Game 1 Unit 13 of 64 1 hr learning time
Timer
60 seconds to reach home. Timer counts down. Time bonus for speed.
20% of Signal
What You’re Building
Time pressure.
A game without urgency is just a leisurely stroll. This unit adds a 60-second countdown timer. Reach a home before time runs out or die trying. Move faster to earn bonus points.
By the end of this unit:
- 60 second timer per attempt
- Timer displayed on screen
- Timeout = death
- Faster = more bonus points
The Timer Variable
We store the timer as a frame count. At 50Hz PAL, 60 seconds equals 3000 frames:
; Timer constants
TIMER_START equ 3000 ; 60 seconds at 50Hz PAL (60 * 50)
TIMER_X equ 56 ; Pixel X position for timer (left side)
TIMER_Y equ 236 ; Same row as score
TIMER_DIGITS equ 2 ; Display 2 digits (00-60)
; Timer variable
timer: dc.w 3000 ; Countdown timer in frames
timer_digits: dc.w 0,0 ; Buffer for 2 decimal digits
Using frames instead of seconds gives us precise control. The timer decrements once per frame in the main loop.
Updating the Timer
Each frame, we subtract 1 from the timer. When it hits zero, the frog dies:
;------------------------------------------------------------------------------
; UPDATE_TIMER - Decrement timer and check for timeout
;------------------------------------------------------------------------------
update_timer:
subq.w #1,timer
bgt.s .not_timeout
; Timer reached zero - death!
bsr trigger_death
rts
.not_timeout:
; Display timer every frame
bsr display_timer
rts
The bgt.s (branch if greater than, signed) handles the comparison. When timer becomes zero or negative, we trigger death.
We skip the timer update when the frog is dying—no point counting down during the death animation:
; Update timer (only when not dying)
cmp.w #STATE_DYING,frog_state
beq.s .skip_timer
bsr update_timer
.skip_timer:Displaying Seconds
Players think in seconds, not frames. We convert frames to seconds using DIVU:
;------------------------------------------------------------------------------
; DISPLAY_TIMER - Show remaining seconds on screen
;------------------------------------------------------------------------------
display_timer:
movem.l d0-d4/a0-a3,-(sp)
; Convert timer frames to seconds (timer / 50)
move.w timer(pc),d0
ext.l d0
divu #50,d0 ; d0 = seconds remaining
; Convert to 2 decimal digits
lea timer_digits+4,a0 ; Point past end of buffer
moveq #1,d4 ; 2 digits
.convert:
divu #10,d0
swap d0
move.w d0,-(a0)
clr.w d0
swap d0
dbf d4,.convert
; Draw 2 digits using CPU byte copies
lea timer_digits,a1
lea screen_plane,a2
add.l #TIMER_Y*SCREEN_W+TIMER_X/8,a2
moveq #1,d4 ; 2 digits
.draw_digit:
move.w (a1)+,d0
lsl.w #4,d0 ; *16 for font offset
lea digit_font,a0
add.w d0,a0
move.l a2,a3
moveq #7,d3 ; 8 rows
.copy_row:
move.b (a0),(a3)
addq.l #2,a0
lea SCREEN_W(a3),a3
dbf d3,.copy_row
addq.l #1,a2 ; Next digit position
dbf d4,.draw_digit
movem.l (sp)+,d0-d4/a0-a3
rts
DIVU divides a 32-bit dividend by a 16-bit divisor. The quotient (seconds) ends up in the low word. We extend the 16-bit timer to 32 bits with ext.l before dividing.
Time Bonus
Reaching home faster should reward the player. We calculate a bonus based on remaining time:
; Time bonus calculation when reaching home
; Called from check_home after marking home as filled
; Time bonus: remaining seconds * 2 points
move.w timer(pc),d0
ext.l d0
divu #50,d0 ; Convert frames to seconds
and.l #$ffff,d0 ; Keep only quotient (mask off remainder)
add.l d0,d0 ; *2 for bonus
add.l d0,score ; Add time bonus
; If player reaches home with 30 seconds remaining:
; 30 * 2 = 60 bonus points added to score
If you reach home with 30 seconds remaining, you earn 60 bonus points (30 × 2). The faster you move, the bigger the reward. The and.l #$ffff,d0 masks off the remainder in the high word, keeping only the quotient.
Resetting the Timer
The timer resets in two places:
Game initialisation (new game):
init_game:
move.w #START_LIVES,lives
clr.l score
move.w #TIMER_START,timer ; Reset timerFrog reset (after reaching home or death):
reset_frog:
; ... other reset code ...
move.w #TIMER_START,timer ; Reset timer for new attemptEach attempt starts fresh with 60 seconds.
Display Position
We place the timer on the left side of the start zone, opposite the score:
TIMER_X equ 56 ; Pixel X position (left side)
TIMER_Y equ 236 ; Same row as score
TIMER_DIGITS equ 2 ; 2 digits (00-60)Two digits suffice since the timer never exceeds 60 seconds.
The Urgency Effect
The timer transforms gameplay. Without it, players could wait forever for a safe gap. With it, they must take risks. The countdown creates tension—especially in the final seconds.
The time bonus adds another layer: do you play safe and just survive, or push for speed and higher scores?
Key Takeaways
- Frame-based timing gives precise control (3000 frames = 60 seconds)
- DIVU converts frames to displayable seconds
- Timeout triggers death via existing trigger_death routine
- Time bonus rewards faster play (remaining seconds × 2)
- Timer resets on each new attempt
- Urgency transforms leisurely play into tense action
The Code
;==============================================================================
; SIGNAL - A Frogger-style game for the Commodore Amiga
; Unit 13: Timer
;
; Time pressure creates urgency. This unit adds a 60-second countdown timer.
; Run out of time and you die. Reach home faster to earn bonus points.
