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Copy pathRaceInSpace.asm
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RaceInSpace.asm
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; +---------------+
; | RACE IN SPACE |
; +---------------+
;
; Written by Charles Bachand
;
ORIGIN = $1000
;
; Game Playfield Area
; -------------------
;
DRAM = ORIGIN+$1000
MRAM = DRAM+$1900
ASTR = PAGES*512+DRAM
ASTL = PAGES*256+ASTR
;
; Player/Missile Area
; -------------------
;
*= $0800
;
PM *= *+$0180 ;blank space
PMM *= *+$80 ;missiles
PM0 *= *+$80 ;player 0
PM1 *= *+$80 ;player 1
PM2 *= *+$80 ;player 2
PM3 *= *+$80 ;player 3
;
; System Equates
; --------------
;
TRAM = PM ;PM blank space
CHBAS = $02F4 ;char base reg
CH = $02FC ;last key press
VSCROL = $D405 ;vertical scroll
NMIEN = $D40E ;interrupt ctrl
VDSLST = $0200 ;DLI vector
SDMCTL = $022F ;DMA enable
SDLSTL = $0230 ;display list
COLOR0 = $02C4 ;color reg 0
COLOR1 = $02C5 ;color reg 1
COLOR2 = $02C6 ;color reg 2
COLPF1 = $D017 ;color playfld 1
DLI = $80 ;DLI flag
ATRACT = 77 ;attract mode
RTCLOK = 20 ;real time clock
PCOLR0 = $02C0 ;player color 0
PCOLR1 = $02C1 ;player color 1
PCOLR2 = $02C2 ;player color 2
PCOLR3 = $02C3 ;player color 3
GPRIOR = $026F ;priority
SIZEP2 = $D00A ;size player 2
SIZEP3 = $D00B ;size player 3
HPOSP0 = $D000 ;pos player 0
HPOSP2 = $D002 ;pos player 2
HPOSP3 = $D003 ;pos player 3
HPOSM0 = $D004 ;pos missile 0
SIZEM = $D00C ;missile size
VDELAY = $D01C ;vertical delay
GRACTL = $D01D ;graphics ctrl
CONSOL = $D01F ;console keys
PMBASE = $D407 ;P/M base addr
AUDF1 = $D200 ;audio freq 1
AUDF2 = $D202 ;audio freq 2
AUDF3 = $D204 ;audio freq 3
AUDF4 = $D206 ;audio freq 4
AUDC1 = $D201 ;audio volume 1
AUDC2 = $D203 ;audio volume 2
AUDC3 = $D205 ;audio volume 3
AUDC4 = $D207 ;audio volume 4
AUDCTL = $D208 ;audio control
SKCTL = $D20F ;serial ctrl
RANDOM = $D20A ;random number
STRIG = $0284 ;joystick trig 0
STICK = $0278 ;joystick 0
PAGES = $06 ;scrn block size
P0PF = $D004 ;P0/PF collision
P1PF = $D005 ;P1/PF collision
M0PL = $D008 ;M0/PL collision
M1PL = $D009 ;M1/PL collision
P0PL = $D00C ;P0/PL collision
P1PL = $D00D ;P1/PL collision
HITCLR = $D01E ;collision clear
PACTL = $D302 ;port A control
;
; Page Zero equates
; -----------------
;
*= $80
;
SELPNT *= *+2 ;menu select pnt
CONSAV *= *+1 ;console save
CLOCK *= *+1 ;local clock
SLINE *= *+1 ;scroll line cnt
VOLUME *= *+1 ;intro volume
DIRSW *= *+1 ;vol direction
OPTION *= *+1 ;OPTION key indx
OPTSW *= *+1 ;OPTION switch
TRIG *= *+1 ;Trigger option
