extern void set_mode(unsigned char );
extern void bios_pixel(short int ,short int ,unsigned char );
extern void set_pixel(unsigned char ,unsigned char,unsigned char );
extern void hor_line(unsigned char ,unsigned char ,unsigned char ,unsigned char );
extern void vert_line(unsigned char ,unsigned char ,unsigned char );
extern void fill_rect(unsigned char ,unsigned char ,unsigned char ,unsigned char ,unsigned char );
extern void inverse_buf(void);
extern void clear_buf(void);
extern void lineto(int ,int ,int ,int ,int );
extern void copy_to_lcd(void);