SB82371 Intel Corporation, SB82371 Datasheet - Page 95

• Manufacturer Part Number: SB82371
• Description: 82371FB (PIIX) AND 82371SB (PIIX3) PCI ISA IDE XCELERATOR
• Manufacturer: Intel Corporation

3.5.
The PIIX/PIIX3 integrates a high performance interface from PCI to IDE. This interface is capable of
accelerated PIO data transfers as well as acting as a PCI Bus master on behalf of an IDE DMA slave device.
The PIIX/PIIX3 provides an interface for both primary and secondary IDE connectors (Figure 3).
The IDE data transfer command strobes, DMA request and grant signals, and IORDY signal interface directly
to the PIIX. The IDE data lines interface directly to the PIIX, and are buffered to provide part of the ISA
address bus as well as the X-Bus chip select signals. The IDE address and chip select signals are
multiplexed onto the LA[23:17] lines. The IDE connector signals are driven from the LA[23:17] lines by an
ALS244 buffer.
Only PCI masters have access to the IDE port. ISA Bus masters cannot access the IDE I/O port addresses.
Memory targeted by the IDE interface acting as a PCI Bus master on behalf of IDE DMA slaves must reside
on PCI, usually main memory implemented by the host-to-PCI bridge.
NOTES:
Support for Older Drives: There are cases where the PIIX/PIIX3 asserts both IDE chip selects (CS1x and CS3x). Some older
drives may not operate properly when both chip selects are asserted. Because the IDE chip selects are muxed with the ISA LA
lines, the 74ALS00 in the figure is used to ensure proper operation of older drives by gating the LA signals with SOE#.
PIIX/PIIX3
ISA Bus Signals
LA[23:17]
PCI Local Bus IDE
SOE#
SDIR
SOE#
SDIR
ALS245
SA[19:8]
SBHE#
PCS#
APICCS#
DD[15:0]
ALS245
Figure 3. PIIX/PIIX3 IDE Interface
DA[2:0]
CS1S
CS3S
CS1P
CS3P
DA[2:0]
LA[23]/
LA[22]/
LA[21]/
LA[20]/
SOE#
74ALS00
CS1S#
CS1P#
CS3P#
CS3S#
051903
IORDY
82371FB (PIIX) AND 82371SB (PIIX3)
DIOW#
DIOR#
DDRQ0
DDACK0#
DDRQ1
DDACK1#
Connector
Primary
Secondary
Connector
051903_3.drw
IDE
IDE
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