DENS *= *+1 ;starfield dens
SHIP *= *+1 ;ship type
COME *= *+1 ;comet enabled
UNIV *= *+1 ;inverse univ
SOFSET *= *+1 ;SELECT offset
TEMP *= *+4 ;temp registers
GRPAGE *= *+2 ;screen pointer
GRP1 *= *+2 ;asteroid left
GRP2 *= *+2 ;asteroid right
GRP20P *= *+2 ;scrn pntr -20
GRPX *= *+2 ;player gr pntr
GRPM *= *+2 ;missile gr pntr
FLASHC *= *+1 ;univ flash cntr
FLASHF *= *+1 ;univ flash flag
REVF *= *+1 ;inv univ flag
HPOS *= *+1 ;comet H pos
HDIR *= *+1 ;comet H dir
HINC *= *+1 ;comet H speed
VPOS *= *+1 ;comet V pos
VDIR *= *+1 ;comet V dir
VINC *= *+1 ;comet V speed
DEAD *= *+2 ;dead ship flg
COMETF *= *+1 ;comet set flag
CSOUND *= *+1 ;comet snd cntr
UNIVS *= *+1 ;universe sound
ENDGAM *= *+1 ;game over flag
SCORES *= *+2 ;game scores
TRIGN *= *+2 ;processed trigs
TRIGS *= *+2 ;last triggers
ROTATE *= *+1 ;rotate index
SCLOCK *= *+1 ;score snd timer
VDEL *= *+1 ;vert delay
MISSLE *= *+2 ;shot flags
ROWAC *= *+2 ;shot row acc
DELTAR *= *+2 ;shot delta row
ENDPT *= *+2 ;shot end point
ROWCRS *= *+2 ;shot row cursor
ROWINC *= *+2 ;shot row inc
COLAC *= *+2 ;shot column acc
DELTAC *= *+2 ;delta column
COLCRS *= *+2 ;column cursor
COLINC *= *+2 ;shot column inc
COUNTR *= *+2 ;shot delta cnt
NEWCOL *= *+1 ;shot end column
NEWROW *= *+1 ;shot end row
OLDCOL *= *+1 ;shot old column
OLDROW *= *+1 ;shot old row
TEMPM *= *+1 ;shot temporary
M0PLS *= *+2 ;M0 col shadow
XPLR *= *+2 ;ship X coords
YPLR *= *+2 ;ship Y coords
;
*= ORIGIN
;
; Redefined Character Set Data
; ----------------------------
;
CHARS .BYTE 0,0,0,0,0,0,0,0
.BYTE 0,0,0,0,$7B,50,50,50
.BYTE 0,0,0,0,$60,$A0,$A0,32
.BYTE 0,$7E,66,66,$7E,66,66,0
.BYTE 0,$7E,64,64,64,64,$7E,0
.BYTE 0,$7C,70,70,70,70,$7C,0
.BYTE 0,$7E,64,$7C,64,64,$7E,0
.BYTE 0,$7E,64,$7C,64,64,64,0
.BYTE 0,$7E,64,64,78,66,$7E,0
.BYTE 0,66,66,$7E,66,66,66,0
.BYTE 0,$7E,24,24,24,24,$7E,0
.BYTE 0,64,64,64,64,64,$7E,0
.BYTE 0,$7E,66,66,66,66,66,0
.BYTE 0,$7E,66,66,$7E,64,64,0
.BYTE 0,$7E,66,66,$7E,76,70,0
.BYTE 0,$7E,24,24,24,24,24,0
.BYTE 0,66,66,66,90,90,$7E,0
.BYTE 0,66,66,$7E,24,24,24,0
.BYTE $7E,$81,$BD,$A1
.BYTE $A1,$BD,$81,$7E
.BYTE 0,$7E,66,66,66,66,$7E,0
.BYTE 0,8,8,8,8,8,8,0
.BYTE 0,$7E,2,$7E,64,64,$7E,0
.BYTE 0,$7E,2,$7E,2,2,$7E,0
.BYTE 0,66,66,$7E,2,2,2,0
.BYTE 0,$7E,64,$7E,2,2,$7E,0
.BYTE 0,$7E,64,$7E,66,66,$7E,0
.BYTE 0,$7E,2,2,2,2,2,0
.BYTE 0,$7E,66,$7E,66,66,$7E,0
.BYTE 0,$7E,66,$7E,2,2,$7E,0
.BYTE 0,0,0,0,0,0,0,0
.BYTE 24,36,90,0,0,0,0,0
.BYTE 0,0,24,60,60,24,0,0
.BYTE 0,0,0,60,$7E,$7E,$7E,60
.BYTE 0,0,0,0,$7E,$FF,$FF,$FF
.BYTE 0,0,0,0,0,60,$7E,$7E
