Game 1 Unit 8 of 64 1 hr learning time
Health System
A health meter that grows on hits and shrinks on misses. The game can be lost.
13% of SID Symphony
A game without stakes is just practice. Now the game can be lost.
This unit adds a health system. Health starts at half-full. Perfect hits restore 4 points. Good hits restore 2 points. Misses cost 8 points. When health reaches zero, the game ends. Success requires sustained performance.
Run It
Assemble and run:
acme -f cbm -o symphony.prg symphony.asm
The health bar displays at the bottom. Watch it grow as you hit notes and shrink when you miss. Let too many notes through and the game ends with “GAME OVER” in red.
Health Logic
Health is a single byte ranging from 0 to 64. Changes are clamped - you can’t go below 0 or above 64:
; ----------------------------------------------------------------------------
; Health Settings
; ----------------------------------------------------------------------------
HEALTH_MAX = 64 ; Maximum health
HEALTH_START = 32 ; Starting health (half)
HEALTH_PERFECT = 4 ; Health gained on perfect hit
HEALTH_GOOD = 2 ; Health gained on good hit
HEALTH_MISS = 8 ; Health lost on miss
; ----------------------------------------------------------------------------
; Initialize Health
; ----------------------------------------------------------------------------
init_health:
lda #HEALTH_START
sta health
jsr display_health
rts
; ----------------------------------------------------------------------------
; Decrease Health - Subtract HEALTH_MISS, clamp at 0
; ----------------------------------------------------------------------------
decrease_health:
lda health
sec
sbc #HEALTH_MISS
bcc health_zero ; Underflow - set to 0
sta health
jsr display_health
jsr check_game_over
rts
health_zero:
lda #0
sta health
jsr display_health
jsr check_game_over
rts
; ----------------------------------------------------------------------------
; Increase Health - Add amount, clamp at HEALTH_MAX
; Input: A = amount to add
; ----------------------------------------------------------------------------
increase_health:
clc
adc health
cmp #HEALTH_MAX
bcc health_ok
lda #HEALTH_MAX ; Clamp to max
health_ok:
sta health
jsr display_health
rts
The decrease_health routine uses the carry flag to detect underflow. After SBC, if carry is clear, the result went negative. Rather than storing a garbage value, we clamp to zero. The increase_health routine works similarly - compare against the maximum and clamp if exceeded.
The Health Bar
A visual bar makes health tangible. Eight characters represent 64 health points - each character shows 8 points:
; ----------------------------------------------------------------------------
; Display Health - 8 character bar
; ----------------------------------------------------------------------------
display_health:
; Health ranges 0-64, displayed as 8 characters
; Each character represents 8 health points
lda health
lsr ; Divide by 8
lsr
lsr
sta temp_health ; Full bars to draw
; Draw full bars
ldx #0
lda temp_health
beq draw_empty_bars
draw_full_bars:
lda #CHAR_BAR_FULL
sta SCREEN + (HEALTH_ROW * 40) + 16,x
lda #HEALTH_COL
sta COLRAM + (HEALTH_ROW * 40) + 16,x
inx
cpx temp_health
bne draw_full_bars
; Draw empty bars for remainder
draw_empty_bars:
cpx #8
beq health_done
lda #CHAR_BAR_EMPTY
sta SCREEN + (HEALTH_ROW * 40) + 16,x
lda #11 ; Dark grey
sta COLRAM + (HEALTH_ROW * 40) + 16,x
inx
jmp draw_empty_bars
health_done:
rts
The LSR instructions divide health by 8 (three right shifts = divide by 2³ = divide by 8). This gives the number of full bar characters to draw. The remaining positions get empty bar characters.
Custom Bar Characters
Two new custom characters create the health bar:
; Health bar full - solid block
lda #%11111111
sta CHARSET + (CHAR_BAR_FULL * 8) + 0
; ... (all 8 rows solid)
; Health bar empty - outline
lda #%11111111
sta CHARSET + (CHAR_BAR_EMPTY * 8) + 0
lda #%10000001
sta CHARSET + (CHAR_BAR_EMPTY * 8) + 1
; ... (middle rows outline only)The full bar is a solid block. The empty bar shows just the outline - indicating capacity without filling it. The contrast makes current health immediately clear.
Game Over
When health hits zero, the game freezes:
; ----------------------------------------------------------------------------
; Check Game Over
; ----------------------------------------------------------------------------
check_game_over:
lda health
bne not_game_over
; Game over!
lda #1
sta game_over
; Display game over message
jsr show_game_over
not_game_over:
rts
; ----------------------------------------------------------------------------
; Show Game Over
; ----------------------------------------------------------------------------
show_game_over:
; Display "GAME OVER" in centre of screen
ldx #0
game_over_loop:
lda game_over_text,x
beq game_over_done
sta SCREEN + (12 * 40) + 15,x
lda #2 ; Red
sta COLRAM + (12 * 40) + 15,x
inx
jmp game_over_loop
game_over_done:
; Flash border red
lda #2
sta BORDER
rts
game_over_text:
!scr "game over"
!byte 0
The game_over variable acts as a flag. Once set, the main loop skips all game logic - notes stop spawning, keys stop responding. The player sees “GAME OVER” in red and must restart.
Hooking Into Existing Code
The health system integrates with existing routines. In award_points:
; Increase health for perfect hit
lda #HEALTH_PERFECT
jsr increase_healthIn handle_miss:
; Decrease health
jsr decrease_healthSmall additions to existing code. The routines we wrote handle all the complexity.
