Intel® 82854 Graphics Memory Controller Hub (GMCH)

4.10.3PCICMD – PCI Command Register

Address Offset:

04-05h

Default Value:

0006h

Access:

Read Only, Read/Write

Size:

16 bits

Since the Intel® 82854 GMCH Device #0 does not physically reside on PCI_A many of the bits are not implemented.

Bit

Descriptions

 

 

15:10

Reserved

 

 

9

Fast Back-to-Back Enable (FB2B): This bit controls whether or not the master can do fast back-

 

to-back Write. Since Device #0 is strictly a target, this bit is not implemented and is hardwired to

 

0. Writes to this bit position have no effect.

 

 

8

SERR Enable (SERRE): SERR# is not implemented by Function #1 of Device #0 of the GMCH

 

and this bit is hardwired to 0. Writes to this bit position have no effect.

 

 

7

Address/Data Stepping Enable (ADSTEP): Address/data stepping is not implemented in the

 

GMCH, and this bit is hardwired to 0. Writes to this bit position have no effect.

 

 

6

Parity Error Enable (PERRE): PERR# is not implemented by GMCH and this bit is hardwired to

 

0. Writes to this bit position have no effect.

 

 

5

VGA Palette Snoop Enable (VGASNOOP): The GMCH does not implement this bit and it is

 

hardwired to a 0. Writes to this bit position have no effect.

 

 

4

Memory Write and Invalidate Enable (MWIE): The GMCH will never issue Memory Write and

 

Invalidate commands. This bit is therefore hardwired to 0. Writes to this bit position will have no

 

effect.

 

 

3

Special Cycle Enable (SCE): The GMCH does not implement this bit and it is hardwired to a 0.

 

Writes to this bit position have no effect.

 

 

2

Bus Master Enable (BME): The GMCH is always enabled as a master on HI. This bit is

 

hardwired to a 1. Writes to this bit position have no effect.

 

 

1

Memory Access Enable (MAE): The GMCH always allows access to Main Memory. This bit is

 

not implemented and is hardwired to 1. Writes to this bit position have no effect.

 

 

0

I/O Access Enable (IOAE): This bit is not implemented in the GMCH and is hardwired to a 0.

 

Writes to this bit position have no effect.

 

 

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D15343-003

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Intel D15343-003 manual Pcicmd PCI Command Register