.BYTE 0,0,0,0,0,0,24,60
.BYTE 0,0,0,0,0,0,0,24
.BYTE 0,0,0,0,0,0,0,0
.BYTE 0,0,0,0,0,0,0,0
.BYTE 0,0,0,0,0,0,0,0
.BYTE 60,0,0,0,0,0,0,0
.BYTE $FF,$FF,$FF,$7E,0,0,0,0
.BYTE $7E,$7E,60,0,0,0,0,0
.BYTE 60,24,0,0,0,0,0,0
.BYTE 24,0,0,0,0,0,0,0
.BYTE 0,24,24,24,24,60,$7E,90
.BYTE 24,24,24,60
.BYTE $7E,$FF,$DB,0
.BYTE 0,0,0,0,0,0,0,0
.BYTE 0,66,66,66,66,66,$7E,0
.BYTE 0,0,24,24,0,24,24,0
.BYTE 0,66,66,66,66,36,24,0
.BYTE 0,$7E,90,90,66,66,66,0
.BYTE 0,70,76,$78,88,76,70,0
.BYTE $FF,$FF,$FF,$FF
.BYTE $FF,$FF,$FF,$FF
.BYTE $7E,66,66,0,66,66,$7E,0
.BYTE 2,2,2,0,2,2,2,0
.BYTE 62,2,2,60,64,64,$7C,0
.BYTE 62,2,2,60,2,2,62,0
.BYTE 66,66,66,60,2,2,2,0
.BYTE $7C,64,64,60,2,2,62,0
.BYTE $7C,64,64,60,66,66,$7E,0
.BYTE 62,2,2,0,2,2,2,0
.BYTE $7E,66,66,60,66,66,$7E,0
.BYTE $7E,66,66,60,2,2,62,0
;
; Introduction Display List
; -------------------------
;
DISPI .BYTE $70,$67
DADR .WORD DRAM
.BYTE $27,$27,$27,$27
.BYTE $27,$27,$27,$27
.BYTE $27,$27,$27,$27
.BYTE $27,$07,$41+DLI
.WORD DISPI
;
; Game Options Display List
; -------------------------
;
DISPO .BYTE $70,$70,$70,$46
.WORD OPTMSG
.BYTE $07,$46
.WORD SB
.BYTE $46
.WORD OL1
.BYTE $06,$06,$46
.WORD SB
.BYTE $46
.WORD OL2
.BYTE $46
DOT .WORD TOPT
.BYTE $46
.WORD SB
.BYTE $46
.WORD OL3
.BYTE $46
DOD .WORD DOPT
.BYTE $46
.WORD SB
.BYTE $46
.WORD OL4
.BYTE $46
DOS .WORD SOPT
.BYTE $46
.WORD SB
.BYTE $46
.WORD OL5
.BYTE $46
DOC .WORD COPT
.BYTE $46
.WORD SB
.BYTE $46
.WORD OL6
.BYTE $46
DOU .WORD UOPT
.BYTE $46
.WORD SB
.BYTE $46
.WORD OPTMSG
.BYTE $41
.WORD DISPO
;
; Game Playfield Display List
; ---------------------------
;
DISPG .BYTE $70,$70,$70,$4F
.WORD DRAM
.DBYTE 15,15,15,15,15,15,15
.DBYTE 15,15,15,15,15,15,15
.DBYTE 15,15,15,15,15,15,15
.DBYTE 15,15,15,15,15,15,15
.DBYTE 15,15,15,15,15,15,15
.DBYTE 15,15,15,15,15,15,15
.DBYTE 15,15,15,15,15,15,15
.DBYTE 15,15,15,15,15,15,15
.DBYTE 15,15,15,15,15,15,15
.DBYTE 15,15,15,15,15,15,15
.DBYTE 15,15,15,15,15
.BYTE $70,$30,$47+DLI
.WORD TRAM
.BYTE $30,$42
.WORD ANALOG
.BYTE $41
.WORD DISPG
;
; Flying saucer in Intro Data
; ---------------------------
;
SAUCER .BYTE $18,$7E,$7E,$FF
.BYTE $FF,$7E,$7E,$18
WINDOW .BYTE $00,$00,$00,$55
.BYTE $55,$00,$00,$00
;
; Redefined Char Set Equates
; --------------------------
;
TMC = 1
AC = 3
CC = 4
DC = 5
EC = 6
FC = 7
GC = 8
HC = 9
IC = 10
LC = 11
NC = 12
PC = 13
RC = 14
TC = 15
WC = 16
YC = 17
CRC = 18
N0C = 19
BC = N0C+8
OC = N0C
SC = OC+5
SMK = N0C+10
SMK2 = SMK+8
SHC = SMK2+8
MT = SHC+2
UC = MT+1
COLC = UC+1
VC = COLC+1
MC = VC+1
KC = MC+1
BX = KC+$41
N7C = KC+2
