**************************
*                        *
*        SPEEDSKI        *
*                        *
*   By Bill Richardson   *
*                        *
*   Copyright (c) 1985   *
*    ANALOG Computing    *
*                        *
**************************
;
;OS EQUATES
;----------
;
HPOSP0 = $D000  ;Plr0 horiz pos
HPOSP1 = $D001  ;Plr1 horiz pos
P0PF =  $D004   ;Plr0 collision
GRACTL = $D01D  ;Graphics ctrl
HITCLR = $D01E  ;Collision reg
CONSOL = $D01F  ;Consol keys
AUDF1 = $D200   ;Audio Freq 1
AUDC1 = $D201   ;Audio Ctrl 1
AUDF2 = $D202   ;Audio Freq 2
AUDC2 = $D203   ;Audio Ctrl 2
AUDCTL = $D208  ;Main audio ctrl
SKCTL = $D20F   ;Serial ctrl
VSCROL = $D405  ;Vert Scroll reg
PMBASE = $D407  ;P/M base addr
SETVBV = $E45C  ;Set VBLANK
SYSVBV = $E45F  ;Exit VBLANK
;
;PAGE ZERO
;---------
;
    Org  $80
;
CLOCK DB 1,1,1,1,1,1,1     ;Special clock
SCROLLED DB 1  ;# lines scrolled
SCROLFLG DB 1  ;Scroll done flag
SPEED DB 1   ;Scrolling speed
XPOS DB 1      ;Skier's horz pos
YPOS DB 1     ;Skier's vert pos
IMAGEPTR DB 1,1  ;Image pntr
TIMES DB 1   ;Course scrl cnt
TIMESFLG DB 1  ;End course flg
VOLUME DB 1   ;Volume of sounds
;
;SHADOW REGISTERS, ETC.
;----------------------
;
ATRACT = 77     ;Attract mode flg
SAVMSC = 88     ;Scrn memory pntr
SDMCTL = $022F  ;DMA enable
SDLSTL = $0230  ;Disp List pntr
GPRIOR = $026F  ;Priority reg
STICK0 = $0278  ;Joystick 0
STRIG0 = $0284  ;Stick trigger 0
PCOLR0 = $02C0  ;Player 0 color
PCOLR1 = $02C1  ;Player 1 color
COLOR0 = $02C4  ;Playfld Color 0
CHBAS = $02F4   ;CH Base addr
CH  =   $02FC   ;Last Key pressed
;
    Org  $3000
;
SCRN1 Org *+480   ;1st screen
SCRN2 Org *+480   ;2nd screen
SCRN3 Org *+480   ;3rd screen
SCRN4 Org *+480   ;4th screen
SCRN5 Org *+480   ;5th screen
SCRN6 Org *+240   ;6th screen
SCRLFIN Org *+240 ;End scrl adr
;
    Org  $0400
;
PMSTART Org *+$0200 ;P/M area
PLR0 Org *+$80    ;Player0
PLR1 Org *+$80    ;Player1
;
;CHARACTER SET
;-------------
;
    Org  $2000
;
CHSET .BYTE 0,0,0,0,0,0,0,0,128,128
    .BYTE 128,170,130,170,0,170
    .BYTE 0,0,0,8,8,10,0,170
    .BYTE 0,0,0,32,32,160,32,160
    .BYTE 21,16,16,21,16,16,21,0
    .BYTE 65,17,17,80,16,16,64,0
    .BYTE 80,16,80,0,64,64,64,0
    .BYTE 64,64,64,64,64,64,64,0
    .BYTE 64,64,64,64,64,64,64,0
    .BYTE 0,84,65,65,85,68,65,65
    .BYTE 0,16,0,17,17,17,17,17
    .BYTE 0,0,0,81,17,81,17,81
    .BYTE 0,1,1,81,1,1,1,81
    .BYTE 0,0,0,81,16,17,17,17
    .BYTE 0,0,24,24,0,24,24,0,0,0
    .BYTE 0,0,0,24,24,0,126,103
    .BYTE 103,103,103,103,127,63
    .BYTE 28,60,124,28,28,28,127
    .BYTE 127,126,103,7,127,112
    .BYTE 115,115,127,126,103,7
    .BYTE 63,7,103,127,63,6,15,27
    .BYTE 51,127,127,7,15,126,96
    .BYTE 126,103,7,103,127,63
    .BYTE 126,103,96,126,103,103
    .BYTE 127,63,126,103,7,14,28
    .BYTE 28,28,28,126,103,103
    .BYTE 127,103,103,127,63,126
    .BYTE 103,103,127,7,103,127
    .BYTE 63,0,0,0,0,0,0,0,1
    .BYTE 1,1,5,21,21,85,85,85
    .BYTE 0,64,64,80,64,80,84,84
    .BYTE 0,0,0,1,5,1,0,0
    .BYTE 5,21,21,85,85,85,0,0
    .BYTE 85,85,85,85,85,85,63,63
    .BYTE 85,85,85,85,85,85,0,0
    .BYTE 0,0,64,80,84,85,0,0
    .BYTE 0,0,15,60,0,252,15,0
    .BYTE 192,192,192,252,204,207
    .BYTE 192,207,0,0,0,0,0,192,0
    .BYTE 192,0,0,15,60,48,0,0,0
    .BYTE 252,207,195,192,192,192
    .BYTE 192,192,0,0,192,0,0,0,0
    .BYTE 0,0,0,0,0,0,0,0,2,0,0,2
    .BYTE 2,10,42,170,170,32,168
