vga-logic-processor-examples/simple.c

#include <i86.h>
#include <dos.h>
#include <conio.h>

int main(void) {
  union REGS regs;

  regs.w.ax = 0x13;

  int386(0x10, &regs, &regs);

  delay(5000);

  *((unsigned char far *)0xa0000 + (320 * 10) + 10) = 15;

  delay(2000);

  regs.w.ax = 0x03;

  int386(0x10, &regs, &regs);

  return 0;
}