;
; Introduction Title Data
; -----------------------
;
TITLE .BYTE 21,AC,NC,AC,LC
.BYTE OC,GC,$FF,36,MC
.BYTE AC,GC,AC,N0C+2,IC
.BYTE NC,EC,$FF,68
.BYTE +$40,PC,RC,EC,SC
.BYTE +$40,EC,NC,TC,SC
.BYTE $FF,97
.BYTE +$80,RC,AC,CC,EC,0
.BYTE +$80,IC,NC,0,SC,PC
.BYTE +$80,AC,CC,EC
.BYTE TMC,TMC+1,$FF,131
.BYTE +$40,WC,RC,IC,TC,TC,EC
.BYTE +$40,NC,0,BC,YC
.BYTE $FF,160
.BYTE +$C0,CC,HC,AC,RC,LC,EC
.BYTE +$C0,SC,0,0,BC,AC,CC
.BYTE +$C0,HC,AC,NC,DC
.BYTE $FF,197,CRC,0
.BYTE N0C+1,N0C+9,N0C+8
.BYTE N0C+4,$FF,230
.BYTE +$80,SHC,0,0,SHC
.BYTE $FF,246
.BYTE +$40,SHC+1,0,0,SHC+1
.BYTE $FF
;
; PRESS OPTION Message Data
; -------------------------
;
PMSG .BYTE 0,0,0,0,0,0,0,0,0
.BYTE +$C0,PC,RC,EC,SC,SC
.BYTE +$C0,0,OC,PC,TC,IC
.BYTE +$C0,OC,NC,0,0
.BYTE 0,0,0,0,0,0,0,0,0
;
; Options Screen Data
; -------------------
;
OPTMSG .BYTE BX,BX,BX,BX,BX,BX,BX,BX
.BYTE BX,BX,BX,BX,BX,BX,BX,BX
.BYTE BX,0,OC,PC,TC,IC,OC,NC
.BYTE SC
.BYTE +$C0,0,0,TC,COLC
TIMOPT .BYTE +$80,N0C+3,0
OL1 .BYTE BX,0
.BYTE +$40,OC,PC,TC,IC
.BYTE +$40,OC,NC,COLC,0
.BYTE +$80,LC,EC,FC,TC,0
.BYTE BX,BX,0
.BYTE +$40,SC,EC,LC,EC,CC
.BYTE +$40,TC,COLC
.BYTE +$C0,RC,IC,GC,HC,TC,0
.BYTE BX,BX,0
.BYTE +$40,SC,TC,AC,RC,TC
.BYTE +$40,COLC
.BYTE 0,0,PC,LC,AC,YC,0
OL2 .BYTE BX,0,TC,RC,IC,GC,GC,EC
.BYTE RC,COLC,0,0,0,0,0,BX
OL3 .BYTE BX,0
.BYTE +$80,DC,EC,NC,SC,IC,TC
.BYTE +$80,YC,COLC,0,0
.BYTE 0,0,0,BX
OL4 .BYTE BX,0
.BYTE +$80,SC,HC,IC,PC,SC
.BYTE +$80,COLC
.BYTE 0,0,0,0,0,0,0,BX
OL5 .BYTE BX,0
.BYTE +$80,CC,OC,MC,EC,TC
.BYTE +$80,SC,COLC
.BYTE 0,0,0,0,0,0,BX
OL6 .BYTE BX,0
.BYTE +$80,UC,NC,IC,VC
.BYTE +$80,EC,RC,SC,EC,COLC
.BYTE 0,0,0,0,BX
SB .BYTE BX,0,0,0,0,0,0,0
.BYTE 0,0,0,0,0,0,0
TOPT .BYTE BX,0,0,0,0
.BYTE +$C0,NC,OC,0,EC,FC,FC
.BYTE +$C0,EC,CC,TC,0
TOPT2 .BYTE BX,0,0,0,0,0,0
.BYTE +$C0,SC,HC,IC,EC
.BYTE +$C0,LC,DC,SC,0
TOPT3 .BYTE BX,0,0,0,0,0
.BYTE +$C0,MC,IC,SC,SC
.BYTE +$C0,IC,LC,EC,SC,0
TOPT4 .BYTE BX,0,0,0
.BYTE +$C0,WC,AC,RC,PC,0
.BYTE +$C0,DC,RC,IC,VC,EC,0
DOPT .BYTE BX,0,0,0,0,0
.BYTE +$C0,SC,TC,AC,NC
.BYTE +$C0,DC,AC,RC,DC,0
DOPT2 .BYTE BX,0,0,0,0,0,0,0
.BYTE +$C0,DC,OC,UC,BC,LC
.BYTE +$C0,EC,0
DOPT3 .BYTE BX,0,0,0,0,0,0,0
.BYTE +$C0,TC,RC,IC,PC,LC
.BYTE +$C0,EC,0
DOPT4 .BYTE BX,0,0,0,0,0,0,0,0
.BYTE +$C0,SC,UC,PC,EC,RC,0
SOPT .BYTE BX,0,0,0,0,0,0
.BYTE +$C0,RC,OC,CC,KC
.BYTE +$C0,EC,TC,SC,0
SOPT2 .BYTE BX,0,0,0,0,0,0
.BYTE +$C0,SC,AC,UC,CC,EC
.BYTE +$C0,RC,SC,0
COPT .BYTE BX,0,0,0,0,0
.BYTE +$C0,DC,IC,SC,AC
.BYTE +$C0,BC,LC,EC,DC,0
COPT2 .BYTE BX,0,0,0,0,0,0
.BYTE +$C0,EC,NC,AC,BC
.BYTE +$C0,LC,EC,DC,0
UOPT .BYTE BX,0,0,0,0,0