;==============================================================================
;==============================================================================
; CONSTANTS
;==============================================================================
SCREEN_W equ 40
SCREEN_H equ 256
PLANE_SIZE equ SCREEN_W*SCREEN_H
GRID_COLS equ 20
GRID_ROWS equ 13
CELL_SIZE equ 16
GRID_ORIGIN_X equ 48
GRID_ORIGIN_Y equ 44
START_GRID_X equ 9
START_GRID_Y equ 12
HOP_FRAMES equ 8
PIXELS_PER_FRAME equ 2
STATE_IDLE equ 0
STATE_HOPPING equ 1
STATE_DYING equ 2
STATE_GAMEOVER equ 3
DIR_UP equ 0
DIR_DOWN equ 1
DIR_LEFT equ 2
DIR_RIGHT equ 3
FROG_HEIGHT equ 16
FROG_WIDTH equ 16
DEATH_FRAMES equ 30
FLASH_COLOUR equ $0f00
NUM_CARS equ 10
CAR_WIDTH equ 2
CAR_WIDTH_PX equ 32
CAR_HEIGHT equ 12
CAR_STRUCT_SIZE equ 8
ROAD_ROW_FIRST equ 7
ROAD_ROW_LAST equ 11
START_LIVES equ 3
NUM_HOMES equ 5
HOME_ROW equ 0
POINTS_PER_HOME equ 50
HOME_0_X equ 2
HOME_1_X equ 6
HOME_2_X equ 10
HOME_3_X equ 14
HOME_4_X equ 18
; Score display - position in start zone (below cars)
SCORE_X equ 256 ; Pixel X position (must be byte-aligned)
SCORE_Y equ 236 ; Pixel Y position (grid row 12, in start zone)
DIGIT_H equ 8 ; 8 pixels tall
NUM_DIGITS equ 6 ; Display 6 digits (up to 999,999)
; Timer constants
TIMER_START equ 3000 ; 60 seconds at 50Hz PAL (60 * 50)
TIMER_X equ 56 ; Pixel X position for timer (left side)
TIMER_Y equ 236 ; Same row as score
TIMER_DIGITS equ 2 ; Display 2 digits (00-60)
; Audio constants
SND_HOP equ 0
SND_DEATH equ 1
SND_HOME equ 2
; Colours
COLOUR_BLACK equ $0000
COLOUR_HOME equ $0282
COLOUR_HOME_LIT equ $03a3
COLOUR_HOME_FILLED equ $0f80
COLOUR_WATER1 equ $0148
COLOUR_WATER2 equ $026a
COLOUR_MEDIAN equ $0383
COLOUR_ROAD1 equ $0333
COLOUR_ROAD2 equ $0444
COLOUR_START equ $0262
COLOUR_START_LIT equ $0373
COLOUR_FROG equ $00f0
COLOUR_EYES equ $0ff0
COLOUR_OUTLINE equ $0000
COLOUR_CAR equ $0f00
;==============================================================================
; HARDWARE REGISTERS
;==============================================================================
CUSTOM equ $dff000
DMACONR equ $002
VPOSR equ $004
JOY1DAT equ $00c
BLTCON0 equ $040
BLTCON1 equ $042
BLTAFWM equ $044
BLTALWM equ $046
BLTCPTH equ $048
BLTBPTH equ $04c
BLTAPTH equ $050
BLTDPTH equ $054
BLTSIZE equ $058
BLTCMOD equ $060
BLTBMOD equ $062
BLTAMOD equ $064
BLTDMOD equ $066
BLTADAT equ $074
COP1LC equ $080
COPJMP1 equ $088
DMACON equ $096
INTENA equ $09a
INTREQ equ $09c
COLOR00 equ $180
SPR0PTH equ $120
SPR0PTL equ $122
SPR1PTH equ $124
SPR1PTL equ $126
SPR2PTH equ $128
SPR2PTL equ $12a
AUD0LC equ $0a0
AUD0LEN equ $0a4
AUD0PER equ $0a6
AUD0VOL equ $0a8
;==============================================================================
; CODE SECTION
;==============================================================================
section code,code_c
start:
lea CUSTOM,a5
move.w #$7fff,INTENA(a5)
move.w #$7fff,INTREQ(a5)
move.w #$7fff,DMACON(a5)
; Enable Blitter DMA for screen clearing and drawing
move.w #$8040,DMACON(a5) ; BLTDMA on
bsr clear_screen
; Set up bitplane pointer
lea screen_plane,a0
move.l a0,d0
swap d0
lea bplpth_val,a1
move.w d0,(a1)
swap d0
lea bplptl_val,a1
move.w d0,(a1)
; Initialise game
bsr init_game
; Set main sprite pointer
lea frog_data,a0
move.l a0,d0
swap d0
lea sprpth_val,a1
move.w d0,(a1)
swap d0
lea sprptl_val,a1
move.w d0,(a1)
bsr setup_life_sprites
bsr update_sprite
bsr update_life_display
; Install copper list
lea copperlist,a0
move.l a0,COP1LC(a5)
move.w d0,COPJMP1(a5)
move.w #$87e1,DMACON(a5)
; Display score and timer after all DMA enabled
bsr display_score
bsr display_timer
;==============================================================================
; MAIN LOOP
;==============================================================================
mainloop:
bsr wait_vblank
cmp.w #STATE_GAMEOVER,frog_state
beq .game_over_loop
bsr update_frog
bsr update_sprite
; Update timer (only when not dying)
cmp.w #STATE_DYING,frog_state
beq.s .skip_timer
bsr update_timer
.skip_timer:
bsr erase_all_cars
bsr move_all_cars
bsr draw_all_cars
cmp.w #STATE_DYING,frog_state
beq.s .skip_collision
cmp.w #STATE_IDLE,frog_state
bne.s .skip_collision
bsr check_home
bsr check_collision
.skip_collision:
bra mainloop
.game_over_loop:
btst #7,$bfe001
bne.s mainloop
bsr init_game
bsr update_life_display
bsr display_score
bsr display_timer
bsr clear_screen
bra mainloop
;==============================================================================
; SCORE DISPLAY
;==============================================================================
;------------------------------------------------------------------------------
; DISPLAY_SCORE - Convert score to digits and display
; Simplified: just draws "000000" for now
;------------------------------------------------------------------------------
display_score:
movem.l d0-d4/a0-a3,-(sp)
; Convert score to 6 decimal digits
move.l score(pc),d0 ; Use PC-relative addressing
lea score_digits+12,a0 ; Point past end of buffer
moveq #5,d4
.convert:
divu #10,d0 ; d0 low = quotient, d0 high = remainder
swap d0
move.w d0,-(a0) ; Store remainder
clr.w d0
swap d0
dbf d4,.convert
; Draw 6 digits using CPU byte copies (tight 8-pixel spacing)
lea score_digits,a1 ; Digit values
lea screen_plane,a2
add.l #SCORE_Y*SCREEN_W+SCORE_X/8,a2 ; Base destination
moveq #5,d4 ; 6 digits
.draw_digit:
move.w (a1)+,d0 ; Get digit value (0-9)
lsl.w #4,d0 ; *16: each digit = 16 bytes
lea digit_font,a0
add.w d0,a0 ; Point to correct digit
; Copy 8 rows, 1 byte each (CPU, no alignment issues)
move.l a2,a3 ; Dest for this digit
moveq #7,d3 ; 8 rows
.copy_row:
move.b (a0),(a3) ; Copy high byte of word
addq.l #2,a0 ; Next source word
lea SCREEN_W(a3),a3 ; Next dest row
dbf d3,.copy_row
addq.l #1,a2 ; Move right by 1 byte (8 pixels)
dbf d4,.draw_digit
movem.l (sp)+,d0-d4/a0-a3
rts
;==============================================================================
; TIMER ROUTINES
;==============================================================================
;------------------------------------------------------------------------------
; UPDATE_TIMER - Decrement timer and check for timeout
;------------------------------------------------------------------------------
update_timer:
subq.w #1,timer
bgt.s .not_timeout
; Timer reached zero - death!
