HP Vectra VL800, Technical Reference Manual

Page: 60 / 147

60
3 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 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 75 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 62 for a description of the devices on the SMBus, or to page 65
for information on the hardware monitoring 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 two 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 USB.