.BYTE +$C0,PC,OC,SC,IC
.BYTE +$C0,TC,IC,VC,EC,0
UOPT2 .BYTE BX,0,0,0,0,0
.BYTE +$C0,NC,EC,GC,AC,TC
.BYTE +$C0,IC,VC,EC
.BYTE 0,BX
ANALOG .BYTE 0,0,0,0,CC,OC,PC,YC
.BYTE RC,IC,GC,HC,TC,0
.BYTE CRC,0,AC,NC,AC,LC
.BYTE OC,GC,0,MC,AC,GC,AC
.BYTE N0C+2,IC,NC,EC,0,N0C+1
.BYTE N0C+9,N0C+8,N0C+4
.BYTE 0,0,0,0
TRAMI .BYTE 0,0,N0C,N0C,0,0,0
TRAMC .BYTE +$C0,N7C+3,COLC,N7C
.BYTE +$C0,N7C,SMK+7,N7C
.BYTE 0,0,0,N0C,N0C,0,0
TRAMN .BYTE 3,0,0,0,0
NUMMSK .BYTE $1F,$1E,$1A,$18
.BYTE $1D,$1B,$33,$35,$30
MISMSK .BYTE $FC,$F3
MISIMA .BYTE 3,0,3,1,1,1,1,3
.BYTE 0,3,2,3,2,2,3,2
MIMAGE .BYTE 0,0,0,0
MCMSK .BYTE $0E,$0D
LADR .WORD DOD,DOS,DOC,DOU,DOT
MADR .WORD TOPT,TOPT2,TOPT3,TOPT4
.WORD DOPT,DOPT2,DOPT3,DOPT4
.WORD SOPT,SOPT2,COPT
.WORD COPT2,UOPT,UOPT2
SELMSK .BYTE 3,3,1,1,1
SELMS2 .BYTE 0,4,4,2,2
SHIPS .BYTE 0,$18,$3C,$3C,$18
.BYTE $5A,$7E,$5A,$42
.BYTE 0,$18,$7E,$DB
.BYTE $7E,0,0,0,0,0
ROTMSK .BYTE $B6,$6D,$DB,$B6
VDMSK .BYTE $10,$20,$01,$02
XSTRT .BYTE 88,160
SCPNT .BYTE 3,17
SCNOTE .BYTE $50,$30
PCOLRS .BYTE $C4,$34
COMETM .BYTE 0,$3C,$7E,$7E
.BYTE $FF,$FF,$FF,$FF,$FF
.BYTE $FF,$7E,$7E,$3C,0
CE3K .BYTE $C6,$46,$F6,$66,$26
CE3KN .BYTE $6C,$A2,$51,$40,$48
;
; DLI Routine
; -----------
;
DLIVEC PHA ;save Acc
INC CLOCK ;increment clock
LDA RTCLOK ;system clock
ASL A ;times 2
AND #$CE ;mask color
STA PCOLR2 ;saucer color
PLA ;restore Acc
RTI ;return
;
; Console Checker
; ---------------
;
CONC LDA CONSOL ;get console
TAY ;to Y register
EOR CONSAV ;only different
AND CONSAV ;pressed keys
STY CONSAV ;save current
CMP #4 ;OPTION test
RTS ;return
;
; Beep Routine
; ------------
;
BUZZER STA AUDF2 ;buzzer freq
LDA #$A4 ;pure tone
STA AUDC2 ;in tone 2
LDY #$C0 ;beep counter
BZ DEX ;decrement X
BNE BZ ;zero yet? No.
STX ATRACT ;poke attract
DEY ;decrement Y
BNE BZ ;tone done? No.
STY AUDC2 ;Yes. turn off
RTS ;return
;
; Flying Saucer Routine
; ---------------------
;
DELAY LDX #0 ;get zero
LDA #$A4 ;pure tone
STA AUDC1 ;enable tone 1
STA AUDC2 ;enable tone 2
DL1 LDA #$12 ;1/5 sec count
DL2 CMP CLOCK ;compare clock
BNE DL2 ;match? No.
JSR CONC ;check console
BNE DL3 ;OPTION key? No.
PLA ;Yes. pull RTS
PLA ;addr from stack
JMP STOPTS ;options menu
DL3 LDA #0 ;get zero
STA CLOCK ;init clock
INX ;inc saucer pos
TXA ;move to Acc
STA HPOSP3 ;move saucer
AND #$FC ;window movement
STA HPOSP2 ;do windows
LSR A ;times 2
LSR A ;times 4
LSR A ;times 8
TAY ;index to displa
LDA PMSG,Y ;get text
STA DRAM+313,Y ;on screen
TXA ;saucer position
ASL A ;times 2
ASL A ;times 4
ASL A ;times 8
ASL A ;times 16
ASL A ;times 32 whew!