bsr trigger_death
rts
.not_timeout:
; Display timer every frame
bsr display_timer
rts
;------------------------------------------------------------------------------
; DISPLAY_TIMER - Show remaining seconds on screen
;------------------------------------------------------------------------------
display_timer:
movem.l d0-d4/a0-a3,-(sp)
; Convert timer frames to seconds (timer / 50)
move.w timer(pc),d0
ext.l d0
divu #50,d0 ; d0 = seconds remaining
; Convert to 2 decimal digits
lea timer_digits+4,a0 ; Point past end of buffer
moveq #1,d4 ; 2 digits
.convert:
divu #10,d0
swap d0
move.w d0,-(a0)
clr.w d0
swap d0
dbf d4,.convert
; Draw 2 digits using CPU byte copies
lea timer_digits,a1
lea screen_plane,a2
add.l #TIMER_Y*SCREEN_W+TIMER_X/8,a2
moveq #1,d4 ; 2 digits
.draw_digit:
move.w (a1)+,d0
lsl.w #4,d0 ; *16 for font offset
lea digit_font,a0
add.w d0,a0
move.l a2,a3
moveq #7,d3 ; 8 rows
.copy_row:
move.b (a0),(a3)
addq.l #2,a0
lea SCREEN_W(a3),a3
dbf d3,.copy_row
addq.l #1,a2 ; Next digit position
dbf d4,.draw_digit
movem.l (sp)+,d0-d4/a0-a3
rts
;------------------------------------------------------------------------------
; CALC_PIXEL_ADDR - Calculate screen address for pixel coordinates
; Input: D0 = X, D1 = Y
; Output: A2 = screen address
;------------------------------------------------------------------------------
calc_pixel_addr:
lea screen_plane,a2
move.w d1,d2
mulu #SCREEN_W,d2
add.l d2,a2
move.w d0,d2
lsr.w #3,d2
ext.l d2
add.l d2,a2
rts
;==============================================================================
; SOUND ROUTINES
;==============================================================================
play_sound:
cmp.w #SND_HOP,d0
beq.s .play_hop
cmp.w #SND_DEATH,d0
beq.s .play_death
cmp.w #SND_HOME,d0
beq.s .play_home
rts
.play_hop:
lea sound_hop,a0
move.w #HOP_LEN/2,d1
move.w #300,d2
bra.s .do_play
.play_death:
lea sound_death,a0
move.w #DEATH_LEN/2,d1
move.w #500,d2
bra.s .do_play
.play_home:
lea sound_home,a0
move.w #HOME_LEN/2,d1
move.w #200,d2
.do_play:
move.w #$0001,DMACON(a5)
move.l a0,AUD0LC(a5)
move.w d1,AUD0LEN(a5)
move.w d2,AUD0PER(a5)
move.w #64,AUD0VOL(a5)
move.w #$8001,DMACON(a5)
rts
;==============================================================================
; GAME INITIALISATION
;==============================================================================
init_game:
move.w #START_LIVES,lives
clr.l score
move.w #TIMER_START,timer ; Reset timer
lea home_filled,a0
moveq #NUM_HOMES-1,d0
.clear_homes:
clr.w (a0)+
dbf d0,.clear_homes
bsr update_home_display
bsr reset_frog
rts
;==============================================================================
; HOME ZONE DETECTION
;==============================================================================
check_home:
move.w frog_grid_y,d0
tst.w d0
bne .not_home
move.w frog_grid_x,d0
cmp.w #HOME_0_X,d0
blt .not_home
cmp.w #HOME_0_X+2,d0
blt.s .home_0
cmp.w #HOME_1_X,d0
blt .not_home
cmp.w #HOME_1_X+2,d0
blt.s .home_1
cmp.w #HOME_2_X,d0
blt .not_home
cmp.w #HOME_2_X+2,d0
blt.s .home_2
cmp.w #HOME_3_X,d0
blt .not_home
cmp.w #HOME_3_X+2,d0
blt.s .home_3
cmp.w #HOME_4_X,d0
blt .not_home
cmp.w #HOME_4_X+2,d0
blt.s .home_4
bra .death_between
.home_0: moveq #0,d1
bra.s .check_filled
.home_1: moveq #1,d1
bra.s .check_filled
.home_2: moveq #2,d1
bra.s .check_filled
.home_3: moveq #3,d1
bra.s .check_filled
.home_4: moveq #4,d1
.check_filled:
lea home_filled,a0
add.w d1,d1
tst.w 0(a0,d1.w)
bne.s .death_filled
move.w #1,0(a0,d1.w)
add.l #POINTS_PER_HOME,score
; Time bonus: remaining seconds * 2 points
move.w timer(pc),d0
ext.l d0
divu #50,d0 ; Convert frames to seconds
and.l #$ffff,d0 ; Keep only quotient
add.l d0,d0 ; *2 for bonus
add.l d0,score ; Add time bonus
move.w #SND_HOME,d0
bsr play_sound
bsr update_home_display
bsr display_score ; Update score display
bsr check_round_complete
bsr reset_frog
rts
.death_filled:
.death_between:
bsr trigger_death
rts
.not_home:
rts
check_round_complete:
lea home_filled,a0
moveq #NUM_HOMES-1,d0
moveq #0,d1
.loop:
tst.w (a0)+
beq.s .not_complete
addq.w #1,d1
dbf d0,.loop
cmp.w #NUM_HOMES,d1
bne.s .not_complete
lea home_filled,a0
moveq #NUM_HOMES-1,d0
.clear:
clr.w (a0)+
dbf d0,.clear
bsr update_home_display
.not_complete:
rts
