Intel 386 - Manual (Page 490)

16-11
INPUT/OUTPUT PORTS
16.4 PROGRAMMING CONSIDERATIONS
16.4.1 I/O Ports Code Example
The following code example contains a software routine that initializes the I/O port pins. See Ap-
pendix C for the included header files.
#include <conio.h>
#include “80386ex.h”
#include “ev386ex.h”
/*******************************************************************************
Init_IOPorts:
Description:
This function initializes the direction and mode of the I/O port pins.
Although the pins are default configured to the peripheral state after
RESET, they must still be initialized to turn off the weak resistors.
Parameters:
Port1 Port1 Mode Configuration
Port2 Port2 Mode Configuration
Port3 Port3 Mode Configuration
PortDir1 Port1 Direction
PortDir2 Port2 Direction
PortDir3 Port3 Direction
PortLtc1 Port1 Data Latch Value
PortLtc2 Port2 Data Latch Value
PortLtc3 Port3 Data Latch Value
Returns:
None
Assumptions:
None
Syntax:
// Port 1 configuration defines
#define DCD0 0x1
#define RTS0 0x2
#define DTR0 0x4
#define DSR0 0x8
#define RI0 0X10
#define LOCK 0x20
#define HOLD 0X40
#define HOLDACK 0X80
// Port 2 configuration defines
#define CS0 0x1
#define CS1 0x2