
Register Descriptions
Register Map
Copyright 1997-2000, V3 Semiconductor Inc.
EPC User
’
s Manual Revision 1.05
149
LB_BASE 0,1 : LOCAL BUS TO PCI BUS APERTURE 0,1 ADDRESS
Mnemonic:
Offset:
Size:
LB_BASE0, 1
54H, 58H
32 bits
LB_BASE0, 1
Bits
Mnemonic
Type
Reset
Value
Description
31-20
ADR_BASE
FRW
0H
Base Address: If the value of ADR_BASE matches that of local
address bits 31:20 during the address phase of a local access
then a match is detected. Since bits 31-20 are significant to the
decoder, the size of the aperture is 1MB. The aperture size can
be increased using the corresponding ADR_SIZE register bits so
that lower bits of the decode are masked off.
reserved
Byte Swap Control: Selects byte lane swapping for read and
write cycles according to the following table:
19-10
-
R
0H
9-8
SWAP
FRW
0H
Auto Swap: When local bus BE[3:0] =
“
1100
”
or
“
0011
”
then a 16
bit swap is done. When local bus BE[3:0] =
“
1110
”
,
“
1101
”
,
“
1011
”
or
“
0111
”
then an 8 bit swap is done. Any other combination
results in non-swapped data.
7-4
ADR_SIZE
FRW
0H
Aperture Size: The size of the aperture is determined as follows:
3
PREFETCH
FRW
0H
Prefetch Enable:
1 = enable the aperture for read prefetching
0 = disable read prefetching
reserved
1 = enable Local-to-PCI aperture 0.
0 = disable Local-to-PCI aperture 0.
2-1
-
R
0H
0
ENABLE
FRW
0H
SWAP
00
D[31:24]
Q[31:24]
D[23:26]
Q[23:16]
D[15:8]
Q[15:8]
D[7:0]
Q[7:0]
no swap, 32
bit
16 bit
8 bit
01
10
11
Q[15:8]
Q[7:0]
Q[7:0]
Q[15:8]
Q[31:24]
Q[23:16]
Q[23:16]
Q[31:24]
Auto Swap
ADDR_SIZE
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
a
1011
a
others
Size
1MB
2MB
4MB
8MB
16MB
32MB
64MB
128MB
256MB
512MB
1GB
2GB
Valid ADR BASE Bits
31:20
31:21
31:22
31:23
31:24
31:25
31:26
31:27
31:28
31:29
31:29
31:29
reserved
a.(The 1GB and 2GB aperture can be placed on a 512MB
boundary