Chapter 4. Interrupt Controller
36
Initialization Register ICW4
0
0
7
6
5
4
3
2
1
0
0
1
Register: ICW4
Address: Base+1
End of interrupt
0 Normal
1 Automatic
Nesting mode
0 Standard
1 Special
0
AEOI
0
SFNM
Access:Write
Initialization Register ICW4
Operational Registers (OCW1-OCW3)
The operation of each interrupt controller is managed by three 8-bit operational registers. These
registers are programmed in any sequence for things such as enabling and disabling interrupt
requests and changing interrupt priorities. Illustrations of the three operational registers are presented
in the following topics.
Operational Register OCW1
Input Mask
7
6
5
4
3
2
1
0
Register: OCW1
Address: Base + 1
Interrupt mask
Access: Read and Write
0 Reset
1 Set
Operational Register OCW1
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