    .BYTE 168,170,170,170,170,170
    .BYTE 0,0,0,0,0,128,160,160
    .BYTE 0,0,0,0,0,2,0,0,2,10,10
    .BYTE 42,170,170,0,0,170,170
    .BYTE 170,170,170,170,3,3,170
    .BYTE 170,170,170,170,170,252
    .BYTE 252,168,170,170,170,170
    .BYTE 170,0,0,0,0,128,160,168
    .BYTE 170,0,0,0,0,0,0,0,0,1,5
    .BYTE 0,0,1,5,21,85,85,85
    .BYTE 20,85,85,85,85,85,85,85
    .BYTE 0,0,80,84,85,85,85,85
    .BYTE 0,0,0,0,0,80,84,85
    .BYTE 0,0,1,5,0,0,0,0
    .BYTE 21,85,85,85,0,0,0,0,85
    .BYTE 85,85,85,0,0,0,0,85,85
    .BYTE 85,85,255,255,255,255
    .BYTE 85,85,85,85,192,192,192
    .BYTE 192,85,85,85,85,0,0,0,0
    .BYTE 64,80,84,85,0,0,0,0
    .BYTE 0,0,0,64,0,0,0,0,2,10
    .BYTE 10,10,42,42,42,42,0,128
    .BYTE 160,160,160,168,168,168
    .BYTE 0,2,2,2,0,0,0,0,170,170
    .BYTE 170,170,170,3,3,3,168
    .BYTE 170,170,170,170,192,192
    .BYTE 192,0,0,0,0,128,0,0,0
    .BYTE 1,5,5,5,21,21,21,21
    .BYTE 0,64,80,80,80,84,84,84
    .BYTE 0,1,1,1,0,0,0,0,85,85
    .BYTE 85,85,85,3,3,3,84,85,85
    .BYTE 85,85,192,192,192
    .BYTE 0,0,0,0,64,0,0,0
    .BYTE 0,0,0,252,15,0,63,0,48
    .BYTE 48,60,60,255,63,252,63
    .BYTE 0,0,0,240,0,252,0,240
    .BYTE 240,60,15,0,0,0,0,0,60
    .BYTE 60,255,60,63,60,60,60
    .BYTE 12,192,192,0,0,0,0,0
    .BYTE 0,0,0,0,192,240,255,255
    .BYTE 0,0,0,0,0,0,0,192
    .BYTE 0,0,0,0,0,0,0,0
    .BYTE 0,0,0,0,0,0,0,3,0,0,0
    .BYTE 0,3,15,255,255,192,192
    .BYTE 192,192,192,192,192,192
    .BYTE 3,3,3,3,3,3,3,3,42,37
    .BYTE 38,38,38,38,37,42,170
    .BYTE 85,170,0,0,170,85,170
    .BYTE 160,96,160,0,0,160,96
    .BYTE 96,0,0,0,0,0,170,149
    .BYTE 154,0,0,0,0,0,168,88
    .BYTE 152,0,0,0,0,0,170,149
    .BYTE 154,0,0,0,0,0,138,137
    .BYTE 137,0,0,0,0,0,168,88
    .BYTE 168,0,0,0,0,0,42,37,42
    .BYTE 2,2,2,2,2,170,85,170,96
    .BYTE 96,96,96,96,96,96,160
    .BYTE 152,154,149,154,152,152
    .BYTE 152,168,152,152,88,168
    .BYTE 0,0,0,0,152,154,150,154
    .BYTE 152,154,149,170,9,9,9,9
    .BYTE 9,137,137,138,128,160
    .BYTE 96,160,128,168,88,168
    .BYTE 0,0,0,0,0,170,149,154
    .BYTE 0,0,0,0,0,128,160,104
    .BYTE 42,37,38,38,38,38,37,42
    .BYTE 170,85,170,0,0,170,85
    .BYTE 170,160,96,160,0,0,162
    .BYTE 98,98,0,0,0,0,0,162,98
    .BYTE 98,0,0,0,0,0,162,98,98
    .BYTE 0,0,0,0,0,170,86,154
    .BYTE 154,152,152,152,154,154
    .BYTE 149,170,152,152,152,152
    .BYTE 152,104,160,128,0,0,0,0
    .BYTE 0,42,37,42,2,2,2,2,2
    .BYTE 170,85,170,98,98,98,98
    .BYTE 98,98,98,162,105,102,90
    .BYTE 102,105,106,98,162,160
    .BYTE 128,0,128,160,98,98,162
    .BYTE 152,152,152,152,152,154
    .BYTE 86,170,0,0,0,17,65,1,1
    .BYTE 1,0,16,16,81,17,17,16
    .BYTE 81,0,0,0,84,0,84,4,84
    .BYTE 0,0,0,84,68,68,68,84
    .BYTE 0,0,0,64,84,68,68,68
    .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
;
;MESSAGES
;--------
;
GAMELOGO .BYTE 88,89,90,91,92,93,94,95
    .BYTE 104,105,106,107,108,109
    .BYTE 110,111,96,97,98,99,100
    .BYTE 101,102,103,112,113,114
    .BYTE 115,116,117,118,119
MYNAME .BYTE 1,2,3,0,4,5,6,7,8,0,9
    .BYTE 10,12,13,11,120,121,122
    .BYTE 123,124
;
;DISPLAY LIST
;------------
;
DLIST .BYTE $70,$70,$44
    .WORD $00
    .BYTE $04,$00,$04,$65
    .WORD $4000
    .BYTE $25,$25,$25,$25
    .BYTE $25,$25,$25,$25
    .BYTE $25,$25,$05,$41
    .WORD DLIST
;
;P/M SHAPES
;----------
;
IM1 .BYTE 12,0,24,0,24,24
    .BYTE 60,0,124,0,48,136
