82C55A Datasheet, PDF (14/23 Pages) Intel Corporation – CHMOS PROGRAMMABLE PERIPHERAL INTERFACE

82C55A
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Figure 13 MODE Control Word
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Figure 14 MODE 2
Figure 15 MODE 2 (Bidirectional)
NOTE
Any sequence where WR occurs before ACK and STB occurs before RD is permissible
(INTR e IBF  MASK  STB  RD a OBF  MASK  ACK  WR)
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