extern byte getch(void);
extern byte getchar(void);      //this is same as getch!!
extern byte kbhit(void);
extern byte key_tab;  // a 128byte array (scan code on =1 )
                      //   any key (grey or not) (key_tab1 OR key_tab2)
extern byte key_tab1;  // a 128byte array (scan code on =1 ) Non-grey keys 
extern byte key_tab2;  // a 128byte array (scan code on =1 ) Grey keys 
extern void key_block(byte x);