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PC-DIO-96 User Manual vi © National Instruments Corporation
Chapter 4
Register-Level Programming
......................................................................................... 4-1
Introduction ................................................................................................................... 4-1
Register Map ................................................................................................................. 4-2
Register Descriptions .................................................................................................... 4-3
Register Description for the 82C55A ................................................................ 4-3
Register Description for the 8253 ..................................................................... 4-4
Register Description for the Interrupt Control Registers .................................. 4-5
Interrupt Control Register 1 .................................................................. 4-6
Interrupt Control Register 2 .................................................................. 4-8
Programming Considerations for the 82C55A .............................................................. 4-9
Modes of Operation for the 82C55A ................................................................. 4-9
Mode 0 ................................................................................................... 4-9
Mode 1 ................................................................................................... 4-9
Mode 2 ................................................................................................... 4-10
Single Bit Set/Reset Feature .................................................................. 4-10
Mode 0—Basic I/O ........................................................................................... 4-10
Mode 0 Programming Example ............................................................ 4-11
Mode 1—Strobed Input ..................................................................................... 4-12
Mode 1 Input Programming Example ................................................... 4-14
Mode 1—Strobed Output .................................................................................. 4-15
Mode 1 Output Programming Example ................................................ 4-16
Mode 2—Bidirectional Bus............................................................................... 4-17
Mode 2 Programming Example ............................................................ 4-19
Interrupt Programming Examples for the 82C55A ........................................... 4-19
Programming Considerations for the 8253 ................................................................... 4-21
General Information .......................................................................................... 4-21
Interrupt Programming Example for the 8253 .................................................. 4-22
Interrupt Handling ......................................................................................................... 4-28
Appendix A
Specifications
........................................................................................................................ A-1
Appendix B
OKI 82C55A Data Sheet
.................................................................................................. B-1
Appendix C
AMD 8253 Data Sheet
....................................................................................................... C-1
Appendix D
Customer Communication
.............................................................................................. D-1
Glossary ...................................................................................................................... Glossary-1
Index.................................................................................................................................. Index-1