update_home_display:
lea home_filled,a0
lea home_colour_0,a1
tst.w (a0)+
beq.s .home0_empty
move.w #COLOUR_HOME_FILLED,(a1)
bra.s .home1
.home0_empty:
move.w #COLOUR_HOME_LIT,(a1)
.home1:
lea home_colour_1,a1
tst.w (a0)+
beq.s .home1_empty
move.w #COLOUR_HOME_FILLED,(a1)
bra.s .home2
.home1_empty:
move.w #COLOUR_HOME_LIT,(a1)
.home2:
lea home_colour_2,a1
tst.w (a0)+
beq.s .home2_empty
move.w #COLOUR_HOME_FILLED,(a1)
bra.s .home3
.home2_empty:
move.w #COLOUR_HOME_LIT,(a1)
.home3:
lea home_colour_3,a1
tst.w (a0)+
beq.s .home3_empty
move.w #COLOUR_HOME_FILLED,(a1)
bra.s .home4
.home3_empty:
move.w #COLOUR_HOME_LIT,(a1)
.home4:
lea home_colour_4,a1
tst.w (a0)+
beq.s .home4_empty
move.w #COLOUR_HOME_FILLED,(a1)
rts
.home4_empty:
move.w #COLOUR_HOME_LIT,(a1)
rts
;==============================================================================
; LIFE DISPLAY
;==============================================================================
setup_life_sprites:
lea life_icon_1,a0
move.l a0,d0
swap d0
lea spr1pth_val,a1
move.w d0,(a1)
swap d0
lea spr1ptl_val,a1
move.w d0,(a1)
lea life_icon_2,a0
move.l a0,d0
swap d0
lea spr2pth_val,a1
move.w d0,(a1)
swap d0
lea spr2ptl_val,a1
move.w d0,(a1)
lea life_icon_3,a0
move.l a0,d0
swap d0
lea spr3pth_val,a1
move.w d0,(a1)
swap d0
lea spr3ptl_val,a1
move.w d0,(a1)
rts
update_life_display:
lea life_icon_1,a0
move.w lives,d0
cmp.w #1,d0
blt.s .hide_life1
move.w #$1e20,$0(a0)
move.w #$2600,$2(a0)
bra.s .life2
.hide_life1:
clr.l (a0)
.life2:
lea life_icon_2,a0
cmp.w #2,d0
blt.s .hide_life2
move.w #$1e28,$0(a0)
move.w #$2600,$2(a0)
bra.s .life3
.hide_life2:
clr.l (a0)
.life3:
lea life_icon_3,a0
cmp.w #3,d0
blt.s .hide_life3
move.w #$1e30,$0(a0)
move.w #$2600,$2(a0)
rts
.hide_life3:
clr.l (a0)
rts
;==============================================================================
; COLLISION AND DEATH
;==============================================================================
check_collision:
move.w frog_grid_y,d0
cmp.w #ROAD_ROW_FIRST,d0
blt .no_collision
cmp.w #ROAD_ROW_LAST,d0
bgt .no_collision
lea car_data,a2
moveq #NUM_CARS-1,d7
.loop:
move.w 2(a2),d1
cmp.w d0,d1
bne.s .next_car
move.w frog_pixel_x,d2
move.w (a2),d3
move.w d2,d4
add.w #FROG_WIDTH,d4
cmp.w d3,d4
ble.s .next_car
move.w d3,d4
add.w #CAR_WIDTH_PX,d4
cmp.w d2,d4
ble.s .next_car
bsr trigger_death
bra.s .no_collision
.next_car:
lea CAR_STRUCT_SIZE(a2),a2
dbf d7,.loop
.no_collision:
rts
trigger_death:
move.w #STATE_DYING,frog_state
move.w #DEATH_FRAMES,death_timer
move.w #FLASH_COLOUR,flash_colour
move.w #SND_DEATH,d0
bsr play_sound
subq.w #1,lives
bsr update_life_display
rts
reset_frog:
move.w #START_GRID_X,frog_grid_x
move.w #START_GRID_Y,frog_grid_y
move.w #STATE_IDLE,frog_state
clr.w frog_anim_frame
clr.w joy_prev
move.w #COLOUR_BLACK,flash_colour
move.w #TIMER_START,timer ; Reset timer for new attempt
bsr grid_to_pixels
rts
;==============================================================================
; CAR MANAGEMENT
;==============================================================================
erase_all_cars:
lea car_data,a2
moveq #NUM_CARS-1,d7
.loop:
move.w (a2),d0
move.w 2(a2),d1
bsr calc_screen_addr
bsr wait_blit
move.l a0,BLTDPTH(a5)
move.w #SCREEN_W-CAR_WIDTH*2,BLTDMOD(a5)
move.w #$0100,BLTCON0(a5)
move.w #0,BLTCON1(a5)
move.w #(CAR_HEIGHT<<6)|CAR_WIDTH,BLTSIZE(a5)
lea CAR_STRUCT_SIZE(a2),a2
dbf d7,.loop
rts
move_all_cars:
lea car_data,a2
moveq #NUM_CARS-1,d7
.loop:
move.w (a2),d0
move.w 4(a2),d1
add.w d1,d0
tst.w d1
bmi.s .check_left
cmp.w #320,d0
blt.s .store
sub.w #320+32,d0
bra.s .store
.check_left:
cmp.w #-32,d0
bgt.s .store
add.w #320+32,d0
.store:
move.w d0,(a2)
lea CAR_STRUCT_SIZE(a2),a2
dbf d7,.loop
rts
draw_all_cars:
lea car_data,a2
moveq #NUM_CARS-1,d7
.loop:
move.w (a2),d0
move.w 2(a2),d1
cmp.w #-32,d0
blt.s .next
cmp.w #320,d0
bge.s .next
bsr calc_screen_addr
bsr wait_blit
move.l #car_gfx,BLTAPTH(a5)
move.l a0,BLTDPTH(a5)
move.w #$ffff,BLTAFWM(a5)
move.w #$ffff,BLTALWM(a5)
move.w #0,BLTAMOD(a5)
move.w #SCREEN_W-CAR_WIDTH*2,BLTDMOD(a5)
move.w #$09f0,BLTCON0(a5)
move.w #0,BLTCON1(a5)
move.w #(CAR_HEIGHT<<6)|CAR_WIDTH,BLTSIZE(a5)
.next:
lea CAR_STRUCT_SIZE(a2),a2
dbf d7,.loop
rts
;==============================================================================
