Tandy 1000 HX Technical Reference Manual page 135

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).
Figure 8. Operation Command Word Format
2-246
Operation Control Words (OCWs)