    .BYTE 56,68,36,2,72,0
    .BYTE 72,34,0,68,0,136
IM2 .BYTE 0,0,12,0,24,0
    .BYTE 24,24,60,0,24,36
    .BYTE 60,66,60,0,36,0
    .BYTE 36,0,0,36,0,36
IM3 .BYTE 48,0,24,0,24,24
    .BYTE 60,0,62,0,12,17
    .BYTE 28,34,36,64,18,0
    .BYTE 18,68,0,34,0,17
IM4 .BYTE 4,0,25,2,25,28
    .BYTE 254,0,185,0,120,128
    .BYTE 56,128,40,0,64,20
    .BYTE 76,34,65,0,0,0
IM5 .BYTE 16,0,24,0,128,96
    .BYTE 88,24,58,4,45,2
    .BYTE 28,0,26,0,34,0
    .BYTE 66,129,0,66,0,4
;
;Initial screen colors
;---------------------
;
COLTBL .BYTE 184,180,20,52,14
;
;Copy screens
;------------
;
PRGSTART LDX #0
COPY1 LDA SCRNBASE,X
    STA SCRN1,X
    STA SCRN4,X
    LDA SCRNBASE+480,X
    STA SCRN2,X
    STA SCRN5,X
    LDA SCRNBASE+960,X
    STA SCRN3,X
    STA SCRN6,X
    INX
    BNE COPY1
COPY2 LDA SCRNBASE+256,X
    STA SCRN1+256,X
    STA SCRN4+256,X
    LDA SCRNBASE+736,X
    STA SCRN2+256,X
    STA SCRN5+256,X
    LDA SCRNBASE+1216,X
    STA SCRN3+256,X
    STA SCRN6+256,X
    INX
    CPX #224
    BNE COPY2
    LDA #0
    TAX
CLEAR1 STA SCRN6+480,X ;Clr bottom
    INX         ;of scrolling
    BNE CLEAR1  ;screen memory
    LDA SAVMSC
    STA DLIST+3 ;Set DLIST
    LDA SAVMSC+1 ;pointer to
    STA DLIST+4 ;screen memory
    LDA #0      ;Clear
    LDY #120    ;top
CLEARSCR STA (SAVMSC),Y ;of
    DEY         ;screen
    BPL CLEARSCR
    LDX #4
COLORSCR LDA COLTBL,X ;color tbl
    STA COLOR0,X
    DEX
    BPL COLORSCR
    LDA # <DLIST ;Tell ANTIC
    STA SDLSTL  ;where to
    LDA # >DLIST ;find custom
    STA SDLSTL+1 ;Display List
    LDY #27     ;This routine
    LDX #15     ;puts the top 16
I1  LDA GAMELOGO,X ;characters of
    STA (SAVMSC),Y ;"SPEEDSKI"
    DEY         ;logo on the
    DEX         ;screen
    BPL I1
    LDY #67     ;Puts
    LDX #31     ;the last
I2  LDA GAMELOGO,X
    STA (SAVMSC),Y ;16 characters
    DEY         ;of logo on
    DEX         ;the screen
    CPX #15
    BNE I2
    LDA # >CHSET ;Give computer
    STA CHBAS   ;adr of new CHSET
    LDA #0      ;Initialize
    STA AUDCTL  ;POKEY
    LDA #3      ;sound
    STA SKCTL   ;chip
    LDA #2      ;Enable
    STA GRACTL  ;P/M graphics
    LDA # >PMSTART ;Tell where PM
    STA PMBASE  ;graphics are
    JSR ERASE   ;Clear P/M memory
    LDA #40     ;Multi-color plrs
    STA GPRIOR  ;Set P/M priority
    LDA #152    ;light blue
    STA PCOLR0
    LDA #118    ;blue
    STA PCOLR1
    LDA #46     ;Double line
    STA SDMCTL  ;resolution plrs
    LDY #110
    LDX #19     ;This routine
I3  LDA MYNAME,X ;puts the
    STA (SAVMSC),Y ;author's name
    DEY         ;on the 3rd line
    DEX         ;of the screen
    BPL I3
;
;EVERY TIME INITIALIZATION
;-------------------------
;
INIT LDA # <SCRN1 ;Point DLIST
    STA DLIST+9 ;to scrolling
    LDA # >SCRN1 ;screen
    STA DLIST+10
    LDA #0      ;Reset # scan
    STA SCROLLED ;lines scrolled
    STA TIMESFLG ;and TIMESFLG
    STA TIMES   ;+ course scroll
    STA SCROLFLG ;Do scrolling
    LDA #1      ;Set scroll speed
    STA SPEED   ;to slow
    LDA #0      ;Set
    LDX #6      ;clock
I4  STA CLOCK,X ;to
    DEX         ;0:00.00
    BPL I4
    STX CLOCK+2 ;"." character
    STX CH      ;Reset last key
    DEX
    STX CLOCK+5 ;":" character
    LDA #120    ;Set horizontal
    STA XPOS    ;pos of skier
    LDA #36     ;Set vertical
    STA YPOS    ;pos of skier
;
;BEGIN GAME
;----------
;
WAITLOOP LDA CONSOL
    ROR A       ;START Pressed?
