
Introduction
1-4
82801AA and 82801AB Datasheet
The following sub-sections provide an overview of I/O Controller Hub capabilities.
Hub Architecture
As I/O speeds increase, the demand placed on the PCI bus by the I/O bridge has become
significant. With the addition of AC’97 and Ultra ATA/66, coupled with the existing USB, I/O
requirements could impact PCI bus performance. The Intel
810 chipset’s
hub interface
architecture
ensures that the I/O subsystem; both PCI and the integrated I/O features (IDE, AC’97,
USB, etc.), will receive adequate bandwidth. By placing the I/O bridge on the hub interface
(instead of PCI), the hub architecture ensures that both the I/O functions integrated into the ICH
and the PCI peripherals obtain the bandwidth necessary for peak performance.
PCI Interface
The ICH PCI interface provides a 33 MHz, Rev. 2.2 compliant implementation. All PCI signals are
5V tolerant, except PME#. The ICH integrates a PCI arbiter that supports up to four
(ICH0: 82801AB) or six (ICH: 82801AA) external PCI bus masters in addition to the internal ICH
requests.
IDE Interface (Bus Master capability and synchronous DMA Mode)
The fast IDE interface supports up to four IDE devices providing an interface for IDE hard disks
and CD ROMs.
Each IDE device can have independent timings.
The IDE interface supports PIO
IDE transfers up to 14 Mbytes/sec and Bus Master IDE transfers up to 33 Mbytes/sec for the ICH0
(82801AB) and 66 Mbytes/sec for the ICH (82801AA). It does not consume any ISA DMA
resources.
The IDE interface integrates 16x32-bit buffers for optimal transfers.
The ICH’s IDE system contains two independent IDE signal channels.
They can be electrically
isolated independently. They can be configured to the standard primary and secondary channels
(four devices). There are integrated series resistors on the data and control lines (see
Section 5.14,
“IDE Controller (D31:F1)” on page 5-66
for details).
Low Pin Count (LPC) Interface
The ICH implements an LPC Interface as described in the LPC 1.0 specification. The Low Pin
Count (LPC) Bridge function of the ICH resides in PCI Device 31:Function 0. In addition to the
LPC bridge interface function, D31:F0 contains other functional units including DMA, Interrupt
Controllers, Timers, Power Management, System Management, GPIO, and RTC.
Note that in the Intel
810 chipset platform, the Super I/O (SIO) component has migrated to the
Low Pin Count (LPC) interface. Migration to the LPC interface allows for lower cost Super I/O
designs.