;›; Shooting stars by Dennis Fox›;››; Page zero usage››PBASE  =   $CB          ;POINTERS TO...›MBASE  =   $CD          ;MISSILES,›BASE2  =   $CF          ;PLAYER1,›BASE3  =   $D1          ;PLAYER2,›BASE4  =   $D3          ;PLAYER3,›ADDR   =   $D5          ;2-BYTE POINTER››; Page 6 usage››X      =   $600›Y      =   $601›XM     =   $610›YM     =   $620›DM     =   $630›T1     =   $640›T2     =   $641›TI1    =   $642›TI2    =   $643›HIT    =   $645›LIFE   =   $650›TI3    =   $660›TI4    =   $6A0›ELF    =   $6A1›SF1    =   $6A2›STIME  =   $6A3››; Operating system equates››ATTRAC =   $4D          ;ATTRACT MODE POINTER›PCOLR0 =   $2C0         ;PLAYER COLORS›PCOLR1 =   $2C1›PCOLR2 =   $2C2›PCOLR3 =   $2C3›COLOR0 =   $2C4         ;PLAYFIELD COLORS›COLOR1 =   $2C5›COLOR2 =   $2C6›COLOR3 =   $2C7›COLOR4 =   $2C8›SDMCTL =   $22F         ;DMA CONTROL›SDLSTL =   $230         ;DISP LIST POINTER›SDLSTH =   $231›STICK0 =   $278         ;JOYSTICK›STRIG0 =   $284         ;STICK BUTTON›HITCLR =   $D01E        ;COLLISION CLEAR›HPOSP0 =   $D000        ;P/M HOR. POSITIONS›HPOSP1 =   $D001›HPOSP2 =   $D002›HPOSP3 =   $D003›HPOSM0 =   $D004›HPOSM1 =   $D005›HPOSM2 =   $D006›HPOSM3 =   $D007›M1PL   =   $D009        ;COLLISION REGISTERS›M2PL   =   $D00A›M3PL   =   $D00B›P1PL   =   $D00D›P2PL   =   $D00E›P3PL   =   $D00F›GRACTL =   $D01D        ;GRAPHIC CONTROL›CONSOL =   $D01F        ;CONSOLE BUTTONS›AUDF1  =   $D200        ;AUDIO CONTROLS›AUDC1  =   $D201›AUDF2  =   $D202›AUDC2  =   $D203›RANDOM =   $D20A        ;RANDOM #›PMBASE =   $D407        ;P/M START ADDR›SETVBV =   $E45C        ;VERT BLANK SET VECTOR›XITVBV =   $E462        ;VERT BLANK EXIT››; set up screen and display list›› ORG $2000››SSTAR  LDX #9›       LDA #$FF›SETTB  STA SCRNA,X      ;SET TOP...›       STA SCRNC,X      ;AND BOTTOM...›       DEX              ;OF SCREEN›       BPL SETTB›       LDX #41›       LDA #SCRNB/256   ;POINT TO...›       STA ADDR+1       ;MIDDLE OF SCREEN›       LDA #SCRNB&255›       STA ADDR›SETMID LDY #9›MIDLP  LDA MIDBYT,Y     ;COPY MIDDLE BYTES...›       STA (ADDR),Y     ;TO SCREEN RAM›       DEY›       BPL MIDLP›       LDA ADDR         ;NOW ADD 10 BYTES...›       CLC              ;TO POINT TO...›       ADC #10          ;NEXT LINE›       STA ADDR›       LDA ADDR+1›       ADC #0›       STA ADDR+1›       DEX              ;ANOTHER LINE?›       BPL SETMID       ;YES!›       LDA #DLIST&255   ;POINT TO›       STA SDLSTL       ;DISPLAY›       LDA #DLIST/256   ;LIST›       STA SDLSTH›       LDA #$00         ;SET LOW BYTES...›       STA MBASE        ;OF P/M POINTERS›       STA PBASE›       STA BASE2›       STA BASE3›       STA BASE4›       LDA #$33         ;NOW SET HI BYTES›       STA MBASE+1      ;TO POINT TO›       LDA #$34         ;VARIOUS P/M AREAS›       STA PBASE+1›       LDA #$35›       STA BASE2+1›       LDA #$36›       STA BASE3+1›       LDA #$37›       STA BASE4+1››; Set players starting position››START2 LDA #16          ;INITIALIZE TIMERS›       STA TI1›       STA TI2›       STA TI4›       LDA #$00›       STA ELF›       STA SF1›       STA STIME›       STA TI3›       LDA #5           ;START W/5 LIVES›       STA LIFE›START  LDA #180         ;SET UP...