W83C553FY-G Nuvoton Technology Corporation of America, W83C553FY-G Datasheet - Page 56

• Manufacturer Part Number: W83C553FY-G
• Manufacturer: Nuvoton Technology Corporation of America

Specifications of W83C553FY-G

• Lead Free Status / RoHS Status: Compliant

W83C553F
ISA-to-PCI Address Decoder Control Register (default = 01h)
Type:
Bit Description:
WINBOND SYSTEMS LABORATORY
Bits [7:4]:
Bit 3:
Bit 2:
Bit 1:
Bit 0:
Read/Write
IPATOM [3:0]. Top of Main Memory. Defines the top of memory for ISA memory space. ISA
memory accesses from 1 MByte to top of memory (except "hole") and above 16 MByte are
forwarded to the PCI bus.
MBELBIOS. Low BIOS Memory Block Enable; 896-960 KByte (E0000-EFFFFh). When set to
"1", ISA memory accesses in this range are forwarded to the PCI bus. The LBIOSCSE bit
(UBCSA, configuration register 4Dh bit 6) overrides this bit.
MBEVGA. VGA Memory Block Enable; 640-768 KByte (A0000-BFFFF). When set to "1", ISA
memory accesses in this range are forwarded to the PCI bus.
MBE640. Memory Block Enable; 512-640 KByte (80000-9FFFFh). When set to "1", ISA
memory accesses in this range are forwarded to the PCI bus.
MBE512. Memory Block Enable; 0-512 KByte (0-7FFFFh). When set to "1", ISA memory
accesses in this range are forwarded to the PCI bus. This bit is set to "1" after reset.
Bit 7
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
Bit 6
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
Bit 5
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
Bit 4
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Top of Memory
1 MByte
2 MByte
3 MByte
4 MByte
5 MByte
6 MByte
7 MByte
8 MByte
9 MByte
10 MByte
11 MByte
12 MByte
13 MByte
14 MByte
15 MByte
16 MByte
Electrical Specifications
63