The Complete Code
; ============================================================================
; SID SYMPHONY - Unit 8: Health System
; ============================================================================
; A health meter that grows on hits and shrinks on misses. The game can be
; lost. Stakes make success meaningful.
;
; Controls: Z = Track 1 (high), X = Track 2 (mid), C = Track 3 (low)
; ============================================================================
; ============================================================================
; CUSTOMISATION SECTION
; ============================================================================
; SID Voice Settings
VOICE1_WAVE = $21 ; Sawtooth
VOICE2_WAVE = $41 ; Pulse
VOICE3_WAVE = $11 ; Triangle
VOICE1_FREQ = $1C ; High pitch
VOICE2_FREQ = $0E ; Mid pitch
VOICE3_FREQ = $07 ; Low pitch
VOICE_AD = $09 ; Attack=0, Decay=9
VOICE_SR = $00 ; Sustain=0, Release=0
PULSE_WIDTH = $08 ; 50% duty cycle
; Miss sound settings
MISS_FREQ = $08 ; Low rumble
MISS_WAVE = $81 ; Noise waveform
MISS_AD = $00 ; Instant attack, no decay
MISS_SR = $90 ; High sustain, fast release
; Visual Settings
BORDER_COL = 0 ; Black border
BG_COL = 0 ; Black background
TRACK1_NOTE_COL = 10 ; Light red
TRACK2_NOTE_COL = 13 ; Light green
TRACK3_NOTE_COL = 14 ; Light blue
TRACK_LINE_COL = 11 ; Dark grey
HIT_ZONE_COL = 7 ; Yellow
FLASH1_COL = 2 ; Red
FLASH2_COL = 5 ; Green
FLASH3_COL = 6 ; Blue
HIT_COL = 1 ; White - flash on successful hit
PERFECT_COL = 1 ; White - perfect hit border flash
GOOD_COL = 7 ; Yellow - good hit border flash
MISS_COL = 2 ; Red - miss border flash
HEALTH_COL = 5 ; Green for health bar
; ============================================================================
; SCORING SETTINGS
; ============================================================================
PERFECT_SCORE = 100
GOOD_SCORE = 50
; ============================================================================
; HEALTH SETTINGS
; ============================================================================
HEALTH_MAX = 64 ; Maximum health
HEALTH_START = 32 ; Starting health (half)
HEALTH_PERFECT = 4 ; Health gained on perfect hit
HEALTH_GOOD = 2 ; Health gained on good hit
HEALTH_MISS = 8 ; Health lost on miss
; ============================================================================
; HIT DETECTION SETTINGS
; ============================================================================
HIT_ZONE_MIN = 2
HIT_ZONE_MAX = 5
HIT_ZONE_CENTRE = 3
; ============================================================================
; MEMORY MAP
; ============================================================================
SCREEN = $0400
COLRAM = $D800
BORDER = $D020
BGCOL = $D021
CHARPTR = $D018
CHARSET = $3000
; SID registers
SID = $D400
SID_V1_FREQ_LO = $D400
SID_V1_FREQ_HI = $D401
SID_V1_PWHI = $D403
SID_V1_CTRL = $D404
SID_V1_AD = $D405
SID_V1_SR = $D406
SID_V2_FREQ_LO = $D407
SID_V2_FREQ_HI = $D408
SID_V2_PWHI = $D40A
SID_V2_CTRL = $D40B
SID_V2_AD = $D40C
SID_V2_SR = $D40D
SID_V3_FREQ_LO = $D40E
SID_V3_FREQ_HI = $D40F
SID_V3_PWHI = $D411
SID_V3_CTRL = $D412
SID_V3_AD = $D413
SID_V3_SR = $D414
SID_VOLUME = $D418
; CIA keyboard
CIA1_PRA = $DC00
CIA1_PRB = $DC01
; Track positions
TRACK1_ROW = 8
TRACK2_ROW = 12
TRACK3_ROW = 16
; Health bar position
HEALTH_ROW = 23
; Hit zone
HIT_ZONE_COLUMN = 3
; Custom character codes
CHAR_NOTE = 128
CHAR_TRACK = 129
CHAR_HITZONE = 130
CHAR_SPACE = 32
CHAR_BAR_FULL = 131
CHAR_BAR_EMPTY = 132
; Note settings
MAX_NOTES = 8
NOTE_SPAWN_COL = 37
; Timing
FRAMES_PER_BEAT = 25
; Zero page
ZP_PTR = $FB
ZP_PTR_HI = $FC
; Variables
frame_count = $02
beat_count = $03
song_pos = $04
song_pos_hi = $05
temp_track = $06
key_pressed = $07
hit_quality = $08
border_flash = $09
miss_track = $0A
game_over = $0B ; Non-zero when game ended
; ----------------------------------------------------------------------------
; BASIC Stub
; ----------------------------------------------------------------------------
* = $0801
!byte $0C, $08
!byte $0A, $00
!byte $9E
!text "2064"
!byte $00
!byte $00, $00
; ----------------------------------------------------------------------------
; Main Program