EOR #$F0 ;inverse hi bits
STA AUDF1 ;saucer sound
CLC ;clear carry
ADC #2 ;weird sound
STA AUDF2 ;with resonance
TXA ;saucer position
BNE DL1 ;off screen? No.
STA AUDC2 ;sound 2 off
STA VOLUME ;saucer volume
RTS ;return
;
; Move All P/M Off Screen
; -----------------------
;
CLRPM LDX #7 ;8 objects 0-7
LDA #0 ;zero position
CPM STA HPOSP0,X ;move P/M
DEX ;decrement count
BPL CPM ;done? No.
RTS ;return
;
; Turn Off All Sound
; ------------------
;
AUDOFF LDA #0 ;get zero
STA AUDC1 ;sound 1 off
STA AUDC2 ;sound 2 off
STA AUDC3 ;sound 3 off
STA AUDC4 ;sound 4 off
RTS ;return
;
; Program Execution Starts Here
; -----------------------------
;
RIS LDA #$3C ;cassette off
STA PACTL ;poke hardware
LDA # <DOT ;density lo
STA SELPNT ;select point lo
LDA # >DOT ;density hi
STA SELPNT+1 ;select pnt hi
LDA #0 ;init sound
STA AUDCTL ;audio control
LDX #YPLR+1-CONSAV
I1 STA CONSAV,X ;zero flags
DEX ;decrement index
BPL I1 ;done? No.
;
; System Reset Returns Here
; -------------------------
;
INTRO LDA #$29 ;value to enable
STA SDMCTL ;narrow playfld
LDA #3 ;value to turn
STA SKCTL ;off 2-tome mode
LDA # >MRAM ;high byte of
STA PMBASE ;P/M address
LDA #2 ;value to
STA GRACTL ;enable players
LDA # <DLIVEC ;DLI addr lo
STA VDSLST ;DLI vector lo
LDA # >DLIVEC ;DLI addr hi
STA VDSLST+1 ;DLI vector hi
LDA #$C0 ;value to
STA NMIEN ;enable DLI's
LDA # >CHARS ;addr of
STA CHBAS ;character set
LDA #$C6 ;value for
STA COLOR1 ;medium green
LDA #$94 ;value for
STA COLOR2 ;dark blue
LDA #$04 ;value for
STA PCOLR3 ;dark grey
LDA #1 ;value - player
STA SIZEP2 ;double width
STA SIZEP3 ;players set
STA GPRIOR ;PL has priority
JSR CLRPM ;remove PLayers
STA REVF ;rev screen flag
STA DIRSW ;sound direction
JSR AUDOFF ;sound off
TAX ;zero index
I2 STA DRAM,X ;clear display
STA DRAM+256,X ;page 2
STA DRAM+512,X ;page 3
STA MRAM+512,X ;player 2+3
DEX ;decrement index
BNE I2 ;done? No.
LDX #7 ;move 8 bytes
I3 LDA WINDOW,X ;saucer windows
STA MRAM+$0228,X ;player 2
LDA SAUCER,X ;saucer ship
STA MRAM+$02A8,X ;player 3
DEX ;decrement index
BPL I3 ;saucer done? No.
;
; Print Text Onto Display
; -----------------------
;
PTITL INX ;increment index
LDA TITLE,X ;get text
BEQ STITL ;byte zero? Yes.
TAY ;display index
P2 INX ;inc text index
LDA TITLE,X ;get text
CMP #$FF ;EOL flag
BEQ PTITL ;EOL? Yes.
STA DRAM+256,Y ;on screen
INY ;inc displa indx
JMP P2 ;continue
;
; Scroll Text For Intro
; ---------------------
;
STITL LDA # <DISPI ;DL addr lo
STA SDLSTL ;DL pntr lo
LDA # >DISPI ;DL addr hi
STA SDLSTL+1 ;DL pntr hi
LDA # >DRAM ;screen top hi
STA DADR+1 ;DL LMS hi
LDA #0 ;get zero
STA DADR ;DL LMS lo
STA ATRACT ;poke attract
STA VOLUME ;clear volume
S1 LDA #$10 ;16/60 sec count
S2 BIT CLOCK ;check clock
BEQ S2 ;time up? No.
JSR CONC ;console keys
BNE S2A ;OPTION key? No.
JMP STOPTS ;option menu
S2A LDA #0 ;get zero
STA CLOCK ;reset clock
INC SLINE ;inc scroll cnt
LDA SLINE ;scroll count
CLC ;clear carry
ADC DADR ;screen addr lo
EOR DIRSW ;sound direction
STA AUDF1 ;rocket sound
LDA SLINE ;scroll count
AND #7 ;use only 0..7
ADC #SMK+$C0 ;smoke offset
STA DRAM+518 ;put below both
STA DRAM+521 ;rocket ships
ADC #8 ;botm smk offset
STA DRAM+534 ;put below top
STA DRAM+537 ;smoke of ships
LDA SLINE ;scroll count
CMP #16 ;check overflow?
