//向屏幕输出"Hello,world!"
#define black 0
#define blue 1
#define green 2
#define cyan 3
#define red 4
#define magenta 5
#define brown 6

void write_string(char *pstring,int color)
{
 char *pvideo=(char *)0xB8000000;
 while(*pstring)
 {
      *pvideo=*pstring;
        pstring++;
  pvideo++;
      *pvideo=color;
        pvideo++;
 }
}

void main()
{
 write_string("Hello,world!",red);
}