REDTEST.C

#include <dos.h>
#include <stdlib.h>
#include <stdio.h>
unsigned short int far *Video = (unsigned short int far *)MK_FP(0xA000, 0x0000);
unsigned short loopbreak = 0;
unsigned incx = 0;
unsigned incy = 0;
unsigned short inccolor = 0;

void setpixel(unsigned x, unsigned y, unsigned short color){

/*set initial values for what segment to write to*/

unsigned int segment = 0xA000;
unsigned int offset = 0x0000;

/* first ensure that the pixel is within bounds */

if(x > 319 || y > 199){
return;
}

/* now calculate segments and offset for x and y */

segment = segment + (20 * y);
offset = x;

/* now set the pointer to the needed location and write the pixel*/

Video = (unsigned short int far *)MK_FP(segment, offset);
*Video = color;
}

void gameloop(){
setpixel(incx,incy,12);
incx++;
if(incx == 319 && incy == 199){
loopbreak = 1;
return;
}
if(incx == 319){
incy++;
incx = 0;
}

}

int main(void){
    unsigned short incpal = 1;
    /* do initializations*/
    printf("\nThis test will slowly fill the screen with red");
    printf("\nPress enter to continue...");
    getchar();
    _AH = 0x00;
    _AL = 0x13;
    geninterrupt(0x10);
    while(loopbreak == 0){
    gameloop();
    delay(1);
    }
    getchar();
}