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© National Instruments Corporation
3-1
PC-DIO-24 User Manual
Chapter 3
Theory of Operation
This chapter contains a functional overview of the PC-DIO-24 board and explains the operation
of each functional unit making up the PC-DIO-24.
The block diagram in Figure 3-1 illustrates the key functional components of the PC-DIO-24
board.
I/O Connector
Interrupt
Control
Circuitry
82C55A
PPI
PC I/O
Channel
Control
Circuitry
Address
Decoder
Bus
Transceivers
PA
PB
PC
/
8
/
8
/
8
PC3
PC0
+5 V
PC I/O Channel
1 A Fuse
Figure 3-1. PC-DIO-24 Block Diagram
The PC I/O Channel consists of an address bus, a data bus, interrupt lines, and several control
and support signals. Control and data transfers to the system microprocessor are asynchronous.
Summary of Contents for PC-DIO-24
Page 51: ...Appendix C OKI 82C55A Data Sheet PC DIO 24 User Manual C 2 National Instruments Corporation...
Page 52: ...Appendix C OKI 82C55A Data Sheet National Instruments Corporation C 3 PC DIO 24 User Manual...
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Page 54: ...Appendix C OKI 82C55A Data Sheet National Instruments Corporation C 5 PC DIO 24 User Manual...
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Page 56: ...Appendix C OKI 82C55A Data Sheet National Instruments Corporation C 7 PC DIO 24 User Manual...
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Page 60: ...Appendix C OKI 82C55A Data Sheet National Instruments Corporation C 11 PC DIO 24 User Manual...
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