#define	OS_NBR_LINES		50
#define	OS_NBR_COLUMNS		80

int	OS_key_pressed (void);
int	OS_get_key (void);
void	OS_clear_screen (void);
void	OS_locate (int x, int y);
void	OS_print (char	*text_0);
void	OS_print_at (int x, int y, char *text_0);