; ----------------------------------------------------------------------------
* = $0810
start:
jsr copy_charset
jsr init_screen
jsr init_sid
jsr init_notes
jsr init_score
jsr init_health
lda #<song_data
sta song_pos
lda #>song_data
sta song_pos_hi
lda #0
sta frame_count
sta beat_count
sta border_flash
sta game_over
main_loop:
lda #$FF
wait_raster:
cmp $D012
bne wait_raster
; Check if game is over
lda game_over
bne main_loop ; Freeze if game over
inc frame_count
lda frame_count
cmp #FRAMES_PER_BEAT
bcc no_new_beat
lda #0
sta frame_count
jsr check_spawn_note
inc beat_count
no_new_beat:
jsr update_notes
jsr reset_track_colours
jsr update_border_flash
jsr check_keys
jmp main_loop
; ----------------------------------------------------------------------------
; Copy Character Set from ROM to RAM
; ----------------------------------------------------------------------------
copy_charset:
sei
lda $01
pha
and #$FB
sta $01
ldx #0
copy_loop:
lda $D000,x
sta CHARSET,x
lda $D100,x
sta CHARSET+$100,x
lda $D200,x
sta CHARSET+$200,x
lda $D300,x
sta CHARSET+$300,x
lda $D400,x
sta CHARSET+$400,x
lda $D500,x
sta CHARSET+$500,x
lda $D600,x
sta CHARSET+$600,x
lda $D700,x
sta CHARSET+$700,x
inx
bne copy_loop
pla
sta $01
cli
jsr define_custom_chars
lda #$1C
sta CHARPTR
rts
; ----------------------------------------------------------------------------
; Define Custom Characters
; ----------------------------------------------------------------------------
define_custom_chars:
; Note character - diamond shape
lda #%00000110
sta CHARSET + (CHAR_NOTE * 8) + 0
lda #%00011110
sta CHARSET + (CHAR_NOTE * 8) + 1
lda #%01111110
sta CHARSET + (CHAR_NOTE * 8) + 2
lda #%11111110
sta CHARSET + (CHAR_NOTE * 8) + 3
lda #%11111110
sta CHARSET + (CHAR_NOTE * 8) + 4
lda #%01111110
sta CHARSET + (CHAR_NOTE * 8) + 5
lda #%00011110
sta CHARSET + (CHAR_NOTE * 8) + 6
lda #%00000110
sta CHARSET + (CHAR_NOTE * 8) + 7
; Track character - horizontal line
lda #%00000000
sta CHARSET + (CHAR_TRACK * 8) + 0
lda #%00000000
sta CHARSET + (CHAR_TRACK * 8) + 1
lda #%00000000
sta CHARSET + (CHAR_TRACK * 8) + 2
lda #%11111111
sta CHARSET + (CHAR_TRACK * 8) + 3
lda #%11111111
sta CHARSET + (CHAR_TRACK * 8) + 4
lda #%00000000
sta CHARSET + (CHAR_TRACK * 8) + 5
lda #%00000000
sta CHARSET + (CHAR_TRACK * 8) + 6
lda #%00000000
sta CHARSET + (CHAR_TRACK * 8) + 7
; Hit zone character - vertical bars
lda #%01100110
sta CHARSET + (CHAR_HITZONE * 8) + 0
sta CHARSET + (CHAR_HITZONE * 8) + 1
sta CHARSET + (CHAR_HITZONE * 8) + 2
sta CHARSET + (CHAR_HITZONE * 8) + 3
sta CHARSET + (CHAR_HITZONE * 8) + 4
sta CHARSET + (CHAR_HITZONE * 8) + 5
sta CHARSET + (CHAR_HITZONE * 8) + 6
sta CHARSET + (CHAR_HITZONE * 8) + 7
; Health bar full - solid block
lda #%11111111
sta CHARSET + (CHAR_BAR_FULL * 8) + 0
sta CHARSET + (CHAR_BAR_FULL * 8) + 1
sta CHARSET + (CHAR_BAR_FULL * 8) + 2
sta CHARSET + (CHAR_BAR_FULL * 8) + 3
sta CHARSET + (CHAR_BAR_FULL * 8) + 4
sta CHARSET + (CHAR_BAR_FULL * 8) + 5
sta CHARSET + (CHAR_BAR_FULL * 8) + 6
sta CHARSET + (CHAR_BAR_FULL * 8) + 7
; Health bar empty - outline
lda #%11111111
sta CHARSET + (CHAR_BAR_EMPTY * 8) + 0
lda #%10000001
sta CHARSET + (CHAR_BAR_EMPTY * 8) + 1
sta CHARSET + (CHAR_BAR_EMPTY * 8) + 2
sta CHARSET + (CHAR_BAR_EMPTY * 8) + 3
sta CHARSET + (CHAR_BAR_EMPTY * 8) + 4
sta CHARSET + (CHAR_BAR_EMPTY * 8) + 5
sta CHARSET + (CHAR_BAR_EMPTY * 8) + 6
lda #%11111111
sta CHARSET + (CHAR_BAR_EMPTY * 8) + 7
rts
; ----------------------------------------------------------------------------
; Initialize Health
; ----------------------------------------------------------------------------
init_health:
lda #HEALTH_START
sta health
jsr display_health
rts
; ----------------------------------------------------------------------------
; Initialize Score
; ----------------------------------------------------------------------------
init_score:
lda #0
sta score_lo
sta score_hi
sta miss_count
jsr display_score
jsr display_misses
rts
; ----------------------------------------------------------------------------
; Initialize Notes
; ----------------------------------------------------------------------------
init_notes:
ldx #MAX_NOTES-1
lda #0
init_notes_loop:
sta note_track,x
sta note_col,x
dex
bpl init_notes_loop
rts
; ----------------------------------------------------------------------------
; Check Spawn Note
; ----------------------------------------------------------------------------
check_spawn_note:
ldy #0
spawn_check_loop:
lda (song_pos),y
cmp #$FF
beq spawn_restart_song
cmp beat_count
beq spawn_match
bcs spawn_done
jmp spawn_advance
spawn_match:
iny
lda (song_pos),y
jsr spawn_note
dey
spawn_advance:
lda song_pos
clc
adc #2
sta song_pos
lda song_pos_hi
adc #0
sta song_pos_hi
jmp spawn_check_loop
spawn_done:
rts
spawn_restart_song:
lda #<song_data
sta song_pos
lda #>song_data
sta song_pos_hi
lda #0
sta beat_count
rts
; ----------------------------------------------------------------------------
; Spawn Note
; ----------------------------------------------------------------------------
spawn_note:
sta temp_track
ldx #0
spawn_find_slot:
lda note_track,x
beq spawn_found_slot
inx
cpx #MAX_NOTES
bne spawn_find_slot
rts
spawn_found_slot:
lda temp_track
sta note_track,x
lda #NOTE_SPAWN_COL
sta note_col,x
jsr draw_note
rts
; ----------------------------------------------------------------------------
; Update Notes
; ----------------------------------------------------------------------------
update_notes:
ldx #0
update_loop:
lda note_track,x
beq update_next
jsr erase_note
dec note_col,x
lda note_col,x
cmp #1
bcc update_miss
jsr draw_note
jmp update_next
update_miss:
lda note_track,x
sta miss_track
lda #0
sta note_track,x
jsr handle_miss
update_next:
inx
cpx #MAX_NOTES
bne update_loop
rts
; ----------------------------------------------------------------------------
; Handle Miss
; ----------------------------------------------------------------------------
handle_miss:
inc miss_count
jsr play_miss_sound
lda #MISS_COL
sta BORDER
lda #8
sta border_flash
jsr display_misses
; Decrease health
jsr decrease_health
rts
; ----------------------------------------------------------------------------
; Decrease Health - Subtract HEALTH_MISS, clamp at 0
; ----------------------------------------------------------------------------
decrease_health:
lda health
sec
sbc #HEALTH_MISS
bcc health_zero ; Underflow - set to 0
sta health
jsr display_health
jsr check_game_over
rts
health_zero:
lda #0
sta health
jsr display_health
jsr check_game_over
rts
; ----------------------------------------------------------------------------
; Increase Health - Add amount, clamp at HEALTH_MAX
; Input: A = amount to add
; ----------------------------------------------------------------------------
increase_health:
clc
adc health
cmp #HEALTH_MAX
bcc health_ok
lda #HEALTH_MAX ; Clamp to max
health_ok:
sta health
jsr display_health
rts
; ----------------------------------------------------------------------------
; Check Game Over
; ----------------------------------------------------------------------------
check_game_over:
lda health
bne not_game_over
; Game over!
lda #1
sta game_over
; Display game over message
jsr show_game_over
not_game_over:
rts
; ----------------------------------------------------------------------------
; Show Game Over
; ----------------------------------------------------------------------------
show_game_over:
; Display "GAME OVER" in centre of screen
ldx #0
game_over_loop:
lda game_over_text,x
beq game_over_done
sta SCREEN + (12 * 40) + 15,x
lda #2 ; Red
sta COLRAM + (12 * 40) + 15,x
inx
jmp game_over_loop
game_over_done:
; Flash border red
lda #2
sta BORDER
rts
game_over_text:
!scr "game over"
!byte 0
; ----------------------------------------------------------------------------
; Display Health - 8 character bar
; ----------------------------------------------------------------------------
display_health:
; Health ranges 0-64, displayed as 8 characters
; Each character represents 8 health points
lda health
lsr ; Divide by 8
lsr
lsr
sta temp_health ; Full bars to draw
; Draw full bars
ldx #0
lda temp_health
beq draw_empty_bars
draw_full_bars:
lda #CHAR_BAR_FULL
sta SCREEN + (HEALTH_ROW * 40) + 16,x
lda #HEALTH_COL
sta COLRAM + (HEALTH_ROW * 40) + 16,x
inx
cpx temp_health
bne draw_full_bars
; Draw empty bars for remainder
draw_empty_bars:
cpx #8
