Tandy 1000 HX Technical Reference Manual page 136

8259A
Operation Control Word 1 (0CW1)
0CW1 sets and clears the mask bits in the interrupt
Mask Register (IMR). M
7
- M
0
represent the eight
mask bits. M = 1 indicates the channel is masked
(inhibited), M = 0 indicates the channel is enabled.
Operation Control Word 2 (0CW2)
Ft, SL, EOI—These three bits control the Rotate and
End of Interrupt modes and combinations of the two.
A chart of these combinations can be found on the
Operation Command Word Format.
l_2, Li, Lo—These bits determine the interrupt level
acted upon when the SL bit is active.
Figure 8. Operation Command Word Format (Continued)
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