    BCC LETSGO  ;Yes! start game
    LDA STRIG0  ;Trigger pressed?
    BNE WAITLOOP ;No, wait
LETSGO JSR CLEAR3RD ;Clr 3rd line
    LDA #6      ;Chg ANTIC 4 line
    STA DLIST+7 ;to GR.1 line
    STA ATRACT  ;Reset Attract
    JSR SCROLLIT ;Start VBLANK
;
;INTRODUCTION
;------------
;
    LDA XPOS    ;Position the
    STA HPOSP0  ;skier
    STA HPOSP1  ;horizontally
INTRO JSR ERASE ;Erase skier
    LDA # <IM2  ;Tell IMAGEPTR
    STA IMAGEPTR ;which image
    LDA # >IM2  ;to
    STA IMAGEPTR+1 ;draw
    JSR DRAW    ;Go draw skiers
    INC YPOS    ;Move down screen
    LDA YPOS    ;See if skier has
    CMP #72     ;reached middle
    BEQ MAINLOOP ;of screen? Yes.
    LDA YPOS    ;Vert position
    LSR A       ;/2
    LSR A       ;/4
    LSR A       ;/8
    STA AUDF1   ;Set frequency,
    STA AUDC1   ;vol, distortion
    LDX #10     ;HI byte and LO
    LDY #0      ;byte of delay
    JSR DELAY   ;Slow down action
    JMP INTRO   ;Do it again
;
;THE MAIN LOOP
;-------------
;
MAINLOOP STA HITCLR ;Clr Collision
    LDA STICK0  ;Read joystick
    CMP #5      ;Down and right?
    BEQ MP2A    ;Go draw skier
    CMP #6      ;Up and right?
    BEQ MP2
    CMP #7
    BNE MP3
MP2 DEC SPEED
MP2A JMP RIGHT
;
MP3 CMP #9      ;Down and left?
    BEQ MP5A
    CMP #10     ;Up and left?
    BEQ MP5
    CMP #11     ;Left?
    BNE MP6
MP5 DEC SPEED
MP5A JMP LEFT
;
MP6 CMP #13     ;Down?
    BNE MP7
    INC SPEED
    JMP STRAIGHT
;
MP7 CMP #14     ;Up?
    BNE MP8
    DEC SPEED
    JSR TESTSPD
    DEC SPEED
MP8 JMP STRAIGHT
;
CONTINUE LDA XPOS ;Horizontal pos
    STA HPOSP0  ;Position Plr0
    STA HPOSP1  ;Position Plr1
    LDA CH      ;Last key pressed
    CMP #255
    BEQ MP9     ;No key pressed
    JSR PAUSE   ;Activate pause
MP9 LDA CONSOL
    CMP #6      ;START pressed?
    BNE MP10    ;No.
    JMP INIT    ;Start over
;
MP10 LDA P0PF   ;Check collision
    BEQ MP11    ;Nobody crashed
    JSR CRASH   ;Crash occured
MP11 LDX #12
    LDY #0
    JSR DELAY   ;Slow the action
    LDA SCROLFLG ;scrolling?
