53C896
There can only be one entity controlling a mainboard SCSI core or
conflicts will occur. Typically a SCSI core will be controlled by the SCSI
BIOS and an operating system driver. When a SCSI core is allocated to
a RAID adapter, however, a mechanism must be implemented to prevent
the SCSI BIOS and operating system driver from trying to access the
SCSI core. The mainboard designer has several options to choose from
for doing this.
The first option is to have the SCSI core load its PCI Subsystem ID using
a serial EPROM on power-up. If bit 15 in this ID is set, the LSI Logic
BIOS and operating system drivers will ignore the chip. This makes it
possible to control the assignment of the mainboard SCSI cores using a
configuration utility.
A4
A6
A7
B8
B7
SCSI Core
I
SCSI Core
II
LSI53C896
ALT_INTA/
2.7 K
+ 5 V
INTA/
ALT_INTB/
INTB/
2.7 K
+ 5 V
INTB/
INTD/
INTA/
INTC/
TDI
+ 5 V
INT_DIR
PCI RAID
Upgrade
Slot INTA/
PCI RAID
Upgrade
Slot INTB/
MB SCSI INTA/
MB SCSI INTB/
These interrupt lines are
connected to the other PCI
slot interrupt lines as
determined by the
mainboard interrupt
routing scheme.
10 K
PCI RAID UPGRADE SLOT
*
Summary of Contents for LSI53C896
Page 6: ...vi Preface...
Page 16: ...xvi Contents...
Page 88: ...2 62 Functional Description...
Page 112: ...3 24 Signal Descriptions...
Page 306: ...6 38 Specifications This page intentionally left blank...
Page 310: ...6 42 Specifications This page intentionally left blank...
Page 338: ...6 70 Specifications Figure 6 40 LSI53C896 329 BGA Bottom View...
Page 340: ...6 72 Specifications...
Page 346: ...A 6 Register Summary...
Page 362: ...IX 12 Index...