82845GL datasheet(80/193 Pages) INTEL

80 / 193 page

Intel® 82845G/82845GL/82845GV GMCH Datasheet

3.5.2.3

PCICMD1—PCI Command Register (Device 1)

Address Offset:

04–05h

Default Value:

0000h

Access:

RO, R/W

Size:

16 bits

Bit

Description

15:10

Reserved.

Fast Back-to-Back Enable (FB2B)—RO.

Hardwired to 0.

SERR Message Enable (SERRE).

This bit is a global enable bit for Device 1 SERR messaging. The

GMCH communicates the SERR# condition by sending an SERR message to the ICH. If this bit is

set to a 1, the GMCH is enabled to generate SERR messages over HI for specific Device 1 error

conditions that are individually enabled in the BCTRL1 register. The error status is reported in the

PCISTS1 register. If SERRE1 is reset to 0, then the SERR message is not generated by the GMCH

for Device 1.

Address/Data Stepping (ADSTEP).

Hardwired to 0. Address/data stepping is not implemented in

the GMCH.

Parity Error Enable (PERRE).

Hardwired to 0. Parity checking is not supported on the primary side

of this device.

Reserved.

Memory Write and Invalidate Enable (MWIE).

Hardwired to 0.

Special Cycle Enable (SCE).

Hardwired to 0.

Bus Master Enable (BME).

0 = Disable (Default). AGP Master initiated Frame# cycles are ignored by the GMCH. The result is a

master abort. Ignoring incoming cycles on the secondary side of the PCI-to-PCI bridge

effectively disabled the bus master on the primary side.

1 = AGP master initiated Frame# cycles are accepted by the GMCH if they hit a valid address

decode range. This bit has no affect on AGP Master originated SBA or PIPE# cycles.

Memory Access Enable (MAE).

0 = Disable. All of Device 1’s memory space is disabled.

1 = Enable. This bit must be set to 1 to enable the Memory and Pre-fetchable memory address

ranges defined in the MBASE1, MLIMIT1, PMBASE1, and PMLIMIT1 registers.

IO Access Enable (IOAE).

0 = Disable. All of Device 1’s I/O space is disabled.

1 = Enable. This bit must be set to1 to enable the I/O address range defined in the IOBASE1, and

IOLIMIT1 registers.

82845GL Datasheet(PDF) 80 Page - Intel Corporation

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