›       STA X            ;ASTRONAUT X›       LDA RANDOM       ;NOW GET...›       LSR A            ;RANDOM #›       CLC              ;AND SET UP›       ADC #55          ;ASTRONAUT Y›       STA Y››; Set missles horizontal position››       LDX #$00         ;GET RANDOM...›L1     LDA RANDOM       ;HORIZONTAL›       LSR A            ;POSITION,›       LSR A            ;MAKE SURE IT'S›       ADC #50          ;ON SCREEN,›       STA XM,X         ;STORE IT›       INX              ;NEXT MISSILE›       CPX #6           ;ALL DONE?›       BNE L1           ;NOT YET!››; Set missles vertical position››       LDX #$00         ;START W/MISSILE 0›L2     TXA              ;GET MISSILE #›       ASL A            ;MULTIPLY...›       ASL A            ;MISSILE...›       ASL A            ;NUMBER...›       ASL A            ;BY 32,›       ASL A            ;MAKE SURE IT'S...›       ADC #55          ;ON SCREEN,›       STA YM,X         ;AND STORE IT!›       INX              ;NEXT MISSILE›       CPX #6           ;ALL DONE?›       BNE L2           ;NOT YET!››; Set missiles' starting directions››       LDX #$00›L3     LDA RANDOM       ;GET RANDOM...›       AND #$03         ;DIRECTION›       STA DM,X         ;AND STORE›       INX              ;NEXT MISSILE›       CPX #6           ;ALL DONE?›       BNE L3           ;NOT YET!››; Set up player missile graphics›; Single line resolution››       LDA #$30         ;POINT TO P/M AREA›       STA PMBASE›       LDA #62          ;TURN ON SCREEN›       STA SDMCTL›       LDA #3           ;SET P/M GRAPHICS›       STA GRACTL›       LDA #$00         ;NOW CLEAR OUT...›       TAY              ;ALL MISSILES›A1     STA (PBASE),Y    ;AND PLAYERS›       STA (MBASE),Y›       STA (BASE2),Y›       STA (BASE3),Y›       STA (BASE4),Y›       INY›       BNE A1›       LDA #$00         ;NO COLLISION!›       STA HIT›       STA HITCLR›       LDA #$46         ;SET UP COLORS›       STA PCOLR0›       LDA #15›       STA PCOLR1›       STA PCOLR2›       STA PCOLR3›       LDA #150›       STA COLOR1›       LDA #54›       STA COLOR2›       LDA #$F8›       STA COLOR0›       LDA #3›       STA T2›       LDA #$07         ;NOW START UP...›       LDX #VBI/256     ;OUR VERTICAL BLANK...›       LDY #VBI&255     ;INTERRUPT!›       JSR SETVBV››; The game begins here››BACK   LDA CONSOL       ;CHECK CONSOLE KEYS›       CMP #6           ;START PRESSED?›       BNE JOY2         ;NOPE!›       JMP DEATH        ;GO TO RESTART!››; Read joystick››JOY2   LDA STICK0       ;GET ASTRONAUT...