10 REM Bubbles
   20 :
   30 VDU23,255,120,204,204,120,0,0,0,0
   40 :
   50 DIM code% 1024
   60 FOR loop=0 TO 2 STEP 2
   70 P%=code%
   80 [OPT loop
   90  
  100 .xlo   OPT FNreserve(10)
  110 .xhi   OPT FNreserve(10)
  120 .ylo   OPT FNreserve(10)
  130 .yhi   OPT FNreserve(10)
  140 .speed OPT FNreserve(10)
  150  
  160 .stars
  170    LDA #18
  180    JSR &FFEE
  190    LDA #3
  200    JSR &FFEE
  210    LDA #1
  220    JSR &FFEE
  230    JSR display
  240  
  250 .stars_loop
  260    JSR display
  270    JSR move
  280    JSR display
  290    LDA #&81
  300    LDY #&FF
  310    LDX #&9D
  320    JSR &FFF4
  330    CPY #&FF
  340    BNE stars_loop
  350    RTS
  360  
  370 .display
  380    LDX #0
  390 .display_loop
  400    LDA #25
  410    JSR &FFEE
  420    LDA #4
  430    JSR &FFEE
  440    LDA xlo,X
  450    JSR &FFEE
  460    LDA xhi,X
  470    JSR &FFEE
  480    LDA ylo,X
  490    JSR &FFEE
  500    LDA yhi,X
  510    JSR &FFEE
  520    LDA #255
  530    JSR &FFEE
  540    INX
  550    CPX#10
  560    BNE display_loop
  570    RTS
  580  
  590 .move
  600    LDX #0
  610 .move_loop
  620    LDA ylo,X
  630    CLC
  640    ADC speed,X
  650    STA ylo,X
  660    LDA yhi,X
  670    ADC #0
  680    CMP #5
  690    BNE not
  700    LDA #0
  710 .not
  720    STA yhi,X
  730    INX
  740    CPX #10
  750    BNE move_loop
  760    RTS
  770  
  780 ]:NEXT
  790 :
  800 FOR loop=0 TO 9
  810 loop?xlo=RND(256)-1
  820 loop?ylo=RND(256)-1
  830 loop?speed=RND(20)+10
  840 loop?xhi=2
  850 loop?yhi=RND(4)-1
  860 NEXT
  870  
  880 MODE0
  890 VDU23;8202;0;0;0;5
  900 CALLstars
  910 CHAIN"Disk"
  920  
  930 DEF FNreserve(bytes)
  940 P%=P%+bytes
  950 =loop