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G
Architecture Overview
(Continued)
1.1.7.3
The name of this bit differs from that described in the
GX1
Processor Series datasheet
. There, it is called SDBE. Oth-
erwise, the functionality is the same as the standalone GX1
processor, See Table 1-2.
Slave PCI Burst Length Control
1.1.7.4
The
GX1 Processor Series datasheet
allows additional
sizes of 3 KB and 4 KB, which are disallowed in the
SC1100, see Table 1-3.
Scratchpad Size Control
1.1.7.5
The registers detailed in Table 1-4 must be set as indicated
in order for the SC1100 to function properly.
Disable Virtual VGA
1.1.7.6
In order for the SC1100 to function correctly, the Display
Controller
Configuration
(GX_BASE+Offset 8300h-830Fh) must all be set with 0s.
Disable Display Controller
and
Status
registers
Table 1-2. Slave PCI Burst Length Control
Bit
Description
Index 41h
Width: Byte
PCI Control Function 2 Register (R/W)
Reset Value: 96h
1
Slave Disconnect Boundary Enable (SDBE1):
GX1 as a PCI slave:
Works in conjunction with bit 0 of the MCR register. For details see Section 3.2 on page 50.
Note:
When Slave Disconnect Boundary is disabled for Write, the cache should use Write Through Mode instead of
Write Back Mode. The Write Through Mode implies some overall performance degradation since all Writes go to
Memory. If the Write back Mode is used in this case, the cache coherency cannot be guaranteed.
Table 1-3. Scratchpad Size Control
Bit
Description
Index B8h
Width: Byte
Graphics Control Register (R/W)
Reset Value: 00h
3:2
Scratchpad Size:
Specifies the size of the scratchpad cache. Either a 0 KB or a 2 KB Scratchpad Size must be chosen.
For details, see the GX1 Processor Series datasheet.
Table 1-4. Disable Virtual VGA
Bit
Description
Index 20h
Width: Byte
PCR0: Performance Control 0 Register (R/W)
Reset Value: 07h
5
VGA Memory Write SMI Generation (VGAMWSI).
Must be set to 0.
Index B9h
Width: Byte
VGACTL Register (R/W)
Reset Value: 00h
2
1
0
SMI generation for VGA memory range B8000h to BFFFFh. Must be set to 0.
SMI generation for VGA memory range B0000h to B7FFFh. Must be set to 0.
SMI generation for VGA memory range A0000h to AFFFFh. Must be set to 0.
Index BAh-BDh
Width: DWORD
VGAM Register (R/W)
Reset Value: xxxxxxxxh
31:0
SMI generation for address range A0000h to AFFFFh. Must be set to all 0s.
Gx Based + Offset 8004h - 8007h
Width: DWORD
BC_XMAP_1 Register (R/W)
Reset Value: 00000000h
28
20
15
14
13
4
Graphics Enable for B8 Region (GEB8). Must be set to 0.
Graphics Enable for B0 Region (GEB0). Must be set to 0.
SMID: All I/O accesses for address range 3D0h to 3DFh generate an SMI. Must be set to 0.
SMIC: All I/O accesses for address range 3C0h to 3CFh generate an SMI. Must be set to 0.
SMIB: All I/O accesses for address range 3B0h to 3BFh generate an SMI. Must be set to 0.
Graphics Enable for A Region (GEA). Must be set to 0.