›       AND #1           ;DIRECTION›       BNE O1›       DEC Y            ;UP›O1     LDA STICK0›       AND #$08›       BNE O2›       INC X            ;RIGHT›O2     LDA STICK0›       AND #$02›       BNE O3›       INC Y            ;DOWN›O3     LDA STICK0›       AND #$04›       BNE O4›       DEC X            ;LEFT›O4     LDA X            ;GET ASTRO. X›       CMP #200         ;TOO FAR RIGHT?›       BNE O5           ;IT'S OK›       DEC X            ;TOO FAR!›O5     LDA X›       CMP #50          ;TOO FAR LEFT?›       BNE O6           ;OK.›       INC X            ;TOO FAR!›O6     LDA Y            ;GET ASTRO. Y›       CMP #52          ;TOO FAR UP?›       BNE O7           ;OK.›       INC Y            ;TOO FAR!›O7     LDA Y›       CMP #200         ;TOO FAR DOWN?›       BNE O8           ;OK.›       DEC Y            ;TOO FAR!››; Put astronaut on playfield››O8     LDA X            ;GO AHEAD AND SET...›       STA HPOSP0       ;HOR. POSITION›       LDX #$00         ;NOW COPY THE...›       LDY Y            ;ASTRONAUT IMAGE...›B1     LDA ANAUT,X      ;INTO PLAYER 1›       STA (PBASE),Y›       INX›       INY›       CPX #19›       BNE B1››; Move missiles››       LDX #$00›D0     LDA DM,X         ;GET MISSILE DIR.›       BNE D1›       INC XM,X         ;RIGHT...›       DEC YM,X         ;AND UP›D1     LDA DM,X›       CMP #1›       BNE D2›       INC XM,X         ;RIGHT...›       INC YM,X         ;AND DOWN!›D2     LDA DM,X›       CMP #2›       BNE D3›       DEC XM,X         ;LEFT...›       INC YM,X         ;AND DOWN!›D3     LDA DM,X›       CMP #3›       BNE DO1›       DEC XM,X         ;LEFT...›       DEC YM,X         ;AND UP!›DO1    INX              ;NEXT MISSILE›       CPX #6           ;ALL DONE?›       BNE D0           ;NO, DO OTHERS!››; Check if missile has hit wall››       LDX #$00›C0     LDA XM,X         ;GET X POS.›       CMP #202         ;TOO FAR RIGHT?›       BNE C1           ;IT'S OK.›       LDA DM,X         ;IT'S TOO FAR,›       BNE DI1          ;WE MUST REVERSE›       LDA #3           ;THE DIRECTION!›       STA DM,X›       CLC›       BCC C1›DI1    LDA #2›       STA DM,X›C1     LDA XM,X         ;GET X POS.›       CMP #48          ;TOO FAR LEFT?›       BNE C2           ;OK.›       LDA DM,X         ;REVERSE DIRECTION!›       CMP #2›       BEQ DI2›       LDA #0›       STA DM,X›       CLC›       BCC C2›DI2    LDA #1›       STA DM,X›C2     LDA YM,X         ;GET Y POS.›       CMP #52          ;TOO FAR UP?›       BNE C3           ;OK.›       LDA DM,X         ;REVERSE!›       BNE DI3›       LDA #1›       STA DM,X›       CLC›       BCC C3›DI3    LDA #2›       STA DM,X›C3     LDA YM,X         ;GET Y POS.›       CMP #213         ;TOO FAR DOWN?›       BNE C4           ;OK.›       LDA DM,X         ;REVERSE!›       CMP #1›       BNE DY2›       LDA #$00›       STA DM,X›       CLC›       BCC C4›DY2    LDA #3›       STA DM,X›C4     INX              ;NEXT MISSILE›       CPX #6           ;ALL DONE?›       BNE C0           ;NO, DO OTHERS!››; Plot missiles on playfield››       LDA XM           ;SET ALL MISSILES...