; FROG ROUTINES
;==============================================================================
update_frog:
move.w frog_state,d0
cmp.w #STATE_DYING,d0
beq .dying
tst.w d0
beq .idle
bra .hopping
.dying:
subq.w #1,death_timer
bgt.s .still_dying
tst.w lives
beq.s .game_over
bsr reset_frog
bra .done
.game_over:
move.w #STATE_GAMEOVER,frog_state
bra .done
.still_dying:
move.w death_timer,d0
and.w #4,d0
beq.s .flash_off
move.w #FLASH_COLOUR,flash_colour
bra .done
.flash_off:
move.w #COLOUR_BLACK,flash_colour
bra .done
.idle:
bsr read_joystick_edge
tst.w d0
beq .done
btst #8,d0
beq.s .not_up
move.w frog_grid_y,d1
tst.w d1
beq.s .not_up
move.w #DIR_UP,frog_dir
bra.s .start_hop
.not_up:
btst #0,d0
beq.s .not_down
move.w frog_grid_y,d1
cmp.w #GRID_ROWS-1,d1
beq.s .not_down
move.w #DIR_DOWN,frog_dir
bra.s .start_hop
.not_down:
btst #9,d0
beq.s .not_left
move.w frog_grid_x,d1
tst.w d1
beq.s .not_left
move.w #DIR_LEFT,frog_dir
bra.s .start_hop
.not_left:
btst #1,d0
beq .done
move.w frog_grid_x,d1
cmp.w #GRID_COLS-1,d1
beq .done
move.w #DIR_RIGHT,frog_dir
.start_hop:
move.w #STATE_HOPPING,frog_state
clr.w frog_anim_frame
move.w #SND_HOP,d0
bsr play_sound
bra.s .done
.hopping:
addq.w #1,frog_anim_frame
move.w frog_dir,d0
cmp.w #DIR_UP,d0
bne.s .hop_not_up
sub.w #PIXELS_PER_FRAME,frog_pixel_y
bra.s .check_done
.hop_not_up:
cmp.w #DIR_DOWN,d0
bne.s .hop_not_down
add.w #PIXELS_PER_FRAME,frog_pixel_y
bra.s .check_done
.hop_not_down:
cmp.w #DIR_LEFT,d0
bne.s .hop_not_left
sub.w #PIXELS_PER_FRAME,frog_pixel_x
bra.s .check_done
.hop_not_left:
add.w #PIXELS_PER_FRAME,frog_pixel_x
.check_done:
cmp.w #HOP_FRAMES,frog_anim_frame
blt.s .done
move.w frog_dir,d0
cmp.w #DIR_UP,d0
bne.s .end_not_up
subq.w #1,frog_grid_y
bra.s .snap
.end_not_up:
cmp.w #DIR_DOWN,d0
bne.s .end_not_down
addq.w #1,frog_grid_y
bra.s .snap
.end_not_down:
cmp.w #DIR_LEFT,d0
bne.s .end_not_left
subq.w #1,frog_grid_x
bra.s .snap
.end_not_left:
addq.w #1,frog_grid_x
.snap:
bsr grid_to_pixels
move.w #STATE_IDLE,frog_state
.done:
move.w flash_colour,flash_copper
rts
;==============================================================================
; UTILITY ROUTINES
;==============================================================================
grid_to_pixels:
move.w frog_grid_x,d0
mulu #CELL_SIZE,d0
add.w #GRID_ORIGIN_X,d0
move.w d0,frog_pixel_x
move.w frog_grid_y,d0
mulu #CELL_SIZE,d0
add.w #GRID_ORIGIN_Y,d0
move.w d0,frog_pixel_y
rts
read_joystick_edge:
move.w JOY1DAT(a5),d0
move.w d0,d1
lsr.w #1,d1
eor.w d1,d0
move.w joy_prev,d1
not.w d1
and.w d0,d1
move.w d0,joy_prev
move.w d1,d0
rts
wait_vblank:
move.l #$1ff00,d1
.wait:
move.l VPOSR(a5),d0
and.l d1,d0
bne.s .wait
rts
wait_blit:
btst #6,DMACONR(a5)
bne.s wait_blit
rts
clear_screen:
bsr.s wait_blit
move.l #screen_plane,BLTDPTH(a5)
move.w #0,BLTDMOD(a5)
move.w #$0100,BLTCON0(a5)
move.w #0,BLTCON1(a5)
move.w #(SCREEN_H<<6)|SCREEN_W/2,BLTSIZE(a5)
rts
calc_screen_addr:
lea screen_plane,a0
move.w d1,d2
mulu #CELL_SIZE,d2
add.w #GRID_ORIGIN_Y,d2
mulu #SCREEN_W,d2
add.l d2,a0
move.w d0,d2
lsr.w #3,d2
ext.l d2
add.l d2,a0
rts
update_sprite:
lea frog_data,a0
move.w frog_pixel_y,d0
move.w frog_pixel_x,d1
move.w d0,d2
lsl.w #8,d2
lsr.w #1,d1
or.b d1,d2
move.w d2,(a0)
add.w #FROG_HEIGHT,d0
lsl.w #8,d0
move.w d0,2(a0)
rts
;==============================================================================
; VARIABLES
;==============================================================================
frog_grid_x: dc.w 9
frog_grid_y: dc.w 12
frog_pixel_x: dc.w 0
frog_pixel_y: dc.w 0
frog_state: dc.w 0
frog_dir: dc.w 0
frog_anim_frame: dc.w 0
joy_prev: dc.w 0
death_timer: dc.w 0
flash_colour: dc.w 0
lives: dc.w 3
score: dc.l 0
timer: dc.w 3000 ; Countdown timer in frames
home_filled: dc.w 0,0,0,0,0
; Buffer for score digits
score_digits: dc.w 0,0,0,0,0,0
; Buffer for timer digits (2 digits for seconds)
timer_digits: dc.w 0,0
car_data:
dc.w 0,7,1,0
dc.w 160,7,1,0
dc.w 100,8,-2,0
dc.w 250,8,-2,0
dc.w 50,9,2,0
dc.w 200,9,2,0
dc.w 80,10,-1,0
dc.w 220,10,-1,0
dc.w 30,11,3,0
dc.w 180,11,3,0
;==============================================================================
; COPPER LIST
;==============================================================================
copperlist:
dc.w COLOR00
flash_copper:
dc.w COLOUR_BLACK
dc.w $0100,$1200
dc.w $0102,$0000
dc.w $0104,$0000
dc.w $0108,$0000
dc.w $010a,$0000
dc.w $00e0
bplpth_val: dc.w $0000
dc.w $00e2
bplptl_val: dc.w $0000
dc.w $0180,$0000
dc.w $0182,COLOUR_CAR
dc.w $01a2,COLOUR_FROG
dc.w $01a4,COLOUR_EYES
dc.w $01a6,COLOUR_OUTLINE
dc.w SPR0PTH
sprpth_val: dc.w $0000
dc.w SPR0PTL
sprptl_val: dc.w $0000
dc.w SPR1PTH
spr1pth_val: dc.w $0000
dc.w SPR1PTL
spr1ptl_val: dc.w $0000
dc.w SPR2PTH
spr2pth_val: dc.w $0000
dc.w SPR2PTL
spr2ptl_val: dc.w $0000
dc.w $0126
spr3pth_val: dc.w $0000
dc.w $012a
spr3ptl_val: dc.w $0000
; Home zone row
dc.w $2c07,$fffe
dc.w COLOR00,COLOUR_HOME
dc.w $2c4f,$fffe
dc.w COLOR00
home_colour_0:
dc.w COLOUR_HOME_LIT
dc.w $2c5f,$fffe
dc.w COLOR00,COLOUR_HOME
dc.w $2c8f,$fffe
dc.w COLOR00
home_colour_1:
dc.w COLOUR_HOME_LIT
dc.w $2c9f,$fffe
dc.w COLOR00,COLOUR_HOME
dc.w $2ccf,$fffe
dc.w COLOR00
home_colour_2:
dc.w COLOUR_HOME_LIT
dc.w $2cdf,$fffe
dc.w COLOR00,COLOUR_HOME
dc.w $2d07,$fffe
dc.w COLOR00
home_colour_3:
dc.w COLOUR_HOME_LIT
dc.w $2d17,$fffe
dc.w COLOR00,COLOUR_HOME
dc.w $2d47,$fffe
dc.w COLOR00
home_colour_4:
dc.w COLOUR_HOME_LIT
dc.w $2d57,$fffe
dc.w COLOR00,COLOUR_HOME
dc.w $3407,$fffe
dc.w COLOR00,COLOUR_HOME_LIT
dc.w $3807,$fffe
dc.w COLOR00,COLOUR_HOME
dc.w $3c07,$fffe
dc.w COLOR00,COLOUR_WATER1
dc.w $4c07,$fffe
dc.w COLOR00,COLOUR_WATER2
dc.w $5c07,$fffe
dc.w COLOR00,COLOUR_WATER1
dc.w $6c07,$fffe
dc.w COLOR00,COLOUR_WATER2
dc.w $7c07,$fffe
dc.w COLOR00,COLOUR_WATER1
dc.w $8c07,$fffe
dc.w COLOR00,COLOUR_MEDIAN
dc.w $9c07,$fffe
dc.w COLOR00,COLOUR_ROAD1
dc.w $ac07,$fffe
dc.w COLOR00,COLOUR_ROAD2
dc.w $bc07,$fffe
dc.w COLOR00,COLOUR_ROAD1
dc.w $cc07,$fffe
dc.w COLOR00,COLOUR_ROAD2
dc.w $dc07,$fffe
dc.w COLOR00,COLOUR_ROAD1
dc.w $ec07,$fffe
dc.w COLOR00,COLOUR_START
dc.w $f407,$fffe
dc.w COLOR00,COLOUR_START_LIT
dc.w $f807,$fffe
dc.w COLOR00,COLOUR_START
dc.w $fc07,$fffe
dc.w COLOR00,COLOUR_BLACK
dc.w $ffff,$fffe
;==============================================================================
; GRAPHICS DATA
;==============================================================================
even
car_gfx:
dc.w $0ff0,$0ff0
dc.w $3ffc,$3ffc
dc.w $7ffe,$7ffe
dc.w $ffff,$ffff
dc.w $ffff,$ffff
dc.w $ffff,$ffff
dc.w $ffff,$ffff
dc.w $ffff,$ffff
dc.w $ffff,$ffff
dc.w $7ffe,$7ffe
dc.w $3c3c,$3c3c
dc.w $0000,$0000
even
frog_data:
dc.w $ec50,$fc00
dc.w $0000,$0000
dc.w $07e0,$0000
dc.w $1ff8,$0420
dc.w $3ffc,$0a50
dc.w $7ffe,$1248
dc.w $7ffe,$1008
dc.w $ffff,$2004
dc.w $ffff,$0000
dc.w $ffff,$0000
dc.w $7ffe,$2004
dc.w $7ffe,$1008
dc.w $3ffc,$0810
dc.w $1ff8,$0420
dc.w $07e0,$0000
dc.w $0000,$0000
dc.w $0000,$0000
dc.w $0000,$0000
even
life_icon_1:
dc.w $0000,$0000
dc.w $0000,$0000
dc.w $1800,$0000
dc.w $3c00,$0000
dc.w $7e00,$0000
dc.w $7e00,$0000
dc.w $3c00,$0000
dc.w $1800,$0000
dc.w $0000,$0000
dc.w $0000,$0000
even
life_icon_2:
dc.w $0000,$0000
dc.w $0000,$0000
dc.w $1800,$0000
dc.w $3c00,$0000
dc.w $7e00,$0000
dc.w $7e00,$0000
dc.w $3c00,$0000
dc.w $1800,$0000
dc.w $0000,$0000
dc.w $0000,$0000
even
life_icon_3:
dc.w $0000,$0000
dc.w $0000,$0000
dc.w $1800,$0000
dc.w $3c00,$0000
dc.w $7e00,$0000
dc.w $7e00,$0000
dc.w $3c00,$0000
dc.w $1800,$0000
dc.w $0000,$0000
dc.w $0000,$0000
; Digit font (in Chip RAM via code_c section)
even
digit_font:
; 0
dc.w $3c00
dc.w $6600
dc.w $6e00
dc.w $7e00
dc.w $7600
dc.w $6600
dc.w $3c00
dc.w $0000
; 1
dc.w $1800
dc.w $3800
dc.w $1800
dc.w $1800
dc.w $1800
dc.w $1800
dc.w $7e00
dc.w $0000
; 2
dc.w $3c00
dc.w $6600
dc.w $0600
dc.w $1c00
dc.w $3000
dc.w $6000
dc.w $7e00
dc.w $0000
; 3
dc.w $3c00
dc.w $6600
dc.w $0600
dc.w $1c00
dc.w $0600
dc.w $6600
dc.w $3c00
dc.w $0000
; 4
dc.w $0c00
dc.w $1c00
dc.w $3c00
dc.w $6c00
dc.w $7e00
dc.w $0c00
dc.w $0c00
dc.w $0000
; 5
dc.w $7e00
dc.w $6000
dc.w $7c00
dc.w $0600
dc.w $0600
dc.w $6600
dc.w $3c00
dc.w $0000
; 6
dc.w $1c00
dc.w $3000
dc.w $6000
dc.w $7c00
dc.w $6600
dc.w $6600
dc.w $3c00
dc.w $0000
; 7
dc.w $7e00
dc.w $0600
dc.w $0c00
dc.w $1800
dc.w $3000
dc.w $3000
dc.w $3000
dc.w $0000
; 8
dc.w $3c00
dc.w $6600
dc.w $6600
dc.w $3c00
dc.w $6600
dc.w $6600
dc.w $3c00
dc.w $0000
; 9
dc.w $3c00
dc.w $6600
dc.w $6600
dc.w $3e00
dc.w $0600
dc.w $0c00
dc.w $3800
dc.w $0000