BNE S3 ;No. continue
LDA #0 ;get zero
STA SLINE ;reset count
STA VSCROL ;vertical scroll
INC VOLUME ;raise volume
LDA DIRSW ;sound direction
EOR VOLUME ;EOR with volume
ORA #$80 ;rough sounding
STA AUDC1 ;rocket sound
LDA DADR ;DL LMS lo
CLC ;clear carry
ADC #16 ;line width
STA DADR ;new DL LMS lo
BCC S3 ;overflow? No.
INC DADR+1 ;inc LMS hi
LDA #2+>DRAM ;cmp scrn end
CMP DADR+1 ;with LMS hi
BNE S4 ;at end? No.
JMP INTRO ;Yes. do intro
S4 JSR DELAY ;flying saucer
LDA #$20 ;value for
STA AUDF1 ;reset frequency
LDA #$8F ;full volume
STA AUDC1 ;reset tone
LDA #$0F ;reverse sound
STA DIRSW ;sound direction
S3 LDA SLINE ;scroll count
STA VSCROL ;vertical scroll
JMP S1 ;continue
;
; Game Option Menu Routine
; ------------------------
;
STOPTS LDA CLOCK ;allow one VBLANK
STP CMP CLOCK ;period to go by
BEQ STP ;before start
LDA #$21 ;value for
STA SDMCTL ;narrow playfld
LDA # <DISPO ;DL addr lo
STA SDLSTL ;displa list lo
LDA # >DISPO ;DL addr hi
STA SDLSTL+1 ;displa list hi
JSR SCRCLR ;clr inv Univ
JSR CLRPM ;clear players
STA ATRACT ;poke attract
STA GRACTL ;no players
JSR AUDOFF ;sound off
STA FLASHF ;clr flash flag
STA REVF ;clr inv flag
LDA #$94 ;color value for
STA COLOR2 ;medium blue
LDA #4 ;five notes 0-4
STA TEMP+3 ;same index
STS LDX TEMP+3 ;get index
LDA CE3K,X ;get color
STA COLOR1 ;change color
LDA CE3KN,X ;get note
JSR BUZZER ;play note
DEC TEMP+3 ;dec index
BPL STS ;done? No.
ST1 LDA CH ;check keyboard
AND #$3F ;mask CTRL/SHIFT
LDX #9 ;check for 0-9
ST1A CMP NUMMSK-1,X ;cmp keycode
BEQ ST1B ;numeric? Yes.
DEX ;decrement index
BNE ST1A ;done? No.
BEQ ST1C ;Yes. continue
ST1B TXA ;index is number
STA TRAMN ;store time
CLC ;clear carry
ADC #N0C+$80 ;display offset
STA TIMOPT ;show time opt
TXA ;number again
ADC #N7C+$C0 ;2nd char set
STA TRAMC ;game score line
LDA #$FF ;clear the
STA CH ;keyboard buffer
TXA ;number again
ASL A ;times 2
ASL A ;times 4
EOR #$3F ;inverse here to
JSR BUZZER ;number sound
ST1C JSR CONC ;check console
LSR A ;check START key
BCC ST2 ;START key? No.
JMP PLAYGM ;Yes. play game
;
; SELECT Key Handler
; ------------------
;
ST2 LSR A ;check SELECT
BCC ST3 ;SELECT key? No.
LDA #$30 ;Yes. do SELECT
JSR BUZZER ;key noise
LDX OPTION ;opt to change
INC TRIG,X ;inc option byte
LDA TRIG,X ;get option byte
AND SELMSK,X ;mask overflow
STA TRIG,X ;save opt byte
ORA SOFSET ;SELECT offset
ASL A ;times 2
TAX ;use as X index
LDY #0 ;zero Y index
LDA MADR,X ;text addr lo
STA (SELPNT),Y ;LMS byte lo
INY ;inc Y index
LDA MADR+1,X ;text addr hi
STA (SELPNT),Y ;LMS byte hi
JMP ST1 ;continue
;
; OPTION Key Handler
; ------------------
;
ST3 LSR A ;check OPTION
BCC ST1 ;OPTION key? No.
LDA #$10 ;Yes. do OPTION
JSR BUZZER ;key sound
LDX #1 ;reset text flag
ST4 STX OPTSW ;option switch
LDA OPTION ;option counter
ASL A ;times 2
ASL A ;times 4
ASL A ;times 8
ASL A ;times 16
TAX ;use as index
LDY #13 ;do 14 bytes
ST4A LDA #$80 ;get sign bit
EOR OL2+1,X ;flip sign
STA OL2+1,X ;save byte
INX ;increment index
DEY ;decrement count
BPL ST4A ;done? No.
