10     *   =    $600›20 HATABS  =    $031A›40 START   LDY  #0›60 LOOP    LDA  HATABS,Y›70         CMP  #0  ;  FREE ENTRY?›80         BEQ  FOUND›90         INY›0100       INY›0110       INY ;  POINT TO NEXT HATABS ENTRY›0120       CPY  #34  ;  AT END OF HATABS?›0130       BNE  LOOP  ;  NO ... CONTINUE›0140       SEC  ;  YES... INDICATE ERROR›0150       RTS›0160 ;›0180 FOUND LDA  #'N ;  SET DEVICE NAME›0190       STA  HATABS,Y›0200       INY›0210       LDA  #NULLTAB&255›0220       STA  HATABS,Y  ;  HANDLER ADDRESS›0230       INY›0240       LDA  #NULLTAB/256›0250       STA  HATABS,Y›0260       RTS›0270 ;›0290 NULLTAB .WORD  RTHAND-1   ;  OPEN›0300         .WORD  RTHAND-1   ;  CLOSE›0310         .WORD  NOFUNC-1   ;  READ›0320         .WORD  RTHAND-1   ;  WRITE›0330         .WORD  RTHAND-1   ;  STATUS›0340         .WORD  NOFUNC-1   ;  SPECIAL›0350         JMP    RTHAND     ;  INITILIZATION›0360 ;›0380 RTHAND  LDY  #1  ;  SUCCESSFUL I/O FUNCTION›0400 NOFUNC  RTS  ;  FUNCTION NOT IMPLEMENTED›