;==============================================================================
; SOUND DATA (must be in Chip RAM for Paula DMA)
;==============================================================================
even
sound_hop:
dc.b $7f,$7f,$7f,$7f,$7f,$7f,$7f,$7f
dc.b $80,$80,$80,$80,$80,$80,$80,$80
dc.b $7f,$7f,$7f,$7f,$7f,$7f,$7f,$7f
dc.b $80,$80,$80,$80,$80,$80,$80,$80
HOP_LEN equ *-sound_hop
sound_death:
dc.b $7f,$7f,$7f,$7f,$80,$80,$80,$80
dc.b $7f,$7f,$7f,$7f,$80,$80,$80,$80
dc.b $7f,$7f,$7f,$7f,$7f,$80,$80,$80,$80,$80
dc.b $7f,$7f,$7f,$7f,$7f,$7f,$80,$80,$80,$80,$80,$80
dc.b $7f,$7f,$7f,$7f,$7f,$7f,$7f,$7f
dc.b $80,$80,$80,$80,$80,$80,$80,$80
DEATH_LEN equ *-sound_death
sound_home:
dc.b $7f,$80,$7f,$80,$7f,$80,$7f,$80
dc.b $7f,$80,$7f,$80,$7f,$80,$7f,$80
dc.b $7f,$7f,$80,$80,$7f,$7f,$80,$80
dc.b $7f,$7f,$80,$80,$7f,$7f,$80,$80
dc.b $7f,$7f,$7f,$80,$80,$80,$7f,$7f,$7f,$80,$80,$80
dc.b $00,$00,$00,$00
HOME_LEN equ *-sound_home
;==============================================================================
; SCREEN BUFFER
;==============================================================================
section chipbss,bss_c
even
screen_plane:
ds.b PLANE_SIZE
Build It
vasmm68k_mot -Fhunkexe -kick1hunks -o signal signal.asmWhat’s Next
The game has urgency, but every level plays the same. In Unit 14, we’ll add level progression—faster cars, tighter gaps, increasing challenge.
What Changed
Unit 12 → Unit 13
+100-5
| 1 | 1 | ;============================================================================== | |
| 2 | 2 | ; SIGNAL - A Frogger-style game for the Commodore Amiga | |
| 3 | - | ; Unit 12: Score Display | |
| 3 | + | ; Unit 13: Timer | |
| 4 | 4 | ; | |
| 5 | - | ; Tracking points internally is useless if players can't see them. This unit | |
| 6 | - | ; adds score display using bitmap digits. We convert the binary score to | |
| 7 | - | ; decimal and draw each digit using the Blitter. | |
| 5 | + | ; Time pressure creates urgency. This unit adds a 60-second countdown timer. | |
| 6 | + | ; Run out of time and you die. Reach home faster to earn bonus points. | |
| 8 | 7 | ;============================================================================== | |
| 9 | 8 | | |
| 10 | 9 | ;============================================================================== | |
| ... | |||
| 65 | 64 | SCORE_Y equ 236 ; Pixel Y position (grid row 12, in start zone) | |
| 66 | 65 | DIGIT_H equ 8 ; 8 pixels tall | |
| 67 | 66 | NUM_DIGITS equ 6 ; Display 6 digits (up to 999,999) | |
| 67 | + | | |
| 68 | + | ; Timer constants | |
| 69 | + | TIMER_START equ 3000 ; 60 seconds at 50Hz PAL (60 * 50) | |
| 70 | + | TIMER_X equ 56 ; Pixel X position for timer (left side) | |
| 71 | + | TIMER_Y equ 236 ; Same row as score | |
| 72 | + | TIMER_DIGITS equ 2 ; Display 2 digits (00-60) | |
| 68 | 73 | | |
| 69 | 74 | ; Audio constants | |
| 70 | 75 | SND_HOP equ 0 | |
| ... | |||
| 184 | 189 | | |
| 185 | 190 | move.w #$87e1,DMACON(a5) | |
| 186 | 191 | | |
| 187 | - | ; Display score after all DMA enabled | |
| 192 | + | ; Display score and timer after all DMA enabled | |
| 188 | 193 | bsr display_score | |
| 194 | + | bsr display_timer | |
| 189 | 195 | | |
| 190 | 196 | ;============================================================================== | |
| 191 | 197 | ; MAIN LOOP | |
| ... | |||
| 199 | 205 | | |
| 200 | 206 | bsr update_frog | |
| 201 | 207 | bsr update_sprite | |
| 208 | + | | |
| 209 | + | ; Update timer (only when not dying) | |
| 210 | + | cmp.w #STATE_DYING,frog_state | |
| 211 | + | beq.s .skip_timer | |
| 212 | + | bsr update_timer | |
| 213 | + | .skip_timer: | |
| 202 | 214 | | |
| 203 | 215 | bsr erase_all_cars | |
| 204 | 216 | bsr move_all_cars | |
| ... | |||
| 221 | 233 | bsr init_game | |
| 222 | 234 | bsr update_life_display | |
| 223 | 235 | bsr display_score | |
| 236 | + | bsr display_timer | |
| 224 | 237 | bsr clear_screen | |
| 225 | 238 | | |
| 226 | 239 | bra mainloop | |
| ... | |||
| 271 | 284 | dbf d3,.copy_row | |
| 272 | 285 | | |
| 273 | 286 | addq.l #1,a2 ; Move right by 1 byte (8 pixels) | |
| 287 | + | dbf d4,.draw_digit | |
| 288 | + | | |
| 289 | + | movem.l (sp)+,d0-d4/a0-a3 | |
| 290 | + | rts | |
| 291 | + | | |