beq health_done
lda #CHAR_BAR_EMPTY
sta SCREEN + (HEALTH_ROW * 40) + 16,x
lda #11 ; Dark grey
sta COLRAM + (HEALTH_ROW * 40) + 16,x
inx
jmp draw_empty_bars
health_done:
rts
temp_health: !byte 0
; ----------------------------------------------------------------------------
; Play Miss Sound
; ----------------------------------------------------------------------------
play_miss_sound:
lda #0
sta SID_V3_FREQ_LO
lda #MISS_FREQ
sta SID_V3_FREQ_HI
lda #MISS_AD
sta SID_V3_AD
lda #MISS_SR
sta SID_V3_SR
lda #MISS_WAVE
ora #$01
sta SID_V3_CTRL
rts
; ----------------------------------------------------------------------------
; Draw Note
; ----------------------------------------------------------------------------
draw_note:
lda note_track,x
cmp #1
beq draw_note_t1
cmp #2
beq draw_note_t2
cmp #3
beq draw_note_t3
rts
draw_note_t1:
lda note_col,x
clc
adc #<(SCREEN + TRACK1_ROW * 40)
sta ZP_PTR
lda #>(SCREEN + TRACK1_ROW * 40)
adc #0
sta ZP_PTR_HI
ldy #0
lda #CHAR_NOTE
sta (ZP_PTR),y
lda note_col,x
clc
adc #<(COLRAM + TRACK1_ROW * 40)
sta ZP_PTR
lda #>(COLRAM + TRACK1_ROW * 40)
adc #0
sta ZP_PTR_HI
lda #TRACK1_NOTE_COL
sta (ZP_PTR),y
rts
draw_note_t2:
lda note_col,x
clc
adc #<(SCREEN + TRACK2_ROW * 40)
sta ZP_PTR
lda #>(SCREEN + TRACK2_ROW * 40)
adc #0
sta ZP_PTR_HI
ldy #0
lda #CHAR_NOTE
sta (ZP_PTR),y
lda note_col,x
clc
adc #<(COLRAM + TRACK2_ROW * 40)
sta ZP_PTR
lda #>(COLRAM + TRACK2_ROW * 40)
adc #0
sta ZP_PTR_HI
lda #TRACK2_NOTE_COL
sta (ZP_PTR),y
rts
draw_note_t3:
lda note_col,x
clc
adc #<(SCREEN + TRACK3_ROW * 40)
sta ZP_PTR
lda #>(SCREEN + TRACK3_ROW * 40)
adc #0
sta ZP_PTR_HI
ldy #0
lda #CHAR_NOTE
sta (ZP_PTR),y
lda note_col,x
clc
adc #<(COLRAM + TRACK3_ROW * 40)
sta ZP_PTR
lda #>(COLRAM + TRACK3_ROW * 40)
adc #0
sta ZP_PTR_HI
lda #TRACK3_NOTE_COL
sta (ZP_PTR),y
rts
; ----------------------------------------------------------------------------
; Erase Note
; ----------------------------------------------------------------------------
erase_note:
lda note_track,x
cmp #1
beq erase_note_t1
cmp #2
beq erase_note_t2
cmp #3
beq erase_note_t3
rts
erase_note_t1:
lda note_col,x
clc
adc #<(SCREEN + TRACK1_ROW * 40)
sta ZP_PTR
lda #>(SCREEN + TRACK1_ROW * 40)
adc #0
sta ZP_PTR_HI
ldy #0
lda #CHAR_TRACK
sta (ZP_PTR),y
lda note_col,x
clc
adc #<(COLRAM + TRACK1_ROW * 40)
sta ZP_PTR
lda #>(COLRAM + TRACK1_ROW * 40)
adc #0
sta ZP_PTR_HI
lda #TRACK_LINE_COL
sta (ZP_PTR),y
rts
erase_note_t2:
lda note_col,x
clc
adc #<(SCREEN + TRACK2_ROW * 40)
sta ZP_PTR
lda #>(SCREEN + TRACK2_ROW * 40)
adc #0
sta ZP_PTR_HI
ldy #0
lda #CHAR_TRACK
sta (ZP_PTR),y
lda note_col,x
clc
adc #<(COLRAM + TRACK2_ROW * 40)
sta ZP_PTR
lda #>(COLRAM + TRACK2_ROW * 40)
adc #0
sta ZP_PTR_HI
lda #TRACK_LINE_COL
sta (ZP_PTR),y
rts
erase_note_t3:
lda note_col,x
clc
adc #<(SCREEN + TRACK3_ROW * 40)
sta ZP_PTR
lda #>(SCREEN + TRACK3_ROW * 40)
adc #0
sta ZP_PTR_HI
ldy #0
lda #CHAR_TRACK
sta (ZP_PTR),y
lda note_col,x
clc
adc #<(COLRAM + TRACK3_ROW * 40)
sta ZP_PTR
lda #>(COLRAM + TRACK3_ROW * 40)
adc #0
sta ZP_PTR_HI
lda #TRACK_LINE_COL
sta (ZP_PTR),y
rts
; ----------------------------------------------------------------------------
; Initialize Screen
; ----------------------------------------------------------------------------
init_screen:
lda #BORDER_COL
sta BORDER
lda #BG_COL
sta BGCOL
ldx #0
lda #CHAR_SPACE
clr_screen:
sta SCREEN,x
sta SCREEN+$100,x
sta SCREEN+$200,x
sta SCREEN+$2E8,x
inx
bne clr_screen
ldx #0
lda #TRACK_LINE_COL
clr_colour:
sta COLRAM,x
sta COLRAM+$100,x
sta COLRAM+$200,x
sta COLRAM+$2E8,x
inx
bne clr_colour
jsr draw_tracks
jsr draw_hit_zones
jsr draw_labels
rts
; ----------------------------------------------------------------------------
; Draw Tracks
; ----------------------------------------------------------------------------
draw_tracks:
lda #CHAR_TRACK
ldx #0
draw_t1:
sta SCREEN + (TRACK1_ROW * 40),x
inx
cpx #38
bne draw_t1
lda #CHAR_TRACK
ldx #0
draw_t2:
sta SCREEN + (TRACK2_ROW * 40),x
inx
cpx #38
bne draw_t2
lda #CHAR_TRACK
ldx #0
draw_t3:
sta SCREEN + (TRACK3_ROW * 40),x
inx
cpx #38
bne draw_t3
rts
; ----------------------------------------------------------------------------
; Draw Hit Zones