›       STA HPOSP1       ;HORIZONTAL...›       LDA XM+1         ;POSITIONS!›       STA HPOSP2›       LDA XM+2›       STA HPOSP3›       LDA XM+3›       STA HPOSM1›       LDA XM+4›       STA HPOSM2›       LDA XM+5›       STA HPOSM3›       LDA #$00         ;PLOT 1ST MISSILE›       LDY YM           ;IN PLAYER 1›       STA (BASE2),Y›       LDA #$10›       INY›       STA (BASE2),Y›       INY›       STA (BASE2),Y›       LDA #$00›       INY›       STA (BASE2),Y›       LDA #$00         ;PLOT 2ND MISSILE›       LDY YM+1         ;IN PLAYER 2›       STA (BASE3),Y›       LDA #$10›       INY›       STA (BASE3),Y›       INY›       STA (BASE3),Y›       LDA #$00›       INY›       STA (BASE3),Y›       LDA #$00         ;PLOT 3RD MISSILE›       LDY YM+2         ;IN PLAYER 3›       STA (BASE4),Y›       LDA #$10›       INY›       STA (BASE4),Y›       INY›       STA (BASE4),Y›       LDA #$00›       INY›       STA (BASE4),Y›       LDA #$EF         ;PLOT 4TH MISSILE›       LDY YM+3         ;IN MISSILE 1›       AND (MBASE),Y›       STA (MBASE),Y›       LDA #$10›       INY›       ORA (MBASE),Y›       STA (MBASE),Y›       LDA #$10›       INY›       ORA (MBASE),Y›       STA (MBASE),Y›       LDA #$EF         ;PLOT 5TH MISSILE›       INY              ;IN MISSILE 2›       AND (MBASE),Y›       STA (MBASE),Y›       LDA #$FB›       LDY YM+4›       AND (MBASE),Y›       STA (MBASE),Y›       LDA #$04›       INY›       ORA (MBASE),Y›       STA (MBASE),Y›       LDA #$04›       INY›       ORA (MBASE),Y›       STA (MBASE),Y›       LDA #$FB         ;PLOT 6TH MISSILE›       INY              ;IN MISSILE 3›       AND (MBASE),Y›       STA (MBASE),Y›       LDA #$BF›       LDY YM+5›       AND (MBASE),Y›       STA (MBASE),Y›       LDA #$40›       INY›       ORA (MBASE),Y›       STA (MBASE),Y›       LDA #$40›       INY›       ORA (MBASE),Y›       STA (MBASE),Y›       LDA #$BF›       INY›       AND (MBASE),Y›       STA (MBASE),Y››; Create sound››       INC T1›       LDA T1›       CMP #$10›       BNE SO1›       LDA #$00›       STA T1›       DEC T2›       LDA T2›       BNE SO2›       LDA #3›       STA T2›SO2    LDA #$C8         ;SET SOUND CONTROL›       STA AUDC2›       LDA T2           ;GET SOUND NUMBER›       CMP #3           ;SOUND 3?›       BNE S2           ;NO!›       LDA #120         ;SET 3RD...›       STA AUDF2        ;SOUND FREQUENCY›       CLC›       BCC SO1          ;GO SHOW TIME›S2     LDA T2›       CMP #2           ;SOUND 2?›       BNE S3           ;NO!›       LDA #100         ;SET 2ND...›       STA AUDF2        ;SOUND FREQUENCY›       CLC›       BCC SO1          ;AND SHOW TIME›S3     LDA #85          ;SET 1ST›       STA AUDF2        ;SOUNC FREQUENCY›SO1    LDA TI1          ;SHOW DIGIT 1...›       STA SCREEN+9     ;OF SECONDS›       LDA TI2          ;SHOW DIGIT 2...›       STA SCREEN+10    ;OF SECONDS›       LDA TI4          ;SHOW MINUTES!