HP XU700 page, page, SMBus Controller, ICH2 Architecture, ICH2 PCI Bus Interface, Low Pin Count Interface, Enhanced USB Controller

2 System Board

The Input/Output Controller Hub 2 (82801BA)

ICH2 Architecture The ICH2 interface architecture ensures that the I/O subsystems, both PCI and the integrated input/output features (for example: IDE, AC’97 and USB) receive the adequate bandwidths.

To achieve this, by placing the I/O bridge directly on the ICH2 interface, and no longer on the PCI bus, the ICH2 architecture ensures that both the input/output functions integrated into the ICH2 and the PCI peripherals obtain the bandwidth necessary for peak performance.

ICH2 PCI Bus Interface The ICH2 PCI provides the interface to a PCI bus interface operating at 33 MHz. This interface implementation is compliant with PCI Rev 2.2 Specification, supporting up to five external PCI masters in addition to the ICH2 requests. The PCI bus can reach a data transfer rate of 133 MBytes/sec. The maximum PCI burst transfer can be between 256 bytes and 4 KB. It also supports advanced snooping for PCI master bursting, and provides a pre-fetch mechanism dedicated for IDE read.

Refer to the table page 59 for ICH2 interrupts.

SMBus Controller The System Management (SM) bus is a two-wire serial bus which runs at a maximum of (100 kHz). The SMBus Host interface allows the processor to communicate with SMBus slaves and an SMBus Slave interface that allows external masters to activate power management events. The bus connects to sensor devices that monitor some of the hardware functions of the system board, both during system boot and run-time.

Refer to page 47 for a description of the devices on the SMBus, or to page 50 for information on the MaxiLife ASIC.

Low Pin Count Interface The ICH2 implements the LPC interface 1.0 specification.

Enhanced USB Controller The USB (Universal Serial Bus) controller provides enhanced support for the Universal Host Controller Interface (UHCI). This includes support that allows legacy software to use a USB-based keyboard and mouse. The USB supports four stacked connectors on the back panel. These ports are built into the ICH2, as standard USB ports.

The ICH2 is USB revision 1.1 compliant.

USB works only if the USB interface has been enabled within the HP Setup program. Currently, only the Microsoft Windows 95 SR2.1, Windows 98 and Windows 2000 operating systems provide support for the USB.