w83c554f Winbond Electronics Corp America, w83c554f Datasheet - Page 95

• Manufacturer Part Number: w83c554f
• Description: System I/o Controller With Pci Arbiter & Ultradma/33 Ide Controller
• Manufacturer: Winbond Electronics Corp America

W83C554F
Operational Control Word 2 Register
Function:
Type:
Bit Description:
WINBOND ELECTRONICS CORP. AMERICA
Bits [7:5]:
Bits [4:3]:
Bits [2:0]:
The Operational Control Word 2 (OCW2) Register controls both the Rotate Mode, End of Interrupt
Mode and combinations of the two.
Write Only
ROT, SELLEVEL and EOI. These three bits control the Rotate, End of Interrupt (EOI) Modes
and combinations of the two, as shown below:
OCW2SEL[1:0]. OCW2 Selects. When selecting OCW2, these bits must be "00." If bit 4 is
"1," the interrupt controller interprets the write to this port as an ICW1.
LEVEL[2:0]. These bits determine the interrupt level acted upon when the SC bit (6) is active,
as shown below.
Bit 7
Bit 2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
Bit 6
Bit 1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
Bit 5
Bit 0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Mode
Rotate in Automatic EOI Mode (clear).
Non-specific EOI command
No operation
Specific EOI command
Rotate in Automatic EOI Mode (set)
Rotate on non-specific EOI command
*Set Priority Command
*Rotate on specific EOI command
*Level 0 - Level 2 are used (bits [2:0])
Interrupt Level
IRQ0 (8)
IRQ1 (9)
IRQ2 (10)
IRQ3 (11)
IRQ4 (12)
IRQ5 (13)
IRQ6 (14)
IRQ7 (15)
Register Information
93