›       STA SCREEN+7››; Check for extra life››       LDA TI4          ;GET MINUTES›       CMP #19          ;3 MINUTES?›       BNE OELC         ;NO!›       LDA ELF          ;DONE EXTRA LIFE YET?›       BNE OELC         ;YES, NO MORE!›       INC LIFE         ;ANOTHER LIFE›       INC ELF          ;SET EXTRA LIFE FLAG›       LDA #$A4         ;SET UP FOR...›       STA AUDC1        ;EXTRA LIFE SOUND›       LDA #$01›       STA SF1›OELC   LDA TI4          ;GET MINUTES›       CMP #21          ;5 MINUTES?›       BNE OEL          ;NO!›       LDA ELF          ;GOT 2ND EXTRA?›       CMP #1›       BNE OEL          ;NO MORE!›       INC LIFE         ;ANOTHER LIFE!›       INC ELF          ;INC EXTRA LIFE FLAG›       LDA #$A4         ;SET UP FOR...›       STA AUDC1        ;EXTRA LIFE SOUND›       LDA #$01›       STA SF1››; Check for ending sequence››OEL    LDA HIT          ;ASTRO HIT DEBRIS?›       BEQ NEND         ;NO, HE'S OK.›       JMP END          ;UH-OH!›NEND   LDA #80          ;THIS SECTION›       LSR TI1          ;CREATES A TIME›       PHP              ;DELAY USING›       SEC              ;THE TIME VARIABLES›       SBC TI1          ;TI1 AND TI4›       PLP›       ROL TI1›       LDX #$00›SMOR   SBC TI4›       INX›       CPX #3›       BNE SMOR›       TAX›TD1    LDY #$00         ;THIS IS A›TD2    INY              ;TIME DELAY›       BNE TD2          ;ROUTINE!›       DEX›       BNE TD1››; Play extra life sound››       LDA SF1          ;GET BONUS SOUND FLAG›       CMP #1           ;FIRST FREQ?›       BNE SC2          ;NO!›       LDA #50          ;SET 1ST BONUS FREQ.›       STA AUDF1›       INC STIME        ;INC SOUND TIMER›       LDA STIME›       CMP #$25         ;END OF SOUND?›       BNE SC2          ;NOT YET!›       INC SF1          ;NEXT FREQ›       LDA #$00         ;NO MORE SOUND!›       STA STIME›SC2    LDA SF1          ;GET BONUS SOUND FLAG›       CMP #2           ;SECOND FREQ?›       BNE SC3          ;NO!›       LDA #40          ;SET FREQ.›       STA AUDF1›       INC STIME        ;INCREMENT TIMER›       LDA STIME›       CMP #$25         ;SOUND DONE?›       BNE SC3          ;NO!›       INC SF1          ;NEXT FREQ›       LDA #$00         ;ALL DONE!›       STA STIME›SC3    LDA SF1          ;GET BONUS SOUND FLAG›       CMP #3           ;3RD FREQ?›       BNE SC4          ;NO!›       LDA #32          ;SET FREQ.›       STA AUDF1›       INC STIME        ;INC SOUND TIMER›       LDA STIME›       CMP #$25         ;SOUND DONE?›       BNE SC4          ;NO!›       INC SF1          ;SET FOR END›       LDA #$00         ;ALL DONE!›       STA STIME›SC4    LDA SF1          ;GET BONUS SOUND FLAG›       CMP #4           ;END OF SOUND?›       BNE SC5          ;NO!›       LDA #00          ;SHUT OFF SOUND!›       STA AUDF1›       STA AUDC1›       LDA #$00         ;ALL DONE!›       STA STIME›SC5    LDA #138         ;UPDATE LIVES...