GXM Datasheet, PDF (158/244 Pages) National Semiconductor (TI) – Geode™ GXm Processor Integrated x86 Solution with MMX Support

Integrated Functions (Continued)
Bit
Name
Index 00h-01h
31:0
VID (RO)
Index 02h-03h
31:0
DIR (RO)
Index 04h-05h
15:10
9
RSVD
FBE
8
SERR
7
WAT
6
PE
5
VPS
4
MS
3
SPC
2
BM
1
MS
0
IOS
Index 06h-07h
15
DPE
14
SSE
13
RMA
12
RTA
11
STA
10:9
DT
Table 4-40. PCI Configuration Registers
Description
Vendor Identification Register (RO)
Default Value = 1078h
Vendor Identification Register (Read Only): The combination of this value and the device ID uniquely
identifies any PCI device. The Vendor ID is the ID given to national Semiconductor Corporation by the
PCI SIG.
Device Identification Register (RO)
Default Value = 0001h
Device Identification Register (Read Only): This value along with the vendor ID uniquely identifies any
PCI device.
PCI Command Register (R/W)
Default Value = 0007h
Reserved: Set to 0.
Fast Back-to-Back Enable: As a master, the GXm processor does not support this function.
This bit returns 0.
SERR# Enable: This is used as an output enable gate for the SERR# driver.
Wait Cycle Control: GXm processor does not do address/ data stepping.
This bit is always set to 0.
Parity Error Response:
0 = GXm processor ignores parity errors on the PCI bus.
1 = GXm processor checks for parity errors.
VGA Palette Snoop: GXm processor does not support this function.
This bit is always set to 0.
Memory Write and Invalidate Enable: As a master, the GXm processor does not support this function.
This bit is always set to 0.
Special Cycles: GXm processor does not respond to special cycles on the PCI bus.
This bit is always set to 0.
Bus Master:
0 = GXm processor does not perform master cycles on the PCI.
1 = GXm processor can act as a bus master on the PCI.
Memory Space: GXm processor will always respond to memory cycles on the PCI.
This bit is always set to 1.
I/O Space: GXm processor will not respond to I/O accesses from the PCI.
This bit is always set to 1.
PCI Device Status Register (RO, R/W Clear)
Default Value = 0280h
Detected Parity Error: When a parity error is detected, this bit is set to 1.
This bit can be cleared to 0 by writing a 1 to it.
Signaled System Error: This bit is set whenever SERR# is driven active.
Received Master Abort: This bit is set whenever a master abort cycle occurs. A master abort will occur
whenever a PCI cycle is not claimed except for special cycles.
This bit can be cleared to 0 by writing a 1 to it.
Received Target Abort: This bit is set whenever a target abort is received while the GXm processor is
master of the cycle.
This bit can be cleared to 0 by writing a 1 to it.
Signaled Target Abort: This bit is set whenever the GXm processor signals a target abort. A target
abort is signaled when an address parity occurs for an address that hits in the GXm processor’s address
space.
This bit can be cleared to 0 by writing a 1 to it.
Devise Timing:
00 = Fast
01 = Medium
10 = Slow
11 = Reserved
The GXm processor performs medium DEVSEL# active for addresses that hit into the GXm processor
address space. These two bits are always set to 01.
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