LDA OPTSW ;option switch
BNE ST4B ;flipping done?
JMP ST1 ;Yes. continue
ST4B INC OPTION ;inc option cntr
LDA OPTION ;option counter
ASL A ;times 2
TAX ;use as index
LDA LADR-2,X ;DL LMS addr lo
STA SELPNT ;select pntr lo
LDA LADR-1,X ;DL LMS addr hi
STA SELPNT+1 ;select pntr hi
LDX OPTION ;option counter
LDA SELMS2,X ;offset table
ADC SOFSET ;present offset
STA SOFSET ;new offset
LDX #0 ;get zero
LDA OPTION ;option counter
CMP #5 ;range: 0..4
BNE ST4 ;overflow? No.
STX OPTION ;reset counter
STX SOFSET ;reset offset
JMP ST4 ;continue
;
; Asteroid Field Initializer
; --------------------------
; Initialize pointers
; -------------------
;
LDGRRT LDA # <ASTR ;asteroid right
STA GRPAGE ;field addr lo
TAY ;use as index
LDA # >ASTR ;asteroid right
STA GRPAGE+1 ;field addr hi
LDA #PAGES ;# of 256 byte
STA TEMP+2 ;blocks to move
RTS ;return
;
; Generate Asteroid Field Bytes
; -----------------------------
;
RANWRD LDA #2 ;# 4-bit nibbles
STA TEMP ;save counter
RANW0 CPX RANDOM ;with density
ROL TEMP+1 ;carry to bit 0
ASL TEMP+1 ;to bit 1
ASL TEMP+1 ;to bit 2
ASL TEMP+1 ;to bit 3
DEC TEMP ;nibble count
BNE RANW0 ;byte done? No.
LDA TEMP+1 ;move byte to
STA (GRPAGE),Y ;graphic area
RTS ;return
;
; Fill Workspace With Graphics
; ----------------------------
;
RANFIL JSR LDGRRT ;init pointers
ASL TEMP+2 ;blocks times 2
LDX DENS ;get density
RANF0 JSR RANWRD ;make starfield
INY ;inc block index
BNE RANF0 ;block done? No.
INC GRPAGE+1 ;inc page pntr
DEC TEMP+2 ;dec block cntr
BNE RANF0 ;done? No.
;
; Shift ASTR Space To Right
; -------------------------
;
DEC GRPAGE+1 ;dec page pntr
LDA #PAGES ;get block count
STA TEMP+2 ;store count
RANF1 DEY ;dec index
LDA (GRPAGE),Y ;asteroid byte
LSR A ;force to odd
STA (GRPAGE),Y ;replace byte
TYA ;exam index
BNE RANF1 ;index=0? No.
DEC GRPAGE+1 ;back up pntr
DEC TEMP+2 ;decrement count
BNE RANF1 ;Done? No.
RTS ;return
;
; Ship Scoring Routine
; --------------------
;
SCORE LDY #10 ;clr top 16 bytes
SC0 STA PM0,Y ;of player 0
STA PM1,Y ;and player 1
DEY ;decrement index
BPL SC0 ;done? No.
LDA XSTRT,X ;start position
STA XPLR,X ;to player pos
STA HPOSP0,X ;set hardware
SCOREM TXA ;save X to Acc
PHA ;push Acc
LDA SCPNT,X ;score Y pos
TAX ;use as index
INC TRAM,X ;increment score
LDA TRAM,X ;get score byte
CMP #N0C+10 ;value over 9?
BCC SC1 ;No. skip
LDA #N0C ;get zero char
STA TRAM,X ;to 1's position
INC TRAM-1,X ;inc 10's pos
SC1 PLA ;pull Acc
TAX ;get X indx back
LDA SCNOTE,X ;score sound
STA AUDF3 ;set frequency
LDA #$AE ;loud sound
STA AUDC3 ;set volume
LDA #3 ;value for
STA SCLOCK ;sound duration
DEC SCORES,X ;dec max score
BNE SC2 ;from 99 to zero
LDA #0 ;99 points so
STA ENDGAM ;end the game
SC2 LDA #$FF ;value to return
STA HITCLR ;clear collision
RTS ;return
;
; Ship Graphics Rotation
; ----------------------
;
ROTOR TXA ;move X to Acc
PHA ;save X
LDA CLOCK ;get clock
ROR A ;test bit 0
BCS RT2 ;bit=1? Yes.
DEC ROTATE ;rotation index
BPL RT1 ;rotate<0? No.
LDA #2 ;reset value for
STA ROTATE ;rotation index
RT1 LDX ROTATE ;get index
LDA ROTMSK,X ;spinner graphic
STA SHIPS+12 ;saucer section
AND #$3C ;mask for rocket
STA SHIPS+2 ;rocket upper