| 292 | + | ;============================================================================== | |
| 293 | + | ; TIMER ROUTINES | |
| 294 | + | ;============================================================================== | |
| 295 | + | | |
| 296 | + | ;------------------------------------------------------------------------------ | |
| 297 | + | ; UPDATE_TIMER - Decrement timer and check for timeout | |
| 298 | + | ;------------------------------------------------------------------------------ | |
| 299 | + | update_timer: | |
| 300 | + | subq.w #1,timer | |
| 301 | + | bgt.s .not_timeout | |
| 302 | + | | |
| 303 | + | ; Timer reached zero - death! | |
| 304 | + | bsr trigger_death | |
| 305 | + | rts | |
| 306 | + | | |
| 307 | + | .not_timeout: | |
| 308 | + | ; Display timer every frame | |
| 309 | + | bsr display_timer | |
| 310 | + | rts | |
| 311 | + | | |
| 312 | + | ;------------------------------------------------------------------------------ | |
| 313 | + | ; DISPLAY_TIMER - Show remaining seconds on screen | |
| 314 | + | ;------------------------------------------------------------------------------ | |
| 315 | + | display_timer: | |
| 316 | + | movem.l d0-d4/a0-a3,-(sp) | |
| 317 | + | | |
| 318 | + | ; Convert timer frames to seconds (timer / 50) | |
| 319 | + | move.w timer(pc),d0 | |
| 320 | + | ext.l d0 | |
| 321 | + | divu #50,d0 ; d0 = seconds remaining | |
| 322 | + | | |
| 323 | + | ; Convert to 2 decimal digits | |
| 324 | + | lea timer_digits+4,a0 ; Point past end of buffer | |
| 325 | + | moveq #1,d4 ; 2 digits | |
| 326 | + | .convert: | |
| 327 | + | divu #10,d0 | |
| 328 | + | swap d0 | |
| 329 | + | move.w d0,-(a0) | |
| 330 | + | clr.w d0 | |
| 331 | + | swap d0 | |
| 332 | + | dbf d4,.convert | |
| 333 | + | | |
| 334 | + | ; Draw 2 digits using CPU byte copies | |
| 335 | + | lea timer_digits,a1 | |
| 336 | + | lea screen_plane,a2 | |
| 337 | + | add.l #TIMER_Y*SCREEN_W+TIMER_X/8,a2 | |
| 338 | + | | |
| 339 | + | moveq #1,d4 ; 2 digits | |
| 340 | + | .draw_digit: | |
| 341 | + | move.w (a1)+,d0 | |
| 342 | + | lsl.w #4,d0 ; *16 for font offset | |
| 343 | + | lea digit_font,a0 | |
| 344 | + | add.w d0,a0 | |
| 345 | + | | |
| 346 | + | move.l a2,a3 | |
| 347 | + | moveq #7,d3 ; 8 rows | |
| 348 | + | .copy_row: | |
| 349 | + | move.b (a0),(a3) | |
| 350 | + | addq.l #2,a0 | |
| 351 | + | lea SCREEN_W(a3),a3 | |
| 352 | + | dbf d3,.copy_row | |
| 353 | + | | |
| 354 | + | addq.l #1,a2 ; Next digit position | |
| 274 | 355 | dbf d4,.draw_digit | |
| 275 | 356 | | |
| 276 | 357 | movem.l (sp)+,d0-d4/a0-a3 | |
| ... | |||
| 338 | 419 | init_game: | |
| 339 | 420 | move.w #START_LIVES,lives | |
| 340 | 421 | clr.l score | |
| 422 | + | move.w #TIMER_START,timer ; Reset timer | |
| 341 | 423 | | |
| 342 | 424 | lea home_filled,a0 | |
| 343 | 425 | moveq #NUM_HOMES-1,d0 | |
| ... | |||
| 405 | 487 | | |
| 406 | 488 | move.w #1,0(a0,d1.w) | |
| 407 | 489 | add.l #POINTS_PER_HOME,score | |
| 490 | + | | |
| 491 | + | ; Time bonus: remaining seconds * 2 points | |
| 492 | + | move.w timer(pc),d0 | |
| 493 | + | ext.l d0 | |
| 494 | + | divu #50,d0 ; Convert frames to seconds | |
| 495 | + | and.l #$ffff,d0 ; Keep only quotient | |
| 496 | + | add.l d0,d0 ; *2 for bonus | |
| 497 | + | add.l d0,score ; Add time bonus | |
| 408 | 498 | | |
| 409 | 499 | move.w #SND_HOME,d0 | |
| 410 | 500 | bsr play_sound | |
| ... | |||
| 624 | 714 | clr.w frog_anim_frame | |
| 625 | 715 | clr.w joy_prev | |
| 626 | 716 | move.w #COLOUR_BLACK,flash_colour | |
| 717 | + | move.w #TIMER_START,timer ; Reset timer for new attempt | |
| 627 | 718 | bsr grid_to_pixels | |
| 628 | 719 | rts | |
| 629 | 720 | | |
| ... | |||
| 939 | 1030 | | |
| 940 | 1031 | lives: dc.w 3 | |
| 941 | 1032 | score: dc.l 0 | |
| 1033 | + | timer: dc.w 3000 ; Countdown timer in frames | |
| 942 | 1034 | | |
| 943 | 1035 | home_filled: dc.w 0,0,0,0,0 | |
| 944 | 1036 | | |
| 945 | 1037 | ; Buffer for score digits | |
| 946 | 1038 | score_digits: dc.w 0,0,0,0,0,0 | |
| 1039 | + | | |
| 1040 | + | ; Buffer for timer digits (2 digits for seconds) | |
| 1041 | + | timer_digits: dc.w 0,0 | |
| 947 | 1042 | | |
| 948 | 1043 | car_data: | |
| 949 | 1044 | dc.w 0,7,1,0 |