w83c553f Winbond Electronics Corp America, w83c553f Datasheet - Page 71

• Manufacturer Part Number: w83c553f
• Description: System I/o Controller With Pci Arbiter
• Manufacturer: Winbond Electronics Corp America

W83C553F
AT System Control Register (default = 04h)
Type:
Bit Description:
WINBOND SYSTEMS LABORATORY
Bit 7:
Bit 6:
Bit 5:
Bit 4:
Bit 3:
Bit 2:
Bit 1:
Bit 0:
Read/Write
Reserved.
ISA Refresh Enable.
Reserved, always 0.
FERR# Enable. If this bit is set to "1," pin 12 will function as the Numeric Co-processor error
input.
Reserved.
P92E. Port 92 Enable. When enabled, access to Port 92 is enabled. When disabled, cycle will
be passed to the ISA bus.
Keyboard RC Emulation Enable. In x86 mode, this bit decodes the keyboard reset command
and generates INIT for at more than 4 PCI clocks. In PowerPC mode, this bit decodes the
keyboard reset command and generates HRESET# for 1ms.
Keyboard Gate A20 Emulation Enable. This bit toggles the Gate A20 output in x86 mode,
depending on the keyboard command.
Electrical Specifications
68