#include <conio.h> #include <stdio.h> #include <dos.h> /* Type Definitions */ typedef unsigned char UBYTE; /* Old habbit... */ /* Serial Port Definitions */ #define STATUS 0x308 /* Status Base Address */ #define CONTROL 0x300 /* Control Base Address */ #define TXREG 0x30C /* Transmit Base Address */ #define RXREG 0x304 /* Receive Base Address */ #define TRUE 1 /* Function Prototypes */ void InitUSART(void); /* Initialize USART */ void TxData(UBYTE); /* Transmit Data */ UBYTE RxData(void); /* Receive Data */ /* InitUSART() - Initialize USART to 153600, 8 Data Bits, No Parity, 1 Stop Bit */ void InitUSART(void) { outp(CONTROL, 0x00); outp(CONTROL, 0x00); outp(CONTROL, 0x00); outp(CONTROL, 0x40); // Reset UART outp(CONTROL, 0x4E); // Stop, no parity, 8-bit, %16 baud outp(CONTROL, 0x05); // UART now ready } /* TxData() - Send Data to Serial Port Entry: data = Data to transmit */ void TxData(UBYTE data) { UBYTE x; /* Check for Tx Buffer Empty */ do { x = inp(STATUS); x &= 0x01; } while(x == 0); outp(TXREG, data); /* Send Data */ } /* RxData() - Receive Data from the Serial Port Exit: data = Rx Data byte */ UBYTE RxData(void) { UBYTE x; UBYTE data = 0; while(TRUE) /* Check for Rx Data */ { x = inp(STATUS); x &= 0x02; if(x == 0x02) { data = inp(RXREG); /* Get Data */ break; } /* Optional. Aborts if keypress */ if(kbhit()) /* Abort if Keypress */ { getch(); printf("\n"); break; } } return(data); } void main(void) { UBYTE DSR; InitUSART(); while(TRUE) putch(RxData()); }