; ----------------------------------------------------------------------------
draw_hit_zones:
lda #CHAR_HITZONE
sta SCREEN + ((TRACK1_ROW-2) * 40) + HIT_ZONE_COLUMN
sta SCREEN + ((TRACK1_ROW-1) * 40) + HIT_ZONE_COLUMN
sta SCREEN + (TRACK1_ROW * 40) + HIT_ZONE_COLUMN
sta SCREEN + ((TRACK1_ROW+1) * 40) + HIT_ZONE_COLUMN
sta SCREEN + ((TRACK2_ROW-1) * 40) + HIT_ZONE_COLUMN
sta SCREEN + (TRACK2_ROW * 40) + HIT_ZONE_COLUMN
sta SCREEN + ((TRACK2_ROW+1) * 40) + HIT_ZONE_COLUMN
sta SCREEN + ((TRACK3_ROW-1) * 40) + HIT_ZONE_COLUMN
sta SCREEN + (TRACK3_ROW * 40) + HIT_ZONE_COLUMN
sta SCREEN + ((TRACK3_ROW+1) * 40) + HIT_ZONE_COLUMN
sta SCREEN + ((TRACK3_ROW+2) * 40) + HIT_ZONE_COLUMN
lda #HIT_ZONE_COL
sta COLRAM + ((TRACK1_ROW-2) * 40) + HIT_ZONE_COLUMN
sta COLRAM + ((TRACK1_ROW-1) * 40) + HIT_ZONE_COLUMN
sta COLRAM + (TRACK1_ROW * 40) + HIT_ZONE_COLUMN
sta COLRAM + ((TRACK1_ROW+1) * 40) + HIT_ZONE_COLUMN
sta COLRAM + ((TRACK2_ROW-1) * 40) + HIT_ZONE_COLUMN
sta COLRAM + (TRACK2_ROW * 40) + HIT_ZONE_COLUMN
sta COLRAM + ((TRACK2_ROW+1) * 40) + HIT_ZONE_COLUMN
sta COLRAM + ((TRACK3_ROW-1) * 40) + HIT_ZONE_COLUMN
sta COLRAM + (TRACK3_ROW * 40) + HIT_ZONE_COLUMN
sta COLRAM + ((TRACK3_ROW+1) * 40) + HIT_ZONE_COLUMN
sta COLRAM + ((TRACK3_ROW+2) * 40) + HIT_ZONE_COLUMN
rts
; ----------------------------------------------------------------------------
; Draw Labels
; ----------------------------------------------------------------------------
draw_labels:
; Draw "SCORE:" label
ldx #0
draw_score_label:
lda score_label,x
beq draw_score_label_done
sta SCREEN + 1,x
lda #1
sta COLRAM + 1,x
inx
bne draw_score_label
draw_score_label_done:
; Draw "MISS:" label
ldx #0
draw_miss_label:
lda miss_label,x
beq draw_miss_label_done
sta SCREEN + 15,x
lda #2
sta COLRAM + 15,x
inx
bne draw_miss_label
draw_miss_label_done:
; Draw title
ldx #0
draw_title:
lda title_text,x
beq draw_title_done
sta SCREEN + 27,x
lda #1
sta COLRAM + 27,x
inx
bne draw_title
draw_title_done:
; Draw "HEALTH:" label
ldx #0
draw_health_label:
lda health_label,x
beq draw_health_label_done
sta SCREEN + (HEALTH_ROW * 40) + 8,x
lda #5 ; Green
sta COLRAM + (HEALTH_ROW * 40) + 8,x
inx
bne draw_health_label
draw_health_label_done:
; Track labels
lda #$1A ; Z
sta SCREEN + (TRACK1_ROW * 40)
lda #TRACK1_NOTE_COL
sta COLRAM + (TRACK1_ROW * 40)
lda #$18 ; X
sta SCREEN + (TRACK2_ROW * 40)
lda #TRACK2_NOTE_COL
sta COLRAM + (TRACK2_ROW * 40)
lda #$03 ; C
sta SCREEN + (TRACK3_ROW * 40)
lda #TRACK3_NOTE_COL
sta COLRAM + (TRACK3_ROW * 40)
rts
score_label:
!scr "score:"
!byte 0
miss_label:
!scr "miss:"
!byte 0
title_text:
!scr "sid symphony"
!byte 0
health_label:
!scr "health:"
!byte 0
; ----------------------------------------------------------------------------
; Initialize SID
; ----------------------------------------------------------------------------
init_sid:
ldx #$18
lda #0
clear_sid:
sta SID,x
dex
bpl clear_sid
lda #$0F
sta SID_VOLUME
lda #$00
sta SID_V1_FREQ_LO
lda #VOICE1_FREQ
sta SID_V1_FREQ_HI
lda #PULSE_WIDTH
sta SID_V1_PWHI
lda #VOICE_AD
sta SID_V1_AD
lda #VOICE_SR
sta SID_V1_SR
lda #$00
sta SID_V2_FREQ_LO
lda #VOICE2_FREQ
sta SID_V2_FREQ_HI
lda #PULSE_WIDTH
sta SID_V2_PWHI
lda #VOICE_AD
sta SID_V2_AD
lda #VOICE_SR
sta SID_V2_SR
lda #$00
sta SID_V3_FREQ_LO
lda #VOICE3_FREQ
sta SID_V3_FREQ_HI
lda #PULSE_WIDTH
sta SID_V3_PWHI
lda #VOICE_AD
sta SID_V3_AD
lda #VOICE_SR
sta SID_V3_SR
rts
; ----------------------------------------------------------------------------
; Reset Track Colours
; ----------------------------------------------------------------------------
reset_track_colours:
ldx #0
lda #TRACK_LINE_COL
reset_t1:
sta COLRAM + (TRACK1_ROW * 40),x
inx
cpx #38
bne reset_t1
ldx #0
reset_t2:
sta COLRAM + (TRACK2_ROW * 40),x
inx
cpx #38
bne reset_t2
ldx #0
reset_t3:
sta COLRAM + (TRACK3_ROW * 40),x
inx
cpx #38
bne reset_t3
lda #TRACK1_NOTE_COL
sta COLRAM + (TRACK1_ROW * 40)
lda #TRACK2_NOTE_COL
sta COLRAM + (TRACK2_ROW * 40)
lda #TRACK3_NOTE_COL
sta COLRAM + (TRACK3_ROW * 40)
lda #HIT_ZONE_COL
sta COLRAM + (TRACK1_ROW * 40) + HIT_ZONE_COLUMN
sta COLRAM + (TRACK2_ROW * 40) + HIT_ZONE_COLUMN
sta COLRAM + (TRACK3_ROW * 40) + HIT_ZONE_COLUMN
jsr redraw_all_notes
rts
