; INCLUDE 2600.A65
VSync EQU $00
VBlank EQU $01
WSync EQU $02
RSync EQU $03
NuSiz0 EQU $04
NuSiz1 EQU $05
CoLuP0 EQU $06
CoLuP1 EQU $07
CoLuPf EQU $08
CoLuBk EQU $09
CtrlPf EQU $0A
RefP0 EQU $0B
RefP1 EQU $0C
Pf0 EQU $0D
Pf1 EQU $0E
Pf2 EQU $0F
ResP0 EQU $10
ResP1 EQU $11
ResM0 EQU $12
ResM1 EQU $13
ResBl EQU $14
AudC0 EQU $15
AudC1 EQU $16
AudF0 EQU $17
AudF1 EQU $18
AudV0 EQU $19
AudV1 EQU $1A
GrP0 EQU $1B
GrP1 EQU $1C
EnaM0 EQU $1D
EnaM1 EQU $1E
EnaBl EQU $1F
HMP0 EQU $20
HMP1 EQU $21
HMM0 EQU $22
HMM1 EQU $23
HMBl EQU $24
VDelP0 EQU $25
VDelP1 EQU $26
VDelBl EQU $27
ResMP0 EQU $28
ResMP1 EQU $29
HMove EQU $2A
HMClr EQU $2B
CxClr EQU $2C
CxM0P EQU $00
CxM1P EQU $01
CxP0FB EQU $02
CxP1FB EQU $03
CxM0FB EQU $04
CxM1FB EQU $05
CxBlPf EQU $06
CxPPMM EQU $07
Inpt0 EQU $08
Inpt1 EQU $09
Inpt2 EQU $0A
Inpt3 EQU $0B
Inpt4 EQU $0C
Inpt5 EQU $0D
SwchA EQU $280
SwACnt EQU $281
SwchB EQU $282
SwBCnt EQU $283
InTim EQU $284
Tim1T EQU $294
Tim8T EQU $295
Tim64T EQU $296
T1024T EQU $297
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
ORG $80
Temp0 DS 1
Temp1 DS 1
Temp2 DS 1
Temp3 DS 1
Temp4 DS 1
MaxScr EQU $20
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
ORG $1000
Start: SEI ; Initialize the machine, set interrupt disable
CLD ; clear decimal mode
LDX #$FF ; start X at $FF (255d)
TXS ; transfer it to the stack
INX ; set X to $00
TXA ; transfer it to the accumulator, A
@1 STA 0,X ; store $00 at 0+X
INX ; increment X
BNE @1 ; if X is not zero yet, go back to @1
; the above loop zeros out $00 to $FF
; at this point X is $00
LDA #$15 ;
STA Temp1 ;
LDA #$00 ;
STA Temp0 ; this sets up reference to Table
LDA #$05 ; number of screens per frame
STA Temp2 ;
LDA #$30 ; number of frames facing initial direction
STA Temp4 ; store it
LDA #$08 ; initial direction
STA Temp3
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
Top: ; Start a new screen
LDA #$05
STA Tim64T ; set timer for $05*$40 = $140 (320d) clocks
; do overscan stuff here
LDA #$00 ; put $00 in A
STA Pf0 ; clear out first playfield section
STA Pf1 ; clear out second playfield section
STA Pf2 ; clear out third playfield section
STA GrP0 ; clear out player graphic 0
STA GrP1 ; clear out player graphic 1
STA EnaM0 ; clear out missile 0
STA EnaM1 ; clear out missile 1
STA EnaBl ; clear out ball
STA CoLuP0 ; set player 0 to black
STA CoLuP1 ; set player 1 to black
STA CoLuPf ; set playfield to black
STA CoLuBk ; set background to black
; wait for overscan to finish, then start blanking
@1 LDA InTim ; find current value of timer
BNE @1 ; if timer not zero, wait
; when we get here, A will be $00
LDY #$02 ; this is 10000010b
STY WSync ; wait for end of current line
STY VBlank ; start vertical, disable latches, dump orts
; this is from the 10000010b
STY VSync ; start vertical sync
STY WSync ; send three lines while doing vertical sync
STY WSync ;
STY WSync ;
STA VSync ; end vertical sync
LDA #$05 ; put $05 in A
STA Tim64T ; start vblank timer
; Setup the playfield graphics
LDA #$06 ; color grey
STA CoLuP0 ; make robot grey
LDA #$0E ; color white
STA CoLuBk ; make the background white
JSR Blank ; do blanking stuff
STA WSync ; one more line for good measure
; Draw the screen
LDA Temp4 ; get frames facing current direction
CMP #$30 ; is it $30?
