VT8601 Apollo ProMedia
Revision 1.3 September 8, 1999
-38-
Device 0 Bus 0 Host Bridge Registers
7HFKQRORJLHV ,QF
:H&
:H&RRQQHFW
QQHFW
Device 0 Offset 55-54 - Non-Cacheable Region #1 .........RW
15-3 Base Address - A<28:16>........................... default=0
As noted below, the base address must be a multiple
of the region size.
2-0
Range (Region Size)
000 Disable ...................................................default
001 64K
010 128K (Base Address A16 must be 0)
011 256K (Base Address A16-17 must be 0)
100 512K (Base Address A16-18 must be 0)
101 1M (Base Address A16-19 must be 0)
110 2M (Base Address A16-20 must be 0)
111 4M (Base Address A16-21 must be 0)
Device 0 Offset 57-56 - Non-Cacheable Region #2 .........RW
15-3 Base Address MSBs - A<28:16>................ default=0
As noted below, the base address must be a multiple
of the region size.
2-0
Range (Region Size)
000 Disable ...................................................default
001 64K
010 128K (Base Address A16 must be 0)
011 256K (Base Address A16-17 must be 0)
100 512K (Base Address A16-18 must be 0)
101 1M (Base Address A16-19 must be 0)
110 2M (Base Address A16-20 must be 0)
111 4M (Base Address A16-21 must be 0)
DRAM Control
These registers are normally set at system initialization time
and not accessed after that during normal system operation.
Some
of
these
registers,
however,
may
need
to
be
programmed using specific sequences during power-up
initialization to properly detect the type and size of installed
memory (refer to the VIA Technologies VT8601 BIOS
porting guide for details).
Table 3. System Memory Map
Space Start
Size
Address Range
Comment
DOS
0
640K 00000000-0009FFFF
Cacheable
VGA 640K
128K 000A0000-000BFFFF
Used for SMM
BIOS 768K
16K
000C0000-000C3FFF
Shadow Ctrl 1
BIOS 784K
16K
000C4000-000C7FFF
Shadow Ctrl 1
BIOS 800K
16K
000C8000-000CBFFF
Shadow Ctrl 1
BIOS 816K
16K
000CC000-000CFFFF Shadow Ctrl 1
BIOS 832K
16K
000D0000-000D3FFF
Shadow Ctrl 2
BIOS 848K
16K
000D4000-000D7FFF
Shadow Ctrl 2
BIOS 864K
16K 000D8000-000DBFFF Shadow Ctrl 2
BIOS 880K
16K 000DC000-000DFFFF Shadow Ctrl 2
BIOS 896K
64K
000E0000-000EFFFF
Shadow Ctrl 3
BIOS 960K
64K
000F0000-000FFFFF
Shadow Ctrl 3
Sys
1MB
—
00100000-DRAM Top Can have hole
Bus
D Top
DRAM Top-FFFEFFFF
Init
4G-64K 64K FFFEFFFF-FFFFFFFF 000Fxxxx alias
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