; ----------------------------------------------------------------------------
; Redraw All Notes
; ----------------------------------------------------------------------------
redraw_all_notes:
ldx #0
redraw_loop:
lda note_track,x
beq redraw_next
jsr draw_note
redraw_next:
inx
cpx #MAX_NOTES
bne redraw_loop
rts
; ----------------------------------------------------------------------------
; Update Border Flash
; ----------------------------------------------------------------------------
update_border_flash:
lda border_flash
beq flash_done
dec border_flash
bne flash_done
lda #BORDER_COL
sta BORDER
flash_done:
rts
; ----------------------------------------------------------------------------
; Check Keys
; ----------------------------------------------------------------------------
check_keys:
lda #$FD
sta CIA1_PRA
lda CIA1_PRB
and #$10
bne check_x_key
lda #1
sta key_pressed
jsr check_hit
bcc check_x_key
jsr play_voice1
jsr flash_track1_hit
jsr award_points
check_x_key:
lda #$FB
sta CIA1_PRA
lda CIA1_PRB
and #$80
bne check_c_key
lda #2
sta key_pressed
jsr check_hit
bcc check_c_key
jsr play_voice2
jsr flash_track2_hit
jsr award_points
check_c_key:
lda #$FB
sta CIA1_PRA
lda CIA1_PRB
and #$10
bne check_keys_done
lda #3
sta key_pressed
jsr check_hit
bcc check_keys_done
jsr play_voice3
jsr flash_track3_hit
jsr award_points
check_keys_done:
lda #$FF
sta CIA1_PRA
rts
; ----------------------------------------------------------------------------
; Check Hit
; ----------------------------------------------------------------------------
check_hit:
ldx #0
check_hit_loop:
lda note_track,x
beq check_hit_next
cmp key_pressed
bne check_hit_next
lda note_col,x
cmp #HIT_ZONE_MIN
bcc check_hit_next
cmp #HIT_ZONE_MAX+1
bcs check_hit_next
cmp #HIT_ZONE_CENTRE
bcc hit_good
cmp #HIT_ZONE_CENTRE+2
bcs hit_good
lda #2
sta hit_quality
jmp hit_found
hit_good:
lda #1
sta hit_quality
hit_found:
jsr erase_note
lda #0
sta note_track,x
sec
rts
check_hit_next:
inx
cpx #MAX_NOTES
bne check_hit_loop
lda #0
sta hit_quality
clc
rts
; ----------------------------------------------------------------------------
; Award Points
; ----------------------------------------------------------------------------
award_points:
lda hit_quality
cmp #2
beq award_perfect
lda score_lo
clc
adc #GOOD_SCORE
sta score_lo
lda score_hi
adc #0
sta score_hi
lda #GOOD_COL
sta BORDER
lda #4
sta border_flash
; Increase health for good hit
lda #HEALTH_GOOD
jsr increase_health
jmp award_done
award_perfect:
lda score_lo
clc
adc #PERFECT_SCORE
sta score_lo
lda score_hi
adc #0
sta score_hi
lda #PERFECT_COL
sta BORDER
lda #6
sta border_flash
; Increase health for perfect hit
lda #HEALTH_PERFECT
jsr increase_health
award_done:
jsr display_score
rts
; ----------------------------------------------------------------------------
; Display Score
; ----------------------------------------------------------------------------
display_score:
lda score_lo
sta work_lo
lda score_hi
sta work_hi
ldx #0
div_10000:
lda work_lo
sec
sbc #<10000
tay
lda work_hi
sbc #>10000
bcc done_10000
sta work_hi
sty work_lo
inx
jmp div_10000
done_10000:
txa
ora #$30
sta SCREEN + 8
ldx #0
div_1000:
lda work_lo
sec
sbc #<1000
tay
lda work_hi
sbc #>1000
bcc done_1000
sta work_hi
sty work_lo
inx
jmp div_1000
done_1000:
txa
ora #$30
sta SCREEN + 9
ldx #0
div_100:
lda work_lo
sec
sbc #100
bcc done_100
sta work_lo
inx
jmp div_100
done_100:
txa
ora #$30
sta SCREEN + 10
ldx #0
div_10:
lda work_lo
sec
sbc #10
bcc done_10
sta work_lo
inx
jmp div_10
done_10:
txa
ora #$30
sta SCREEN + 11
lda work_lo
ora #$30
sta SCREEN + 12
lda #7
sta COLRAM + 8
sta COLRAM + 9
sta COLRAM + 10
sta COLRAM + 11
sta COLRAM + 12
rts
; ----------------------------------------------------------------------------
; Display Misses
; ----------------------------------------------------------------------------
display_misses:
lda miss_count
ldx #0
miss_div_10:
cmp #10
bcc miss_done_10
sec
sbc #10
inx
jmp miss_div_10
miss_done_10:
pha
txa
ora #$30
sta SCREEN + 21
pla
ora #$30
sta SCREEN + 22
lda #2
sta COLRAM + 21
sta COLRAM + 22
rts
work_lo: !byte 0
work_hi: !byte 0
; ----------------------------------------------------------------------------
; Play Voices
