W83C553F Datasheet, PDF (98/159 Pages) Winbond – SYSTEM I/O CONTROLLER WITH PCI ARBITER

W83C553F
Electrical Specifications
Operational Control Word 2 Register
Function:
The Operational Control Word 2 (OCW2) Register controls both the Rotate Mode, End of Interrupt
Mode and combinations of the two.
Type:
Write Only
Bit Description:
Bits [7:5]:
Bits [4:3]:
Bits [2:0]:
ROT, SELLEVEL and EOI. These three bits control the Rotate, End of Interrupt (EOI) Modes
and combinations of the two, as shown below:
Bit 7
0
0
0
0
1
1
1
1
Bit 6
0
0
1
1
0
0
1
1
Bit 5
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])
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 2
0
0
0
0
1
1
1
1
Bit 1
0
0
1
1
0
0
1
1
Bit 0
0
1
0
1
0
1
0
1
Interrupt Level
IRQ0 (8)
IRQ1 (9)
IRQ2 (10)
IRQ3 (11)
IRQ4 (12)
IRQ5 (13)
IRQ6 (14)
IRQ7 (15)
WINBOND SYSTEMS LABORATORY
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