    BEQ MP12    ;Yes. continue
    JMP ENDGAME
;
MP12 JSR TESTX  ;Skier's X coord
    JMP MAINLOOP ;Loop back
;
;Delay subroutine
;----------------
;
DELAY DEY
    BNE DELAY
    DEX
    BNE DELAY
    RTS
;
;Erase players 0 & 1
;-------------------
;
ERASE LDA #0
    TAX
MP13 STA PLR0,X ;Erase Plr0
    STA PLR1,X  ;Erase Plr1
    DEX
    BNE MP13
    RTS
;
;Start scrolling & clock
;-----------------------
;
SCROLLIT LDX # >VBI
    LDY # <VBI
    BNE HALT2
;
;Disable VBLANK
;--------------
;
HALT LDX # >SYSVBV
    LDY # <SYSVBV
HALT2 LDA #6
    JMP SETVBV
;
;Subroutine to draw players
;--------------------------
;
DRAW LDX YPOS   ;Get vert pos
    LDY #23     ;# bytes to draw
DRAWLOOP LDA (IMAGEPTR),Y ;Get number
    STA PLR1,X  ;Put it in Plr1
    DEY
    LDA (IMAGEPTR),Y ;Get another
    STA PLR0,X  ;Put it in Plr0
    DEX
    DEY
    BPL DRAWLOOP ;Do until Y=255
    RTS
;
;Set skier to right
;------------------
;
RIGHT JSR TESTSPD
    INC XPOS
    LDA # <IM3  ;Point to
    STA IMAGEPTR ;right
    LDA # >IM3  ;skier
    STA IMAGEPTR+1
    LDA #6
    BNE LEFT1
;
;Set skier to left
;-----------------
;
LEFT JSR TESTSPD
    DEC XPOS
    LDA # <IM1  ;Point to
    STA IMAGEPTR ;left
    LDA # >IM1  ;skier
    STA IMAGEPTR+1
    LDA #4
LEFT1 STA AUDF1
    LDA #12
LEFT2 STA AUDC1
    JSR DRAW
    JMP CONTINUE
;
;Set skier to straight
;---------------------
;
STRAIGHT JSR TESTSPD
    LDA # <IM2  ;Point to
    STA IMAGEPTR ;straight
    LDA # >IM2  ;skier
    STA IMAGEPTR+1
    LDA #2
    STA AUDF1
    LDA #8
    BNE LEFT2
;
;Test scrolling speed
;--------------------
;
TESTSPD LDA SPEED
    CMP #65     ;Is it > maximum?
    BNE MP14    ;No
    DEC SPEED   ;Make maximum
    RTS
MP14 LDA SPEED  ;Speed < minimum?
    BNE MP15    ;No.
    INC SPEED   ;Make minimum
MP15 RTS
;
;Pause subroutine
;----------------
;
PAUSE JSR HALT  ;Stop scrolling
    LDA #255    ;Reset last
    STA CH      ;key pressed
MP16 LDA CONSOL ;Wait for OPTION
    CMP #3      ;to be
    BNE MP16    ;pressed
    JMP SCROLLIT
;
;Gameover
;--------
;
ENDGAME JSR HALT ;Stop scrolling
    LDA #121    ;note C
    STA AUDF1
    LDA #166    ;with pure tone
    STA AUDC1   ;and some volume
    LDX #0      ;hold the tone
    LDY #0      ;for a while
    JSR DELAY
    LDA #96     ;note E
    STA AUDF1
    LDA #121    ;note C
    STA AUDF2
    LDA #170    ;with pure tone
    STA AUDC1   ;and more volume
    STA AUDC2
    LDX #128    ;Hold tone half
    JSR DELAY   ;as long
    LDA #81     ;note G
    STA AUDF1
    LDA #96     ;note E
    STA AUDF2
    LDA #172    ;more volume
    STA AUDC1
    STA AUDC2
    LDX #192    ;Hold tone
    JSR DELAY
    LDA #60     ;note C
    STA AUDF1
    LDA #81     ;note G
    STA AUDF2
    LDA #174    ;more volume
    STA AUDC1
    STA AUDC2
    JSR DELAY   ;Hold note twice
    JSR DELAY   ;as long as 1st
    LDA #0
    STA AUDC1   ;Turn off
    STA AUDC2   ;sound
MP17 LDA CONSOL ;See if START
    ROR A       ;pressed
    BCC MP18
    LDA STRIG0  ;If trig pressed
    BNE MP17    ;start game over
MP18 JMP INIT
;
;Crash!
