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Appendix C. Digital I/O
One of the characteristics of digital circuit is its fast response to
high or low signal. This kind of response is highly needed for
harsh and critical industrial operating environment. ROCKY-
6160 is designed with 4-bit digital inputs and 4-bit digital
outputs.
Two kinds of signals (Input and output) are used by the Digital
I/O function .These signals are used to control external devices
that need On/Off circuit or TTL devices. When one of the signals
has been selected, the user can read or write data to the
system through the Digital I/O function.
A BIOS function call (INT 15H) is served for the control of the
Digital I/O function.
1. To read data:
AH - 6FH
Sub-function:
AL
- 8:
to read data from input port
Return:
AL :
the data on the input port (lower 4 bit)
Example program:
MOV AX, 6F08H
; reading data form the digital input port
INT
15H
;
after return, input value will be stored
in the lower 4-bit of
AL
Содержание ROCKY-6160
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