›       LDX #$00         ;DISPLAY›DMORE  STA SCREEN+13,X  ;ALL LIVES›       INX›       CPX LIFE›       BNE DMORE›       JMP BACK›END    DEC LIFE         ;1 LESS LIFE›       LDA #$A8         ;INIT DEATH SOUND›       STA AUDC1›       STA AUDC2›       LDA #50          ;INIT FREQ.›SA     STA AUDF1›       PHA›       CLC›       ADC #100         ;INCREMENT SOUND›       STA AUDF2›       STA PCOLR0       ;FLASH ASTRONAUT›       PLA›       LDY #$00         ;TIME DELAY›DLY2   LDX #$00›DLY1   INX›       BNE DLY1›       INY›       CPY #25›       BNE DLY2›       CLC›       ADC #$01›       CMP #100         ;END OF DEATH?›       BNE SA           ;NO, LOOP BACK›       LDA #$00         ;SHUT OFF SOUND›       STA AUDF1›       STA AUDC1›       STA AUDF2›       STA AUDC2›       LDA #$46         ;RESET...›       STA PCOLR0       ;ASTRONAUT COLOR›       LDA #$00         ;REMOVE...›       LDY LIFE         ;LIFE INDICATOR...›       STA SCREEN+13,Y  ;FROM SCREEN›       LDA LIFE         ;ANY MORE LIVES?›       BEQ DEATH        ;NO! END OF GAME!›       JMP START        ;ANOTHER LIFE.›DEATH  LDA #00          ;ZERO LIVES›       STA LIFE›AGAIN  LDA STRIG0       ;STICK TRIGGER PRESSED?›       BEQ RESTRT       ;YES!›       LDA CONSOL       ;GET CONSOLE KEY›       CMP #6           ;START PRESSED?›       BNE AGAIN        ;NO!›RESTRT LDA #$00         ;RESET...›       STA ATTRAC       ;ATTRACT MODE›       JMP START2       ;RESTART GAME.››; Vertical blank interrupt››VBI    LDA M1PL         ;GET...›       ORA M2PL         ;ALL...›       ORA M3PL         ;COLLISION...›       ORA P1PL         ;REGISTERS...›       ORA P2PL         ;AND CHECK...›       ORA P3PL         ;FOR...›       AND #1           ;ASTRONAUT...›       STA HIT          ;COLLISION!›       INC TI3          ;INCREMENT 1/60 SEC.›       LDA TI3          ;TIMER›       CMP #60          ;ANOTHER SECOND?›       BNE TOVR         ;NO!›       LDA #$00         ;RESET 60THS OF SEC›       STA TI3›       INC TI2          ;ANOTHER SEC›       LDA TI2›       CMP #26          ;10 SECS?›       BNE TOVR         ;NO!›       LDA #16          ;RESET 2ND SECOND...›       STA TI2          ;DIGIT TO 0›       INC TI1          ;INCREMENT 1ST...›       LDA TI1          ;SECOND DIGIT›       CMP #22          ;GOT A MINUTE?›       BNE TOVR         ;NO!›       INC TI4          ;INCREMENT MINUTES›       LDA #16          ;RESET 1ST SECOND...›       STA TI1          ;DIGIT TO 0›TOVR   JMP XITVBV       ;EXIT VERT BLANK!››; Set up display list››DLIST  DB  112,112,112,71›       DW  SCREEN›       DB  9,9,9,9,9,9,9,9,9,9›       DB  9,9,9,9,9,9,9,9,9,9›       DB  9,9,9,9,9,9,9,9,9,9›       DB  9,9,9,9,9,9,9,9,9,9›       DB  9,9,9,9›       DB  65›       DW  DLIST››; Data for astronaut image››ANAUT  DB  $00,$7C,$54,$6C,$7C,$44,$7C,$10,$10,$FE,$BA,$BA›       DB  $BA,$38,$38,$28,$28,$EE,$00››; Set up screen memory››MIDBYT DB  128,0,0,0,0,0,0,0,0,1›SCREEN DB  0,0,116,105,109,101,0,0,26,0,0,0,0,0,0,0,0,0,0,0›SCRNA  DS  10›SCRNB  DS  420›SCRNC  DS  10››       END SSTAR›