#include <dos.h> //for register definitions 'regs'

char *video_buffer = (char *)0xa0000; //Pointer to the start of video memory

void set_video_mode(int mode)
{
union REGS regs;
regs.x.ax = mode;
int86(0x10, &regs, &regs); //DOS inturrupt to set video mode
}

void main()
{
__djgpp_nearptr_enable();//DJGPP specific, don't worry about this
set_video_mode(0x013);

//Could draw pixels here

set_video_mode(0x03);
__djgpp_nearptr_disable();//DJGPP specific, don't worry about this
}

//Complile this program with this command: GCC EX1.C -O EX1.EXE -LM