;------
;
CRASH LDA #1    ;Stop
    STA SCROLFLG ;scrolling
    LDA #15     ;Set volume
    STA VOLUME  ;to loud
MP19 LDA #255
    STA AUDF1
    SBC VOLUME  ;255-VOLUME
    STA AUDF2   ;for Freq 2
    LDA VOLUME  ;dist 0+VOLUME
    STA AUDC1   ;for Ctrl 1
    ADC #192    ;Dist 12+VOLUME
    STA AUDC2   ;for Ctrl 2
    DEC VOLUME  ;Reduce volumn
    LDX #20
    JSR DELAY
    LDA VOLUME  ;See if VOLUME=0
    BNE MP19
    LDA # <IM4  ;Point to
    STA IMAGEPTR ;1st crashing
    LDA # >IM4  ;skier
    STA IMAGEPTR+1 ;image
    JSR DRAW
    LDX #30
    JSR DELAY
    LDA # <IM5  ;Point to
    STA IMAGEPTR ;2nd crashing
    LDA # >IM5  ;skier
    STA IMAGEPTR+1 ;image
    JSR DRAW
    JSR DELAY
    JSR DELAY
    JSR DELAY
    LDA #0      ;Enable
    STA SCROLFLG ;scroll again
    LDA # <IM2  ;Stand
    STA IMAGEPTR ;skier
    LDA # >IM2  ;up
    STA IMAGEPTR+1 ;again
    LDA #1      ;Reset speed
    STA SPEED   ;to slow
    JMP DRAW
;
;Clear screen's 3rd line
;-----------------------
;
CLEAR3RD LDA #0
    LDY #120
MP20 STA (SAVMSC),Y
    DEY
    CPY #79
    BNE MP20
    RTS
;
;Test skier's X position
;-----------------------
;
TESTX LDA XPOS
    CMP #47
    BNE MP21
    INC XPOS
    RTS
;
MP21 CMP #196
    BNE MP22
    DEC XPOS
MP22 RTS
;
;VERTICAL BLANK INTERRUPT
;------------------------
;
VBI LDA SCROLFLG ;If not 0 do
    BNE VBICLOCK ;not scroll
;
;Calculate scroll speed
;----------------------
;
    LDA SPEED   ;Current speed
    LSR A       ;/2
    LSR A       ;/4
    LSR A       ;/8
    LSR A       ;/16 If not zero
    BNE VB1     ;do fine scroll
    LDX #1      ;If 0 make it 1
    BNE SCROLLON
;
VB1 TAX
;
;Perform fine scroll
;-------------------
;
SCROLLON INC SCROLLED ;lines scrolled
    LDA SCROLLED
    STA VSCROL  ;put in vscrol
    CMP #16     ;reached limit?
    BEQ COARSE  ;coarse scroll
    DEX         ;No. Scroll until
    BNE SCROLLON ;X=0
    BEQ VBICLOCK ;Handle clock
;
;Do a coarse scroll
;------------------
;
COARSE LDA #0   ;Reset the fine
    STA VSCROL  ;scroll reg and #
    STA SCROLLED ;lines scrolled
    LDA DLIST+9 ;DLIST's LO byte
    CLC
    ADC #40     ;Add 40 (1 line)
    STA DLIST+9 ;New LO byte
    BCC COMPEND ;Over 256? No.
    INC DLIST+10 ;Inc HI byte
;
;Check on scrolling limit
;------------------------
;
COMPEND LDA TIMESFLG
    BNE COMPDONE ;check scrolling
    LDA DLIST+10 ;DLIST HI byte
    CMP # >SCRN4 ;Reached end?
    BNE VBICLOCK ;No, skip this
    LDA DLIST+9 ;Examine LO byte
    CMP # <SCRN4 ;LO byte limit?
    BNE VBICLOCK ;No, Go on
    LDA # >SCRN1 ;Yes!
    STA DLIST+10 ;Flip back to
    LDA # <SCRN1 ;beginning of
    STA DLIST+9 ;course
    INC TIMES   ;Inc # of times
    LDA TIMES   ;course scrolled
    CMP #10     ;10 times?
    BNE VBICLOCK ;No
    LDA #1
    STA TIMESFLG ;Set times flag
    BNE VBICLOCK
;
;See if end of scrolling reached
;-------------------------------
;
COMPDONE LDA DLIST+10 ;DLIST HI byte
    CMP # >SCRLFIN ;Reached?
    BNE VBICLOCK ;No
    LDA DLIST+9 ;DLIST LO byte
    CMP # <SCRLFIN ;Reached?
    BNE VBICLOCK ;No
    LDA #1      ;Set scroll flag
    STA SCROLFLG
;
;Clock routine
;-------------
;
VBICLOCK INC CLOCK ;Inc the 60ths
    LDA CLOCK
    CMP #6      ;6/60ths yet?
    BNE PRTCLOCK ;No
    LDA #0
    STA CLOCK   ;Reset to zero
    INC CLOCK+1 ;Inc 10ths cntr
    LDA CLOCK+1
    CMP #10     ;10/10ths yet?
    BNE PRTCLOCK ;Clock on scrn
    LDA #0      ;Yes!
    STA CLOCK+1 ;Reset to zero
    INC CLOCK+3 ;Inc seconds cntr
    LDA CLOCK+3
    CMP #10     ;10 secs. yet?
    BNE PRTCLOCK ;No, branch
    LDA #0      ;Yes!
    STA CLOCK+3 ;Reset to zero
    INC CLOCK+4 ;Inc 10s of secs
    LDA CLOCK+4
    CMP #6      ;60 seconds yet?
    BNE PRTCLOCK ;No, branch
    LDA #0      ;Yes!
