W83C553F Datasheet, PDF (68/159 Pages) Winbond – SYSTEM I/O CONTROLLER WITH PCI ARBITER

W83C553F
Electrical Specifications
ISA-to-PCI Memory Hole Start Address Register (default = 00h)
Type:
Read/Write
Bit Description:
Bits [7:0]:
IPAHA. Memory Hole Start Address. These 8 bits specify the 8 most significant bits of the ISA
address: LA[23:16].
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
LA23 LA22 LA21 LA20 LA19 LA18 LA17 SA16
ISA-to-PCI Memory Hole Size Register (default = 00h)
Type:
Read/Write
Bit Description:
Bit 7:
Bits [6:0]:
IPAHE. Memory Hole Enable. When this bit is set to "1", access to the memory hole will not be
forwarded to the PCI bus. When this bit is reset to "0", access to the hole will be forwarded to
the PCI bus. The default value of this bit after a chip reset is "0".
IPAHS. Memory Hole Size. This field specifies the sizes of the memory hole according to the
following list:
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0
0
0
0
0
0
0 = 64 KBytes
0
0
0
0
0
0
1 = 125 KBytes
0
0
0
0
0
1
1 = 256 KBytes
0
0
0
0
1
1
1 = 512 KBytes
0
0
0
1
1
1
1 = 1 MBytes
0
0
1
1
1
1
1 = 2 MBytes
0
1
1
1
1
1
1 = 4 MBytes
1
1
1
1
1
1
1 = 8 MBytes
All other combinations are reserved.
WINBOND SYSTEMS LABORATORY
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