User's Manual

Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

Term Description

MCH The Memory Controller Hub component that contains the processor interface,

DRAM controller, and AGP interface. The MCH communicates with the ICH over

a proprietary interconnect called the hub interface (previously known as

HubLink). The MCH was called the North Bridge (NB) in previous chip sets.

MCH will be used to refer to non-graphics portion of the GMCH.

MM Memory Mapped address space.

MMIO Memory Mapped I/O space.

QW Quad Word = 64 bits = 8 Bytes.

R/W (register) Read/Write. A register with this attribute can be read and written.

R/WC (register) Read/Write Clear. A register bit with this attribute can be read and written.

However, a write of 1 clears (sets to 0) the corresponding bit and a write of 0 has

no effect.

R/WO (register) Read/Write Once. A register bit with this attribute can be written to only once

after power up. After the first write, the bit becomes read only.

RO (register) Read Only. In some cases, if a register is read only, writes to this register

location have no effect. However, in other cases, two separate registers are

located at the same location where a read accesses one of the registers and a

write accesses the other register. See the I/O and memory map tables for

details.

WO (register) Write Only. In some cases, If a register is write only, reads to this register

location have no effect. However, in other cases, two separate registers are

located at the same location where a read accesses one of the registers and a

write accesses the other register. See the I/O and memory map tables for

details.

1.2. Reference Documents

The following documents should be available for reference when using this specification:

• Intel

815 Chipset: Intel

82815 chipset Graphics and Memory Controller Hub (GMCH) External

Design Specification (EDS)

• Intel

82801AA (ICH) and Intel

82801AB (ICH0) I/O Controller Hub Datasheet

• Intel

82801BA (ICH2) I/O Controller Hub External Design Specification (EDS)

• Intel

82802AB/82802AC Firmware* Hub (FWH) Datasheet