    STA CLOCK+4 ;Reset to zero
    INC CLOCK+6 ;Inc minutes cntr
;
;Print clock on screen
;---------------------
;
PRTCLOCK LDY #87
    LDX #6
VB2 LDA CLOCK,X ;Get a character
    CLC
    ADC #208    ;Make screen val
    STA (SAVMSC),Y ;Put on scrn
    INY
    DEX
    BNE VB2
    JMP SYSVBV
;
;SCROLLING SCRN DATA
;---------------------
;
SCRNBASE .BYTE 0,50,51,52,53,54,0,0,0
    .BYTE 169,192,0,0,0,0,209,210
    .BYTE 0,0,0,0,209,210,0,27,70
    .BYTE 0,0,0,0,69,70,0,0,0,0,0
    .BYTE 0,0,0,55,56,57,58,59,60
    .BYTE 61,0,65,66,67,68,34,35
    .BYTE 0,214,0,0,0,0,0,214,29
    .BYTE 30,31,32,33,0,0,71,72
    .BYTE 73,74,0,0,0,0,0,0,0,0
    .BYTE 69,70,0,0,40,41,42,43,0
    .BYTE 0,0,37,38,39,0,0,0,0,0
    .BYTE 0,0,0,0,0,40,41,42,43,0
    .BYTE 0,0,0,41,64,0,0,0,0,0
    .BYTE 71,72,73,74,44,45,46,47
    .BYTE 48,49,0,0,0,0,0,0,0,0,0
    .BYTE 0,0,0,0,0,44,45,46,47
    .BYTE 48,49,0,0,65,66,67,68,0
    .BYTE 0,0,0,75,76,77,0,41,64
    .BYTE 0,0,0,0,0,0,41,64,0,0,0
    .BYTE 0,0,0,0,0,0,0,0,0,0,34
    .BYTE 35,36,0,69,28,0,0,0,0,0
    .BYTE 0,0,78,79,80,65,66,67
    .BYTE 68,0,69,70,0,65,66,67,0
    .BYTE 0,212,213,128,0,0,0,212
    .BYTE 213,0,0,0,37,38,39,71
    .BYTE 72,73,74,0,0,0,0,0,0,0
    .BYTE 26,27,28,0,0,0,71,72,73
    .BYTE 74,69,28,0,0,41,64,215
    .BYTE 0,0,0,0,0,215,0,0,0,40
    .BYTE 41,42,43,0,0,26,27,28,0
    .BYTE 0,0,0,29,30,31,32,33,0
    .BYTE 34,35,36,0,71,72,73,74
    .BYTE 65,66,67,68,0,0,0,0,0,0
    .BYTE 0,0,44,45,46,47,48,49
    .BYTE 29,30,31,32,33,0,0,0,0
    .BYTE 0,0,0,0,0,37,38,39,40
    .BYTE 41,42,43,0,0,0,0,0,0,0
    .BYTE 0,0,0,0,0,0,0,0,0,0,0
    .BYTE 41,64,0,0,34,35,36,0,0
    .BYTE 0,27,28,0,0,69,70,0,44
    .BYTE 45,46,47,48,49,0,0,0,0
    .BYTE 0,0,0,0,0,0,0,0,27,70,0
    .BYTE 0,65,66,67,68,0,37,38
    .BYTE 39,0,0,71,72,73,74,71
    .BYTE 72,73,74,0,0,0,0,209
    .BYTE 210,0,0,0,128,209,210,0
    .BYTE 0,0,0,0,71,72,73,74,0,0
    .BYTE 0,0,34,35,36,0,0,0,0,75
    .BYTE 76,77,0,50,51,52,53,54
    .BYTE 0,0,0,214,0,0,0,0,0,214
    .BYTE 0,0,69,70,0,0,41,64,0,0
    .BYTE 26,27,28,0,37,38,39,0
    .BYTE 69,70,0,78,79,80,55,56
    .BYTE 57,58,59,60,61,0,0,0,0
    .BYTE 0,0,0,0,0,0,71,72,73,74
    .BYTE 65,66,67,68,29,30,31,32
    .BYTE 33,0,0,0,71,72,73,0,0,0
    .BYTE 26,27,28,0,0,0,0,0,41
    .BYTE 64,0,0,0,0,0,0,0,0,0,0
    .BYTE 0,41,64,0,0,75,76,77,0
    .BYTE 0,0,40,41,42,43,0,0,0,0
    .BYTE 29,30,31,32,33,0,0,0,65
    .BYTE 66,67,68,0,0,0,0,0,0,0
    .BYTE 0,0,65,66,67,68,0,78,79
    .BYTE 80,0,0,44,45,46,47,48
    .BYTE 49,0,0,0,50,51,52,53,54
    .BYTE 0,0,0,0,0,0,69,70,0,128
    .BYTE 209,210,0,0,128,128,209
    .BYTE 210,0,27,70,0,0,0,0,34
    .BYTE 35,36,0,0,41,64,0,0,55
    .BYTE 56,57,58,59,60,61,34,35
    .BYTE 36,0,71,72,73,74,0,214
    .BYTE 0,0,0,0,0,214,29,30,31
