82801BA Datasheet, PDF (32/498 Pages) Intel Corporation – Intel 82801BA I/O Controller Hub 2 (ICH2) and Intel 82801BAM I/O Controller Hub 2 Mobile

Introduction
The following sub-sections provide an overview of the ICH2 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/100, coupled with the existing USB, I/O
requirements could impact PCI bus performance. The 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 ICH2 and the PCI
peripherals obtain the bandwidth necessary for peak performance.
PCI Interface
The ICH2 PCI interface provides a 33 MHz, Rev. 2.2 compliant implementation. All PCI signals
are 5V tolerant, except PME#. The ICH2 integrates a PCI arbiter that supports up to six external
PCI bus masters in addition to the internal ICH2 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 100 Mbytes/sec. It does not
consume any ISA DMA resources. The IDE interface integrates 16x32-bit buffers for optimal
transfers.
The ICH2’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 5.15,
“IDE Controller (D31:F1)” on page 5-99 for details).
Low Pin Count (LPC) Interface
The ICH2 implements an LPC Interface as described in the LPC 1.0 specification. The Low Pin
Count (LPC) Bridge function of the ICH2 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 current 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.
1-4
82801BA ICH2 and 82801BAM ICH2-M Datasheet