BNE DontTurn; if not, don't turn him
LDA Temp3 ; get current direction
EOR #$FF ; NOT that value
STA Temp3 ; store new direction
STA RefP0 ; make player face other direction
LDA #$00 ; make A $00
STA Temp4 ; new numer of frames
DontTurn
LDX #$20 ; get ready to do $20 (32d) blank lines
Loop1 STA WSync ; do one blank line
DEX ; decrement counter X
BNE Loop1 ; if X not $00 then do another line
STA WSync ; start at end of WSync so we know where to put
; player graphic
LDX #$05 ; prepare to position player graphic 0
Waitin DEX ; killin' time
BNE Waitin ; keep on killin' time
STA ResP0 ; start player 0 at this point in screen
STA WSync ; now next line
LDY #$00 ; start at line 0 of current frame
Draw LDA (Temp0),Y
; indirect call to memory
; Y holds frame number of line and Temp1 and
; the following byte hold address that current
; frame data starts at
STA GrP0 ; store this line of data in player graphic 0 register
CPY #$09 ; are we on $09th line?
BNE Onward ; if not go on to next line
LDA #$00 ; set A to $00
STA CoLuP0 ; and set player graphic 0 color to black
Onward STA WSync ; done with this line
INY ; go to next line of graphics data
CPY #$0E ; done with this frame?
BNE Draw ; if not done, do another line
; note that last line of data effective cuts off
; player graphic 0 since it is a "clear" line
LDX #$9E ; do rest of screen, $9E (154d) lines approx.
Loop2 STA WSync ; do a line
DEX ; count down
BNE Loop2 ; if not at zero, do another line
DEC Temp2 ; decrement number of screens on this frame
BNE NextScr ; if not zero, go to next screen
LDA #$05 ; set up to do 5 more frames
STA Temp2 ; and store it
; now get new frame info
LDA Temp0 ; get current frame address
ADC #$0D ; add 14 lines to its address
CMP #$38 ; have we reached end of Table?
BNE StoreFr ; if not, store new frame's address
LDA #$00 ; if so, start over with first frame
StoreFr STA Temp0 ;
NextScr DEC Temp4 ; decrement number of frames remaining facing this
; direction
JMP Top ; done with this frame, go back to Top
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
ORG $1500 ; start table at $1500
Table: DW $7838 ; 00111000
; 01111000
DW $1878 ; 01111000
; 00011000
DW $FF7E ; 01111110
; 11111111
DW $99BD ; 10111101
; 10011001
DW $7618 ; 00011000
; 01110110
DW $9429 ; 00101001
; 10010100
DW $006E ; 01101110
; 00000000
DW $7838 ; 00111000
; 01111000
DW $1878 ; 01111000
; 00011000
DW $FF7E ; 01111110
; 11111111
DW $99BD ; 10111101
; 10011001
DW $3A18 ; 00011000
; 00111010
DW $95A9 ; 10101001
; 10010101
DW $005C ; 01011100
; 00000000
DW $7838 ; 00111000
; 01111000
DW $1878 ; 01111000
; 00011000
DW $FF7E ; 01111110
; 11111111
DW $99BD ; 10111101
; 10011001
DW $5C18 ; 00011000
; 01011100
DW $95A9 ; 10101001
; 10010101
DW $003A ; 00111010
; 00000000
DW $7838 ; 00111000
; 01111000
DW $1878 ; 01111000
; 00011000
DW $FF7E ; 01111110
; 11111111
DW $99BD ; 10111101
; 10011001
DW $6E18 ; 00011000
; 01101110
DW $15A8 ; 10101000
; 00010101
DW $0076 ; 01110110
; 00000000
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
Blank: NOP ; spacer
@1 LDA InTim ; find out current status of timer
BNE @1 ; if timer is zero, then done, otherwise check timer
STA WSync ; A is $00, kick out another line
STA VBlank ; blank off, disable latches, remove dump
RTS
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
ORG $17FC ; vectors for 2k cart
DW Start ; reset
DW Start ; IRQ
ORG $1FFC ; vectors for 4k cart
DW Start ; reset
DW Start ; IRQ
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
END
