10moveabs=4
   20linerel=1
   21TRIrel=linerel+80
   30moverel=0
   40DIM ox 3,oy 3
   50DIM Code 511
   60PROCassemble
   70PROC_init
   80PROC_main
   90END
  100DEFPROC_cursor
  110   MOVE OX,OY
  120   VDU 128
  130ENDPROC
  140 
  150DEFPROC_init
  160OX = 0:OY = 0:X = 0:Y = 0:!ox=OX:!oy=OY
  170MODE1
  180   VDU 5,18,3,1,23,128,0,24,60,126,24,24,24,0
  190ENDPROC
  200 
  210DEFPROC_track
  220   X=ADVAL(1): Y=ADVAL(2)
  230   X = (1024 - (X DIV 64)) * 1280 DIV 1024: Y = Y DIV 64
  240   X = X DIV 16 * 16: Y = Y DIV 20 * 20
  250ENDPROC
  260 
  270DEFPROC_main
  280   REPEAT
  290      A%=USR(cursor)
  300      !ox = X:!oy = Y
  310      REPEAT PROC_track: UNTIL X<>!ox OR Y<>!oy
  320      IF (ADVAL(0) AND 1) <> 0 THEN A%=USR(cursor)
  330      A%=USR(cursor)
  340      !ox = X:!oy = Y
  350   UNTIL FALSE
  360ENDPROC
  370DEFPROCassemble
  380FOR Pass=0 TO 2 STEP 2
  390OSWRCH=&FFEE
  400P%=Code
  410[OPT Pass
  420.cursor
  430]
  440PROCplot(moveabs):PROCvar(ox):PROCvar(oy)
  442PROCplot(linerel):PROCconst(50):PROCconst(0)
  444PROCplot(linerel):PROCconst(0):PROCconst(-50)
  448PROCplot(linerel):PROCconst(-50):PROCconst(0)
  450PROCplot(linerel):PROCconst(0):PROCconst(50)
  600   [OPT Pass:Rts:]
  610NEXT Pass
  620ENDPROC
  630 
  640DEFPROCvar(Addr)
  650[OPT Pass
  660   Lda Addr
  670   Jsr OSWRCH
  680   Lda Addr+1
  690   Jsr OSWRCH
  700]
  710ENDPROC
  720 
  730DEFPROCvdu(C%)
  740[OPT Pass
  750   Lda #C%
  760   Jsr OSWRCH
  770]
  780ENDPROC
  790 
  800DEFPROCplot(plotcode)
  810   PROCvdu(25)
  820   PROCvdu(plotcode)
  830ENDPROC
  840 
  850DEFPROCconst(X%)
  860X% = (X% AND &FFFF)
  870   PROCvdu(X% MOD 256)
  880   PROCvdu(X% DIV 256)
  890ENDPROC