8259A Datasheet, PDF (13/24 Pages) Intel Corporation – PROGRAMMABLE INTERRUPT CONTROLLER

8259A
OPERATION COMMAND WORDS
(OCWS)
After the Initialization Command Words (ICWs) are
programmed into the 8259A the chip is ready to ac-
cept interrupt requests at its input lines However
during the 8259A operation a selection of algo-
rithms can command the 8259A to operate in vari-
ous modes through the Operation Command Words
(OCWs)
Operation Control Words (OCWs)
OCW1
A0
D7 D6 D5 D4 D3 D2 D1 D0
1
M7 M6 M5 M4 M3 M2 M1 M0
OCW2
0
R SL EOI 0 0 L2 L1 L0
OCW3
0
0 ESMM SMM 0 1 P RR RIS
231468 – 15
Figure 8 Operation Command Word Format
231468 – 16
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