    .BYTE 32,33,0,0,0,37,38,39,0
    .BYTE 65,66,67,68,0,0,0,0,0
    .BYTE 34,35,0,37,38,40,41,42
    .BYTE 43,0,0,0,0,0,0,0,0,0,0
    .BYTE 0,0,0,0,69,28,0,0,27,70
    .BYTE 0,0,0,0,0,0,0,0,0,0,0
    .BYTE 37,38,39,0,44,45,46,47
    .BYTE 48,49,0,0,0,0,0,0,0,0,0
    .BYTE 0,0,0,71,72,73,74,71,72
    .BYTE 73,74,0,27,70,0,0,0,0
    .BYTE 41,64,0,0,0,27,70,0,0,0
    .BYTE 0,0,26,27,28,0,0,0,0,0
    .BYTE 0,0,0,0,0,0,0,0,41,64,0
    .BYTE 0,29,30,31,32,33,0,0,65
    .BYTE 66,67,68,29,30,31,32,33
    .BYTE 0,0,0,29,30,31,32,33,75
    .BYTE 76,77,212,213,0,0,0,128
    .BYTE 212,213,65,66,67,68,0
    .BYTE 69,70,0,0,0,0,0,0,0,27
    .BYTE 70,0,0,0,0,0,40,41,42
    .BYTE 43,0,0,0,0,78,79,80,0
    .BYTE 215,0,0,0,0,0,215,0,0,0
    .BYTE 0,71,72,73,74,0,0,0,0
    .BYTE 29,30,31,32,33,0,0,0,44
    .BYTE 45,46,47,48,49,0,0,0,0
    .BYTE 0,0,0,0,0,0,0,0,0,0,0,0
    .BYTE 41,64,0,0,26,27,28,0,0
    .BYTE 0,0,0,0,0,0,75,76,77,0
    .BYTE 0,0,0,0,0,75,76,77,0,0
    .BYTE 0,0,0,0,0,0,0,0,0,0,65
    .BYTE 66,67,68,29,30,31,32,33
    .BYTE 0,0,0,41,64,0,0,78,79
    .BYTE 80,0,69,70,0,0,0,78,79
    .BYTE 80,0,0,0,0,0,0,0,0,0,0
    .BYTE 34,35,36,0,0,41,64,0,0
    .BYTE 69,28,0,0,65,66,67,68,0
    .BYTE 27,70,0,71,72,73,74,34
    .BYTE 35,36,0,0,212,213,0,0,0
    .BYTE 0,212,213,0,0,37,38,39
    .BYTE 0,65,66,67,68,71,72,73
    .BYTE 74,0,0,0,0,0,71,72,73
    .BYTE 74,0,0,0,0,37,38,39,0,0
    .BYTE 0,215,0,0,0,0,0,215,0,0
    .BYTE 0,0,0,69,70,0,0,0,0,0,0
    .BYTE 0,0,0,168,169,170,171,0
    .BYTE 0,0,26,27,28,0,0,0,0,0
    .BYTE 0,0,0,0,0,0,0,0,0,40,41
    .BYTE 42,43,71,72,73,74,0,75
    .BYTE 76,77,0,0,0,172,173,46
    .BYTE 47,48,49,0,29,30,31,32
    .BYTE 33,0,0,41,64,0,0,0,0,0
    .BYTE 0,0,0,44,45,46,47,48,49
    .BYTE 0,41,64,0,78,79,80,0,0
    .BYTE 0,0,0,0,0,197,198,0,0,0
    .BYTE 128,0,0,0,65,66,67,68,0
    .BYTE 0,0,0,0,0,0,0,0,0,0,0,0
    .BYTE 65,66,67,68,0,26,27,28
    .BYTE 0,0,0,0,0,71,72,73,74,0
    .BYTE 41,64,0,0,0,0,0,0,209
    .BYTE 210,128,0,128,128,209
    .BYTE 210,0,0,50,51,52,53,54
    .BYTE 0,0,0,29,30,31,32,33,0
    .BYTE 0,0,0,0,0,0,0,65,66,67
    .BYTE 68,0,0,0,0,0,214,0,0,0
    .BYTE 0,0,214,0,0,55,56,57,58
    .BYTE 59,60,61,0,0,27,70,0,0
    .BYTE 0,0,0,0,27,70,0,0,34,35
    .BYTE 36,0,0,40,41,42,43,0,0
    .BYTE 0,0,0,0,0,0,69,70,0,0
    .BYTE 41,64,0,0,0,29,30,31,32
    .BYTE 33,0,0,0,0,71,72,73,74
    .BYTE 0,37,38,39,0,44,45,46
    .BYTE 47,48,49,0,0,0,0,0,0,71
    .BYTE 72,73,74,65,66,67,68,0
    .BYTE 41,42,43,0,0,34,35,0,0
    .BYTE 0,41,64,0,0,0,0,0,75,76
    .BYTE 77,0,0,0,0,0,0,0,0,0
    .BYTE 0,0,0,0,0,41,64,0,0,44
    .BYTE 45,46,47,48,49,0,37,38
    .BYTE 0,0,65,66,67,68,0,0,0,0
    .BYTE 0,79,80,0,0,0,0,0,0,0,0
    .BYTE 0,0,0,0,0,65,66,67,68,0
    .BYTE 0,0,0,0,0,0,0,0,0,0,0
;
   Org  $02E0
;
  .WORD PRGSTART