; ----------------------------------------------------------------------------
play_voice1:
lda #VOICE1_WAVE
ora #$01
sta SID_V1_CTRL
rts
play_voice2:
lda #VOICE2_WAVE
ora #$01
sta SID_V2_CTRL
rts
play_voice3:
lda #VOICE3_WAVE
ora #$01
sta SID_V3_CTRL
rts
; ----------------------------------------------------------------------------
; Flash Tracks on Hit
; ----------------------------------------------------------------------------
flash_track1_hit:
ldx #0
lda #HIT_COL
flash_t1h_loop:
sta COLRAM + (TRACK1_ROW * 40),x
inx
cpx #38
bne flash_t1h_loop
lda #1
sta COLRAM + (TRACK1_ROW * 40)
rts
flash_track2_hit:
ldx #0
lda #HIT_COL
flash_t2h_loop:
sta COLRAM + (TRACK2_ROW * 40),x
inx
cpx #38
bne flash_t2h_loop
lda #1
sta COLRAM + (TRACK2_ROW * 40)
rts
flash_track3_hit:
ldx #0
lda #HIT_COL
flash_t3h_loop:
sta COLRAM + (TRACK3_ROW * 40),x
inx
cpx #38
bne flash_t3h_loop
lda #1
sta COLRAM + (TRACK3_ROW * 40)
rts
; ----------------------------------------------------------------------------
; Song Data
; ----------------------------------------------------------------------------
song_data:
!byte 0, 1
!byte 2, 2
!byte 4, 3
!byte 6, 1
!byte 8, 2
!byte 10, 3
!byte 12, 1
!byte 14, 2
!byte 16, 3
!byte 18, 1
!byte 20, 2
!byte 22, 3
!byte 24, 1
!byte 25, 2
!byte 26, 3
!byte 28, 1
!byte 29, 2
!byte 30, 3
!byte $FF
; ----------------------------------------------------------------------------
; Note Arrays
; ----------------------------------------------------------------------------
note_track:
!fill MAX_NOTES, 0
note_col:
!fill MAX_NOTES, 0
; ----------------------------------------------------------------------------
; Game Variables
; ----------------------------------------------------------------------------
score_lo: !byte 0
score_hi: !byte 0
miss_count: !byte 0
health: !byte 0
Try This: Different Balance
Adjust the difficulty by changing health values:
HEALTH_PERFECT = 2 ; Less reward
HEALTH_GOOD = 1
HEALTH_MISS = 12 ; Harsher punishmentThis makes the game harder - misses hurt more, hits help less. Find a balance that feels challenging but fair.
Try This: Visual Health Feedback
Change the bar colour based on health level:
display_health:
lda health
cmp #16
bcc health_critical
lda #5 ; Green
jmp set_health_col
health_critical:
lda #2 ; Red when low
set_health_col:
sta health_colour
; ... use health_colour instead of HEALTH_COLRed when critical makes danger obvious.
What You’ve Learnt
- Clamped values - Preventing overflow and underflow with comparisons
- Bit shifting for division - LSR divides by 2, three shifts divide by 8
- Game state flags - A simple variable to track game over condition
- Visual bars - Custom characters for progress display
What’s Next
In Unit 9, we’ll design the song data format. Real songs with multiple patterns, variable timing, and musical structure. The placeholder test pattern becomes actual music.
What Changed
Unit 7 → Unit 8
+234-27
| 1 | 1 | ; ============================================================================ | |
| 2 | - | ; SID SYMPHONY - Unit 7: Miss Handling | |
| 2 | + | ; SID SYMPHONY - Unit 8: Health System | |
| 3 | 3 | ; ============================================================================ | |
| 4 | - | ; Notes that scroll past unhit trigger negative feedback. A harsh noise burst | |
| 5 | - | ; and red flash punish mistakes. Miss count tracks failures. | |
| 4 | + | ; A health meter that grows on hits and shrinks on misses. The game can be | |
| 5 | + | ; lost. Stakes make success meaningful. | |
| 6 | 6 | ; | |
| 7 | 7 | ; Controls: Z = Track 1 (high), X = Track 2 (mid), C = Track 3 (low) | |
| 8 | 8 | ; ============================================================================ | |
| ... | |||
| 49 | 49 | PERFECT_COL = 1 ; White - perfect hit border flash | |
| 50 | 50 | GOOD_COL = 7 ; Yellow - good hit border flash | |
| 51 | 51 | MISS_COL = 2 ; Red - miss border flash | |
| 52 | + | | |
| 53 | + | HEALTH_COL = 5 ; Green for health bar | |
| 52 | 54 | | |
| 53 | 55 | ; ============================================================================ | |
| 54 | 56 | ; SCORING SETTINGS | |
| ... | |||
| 56 | 58 | | |
| 57 | 59 | PERFECT_SCORE = 100 | |
| 58 | 60 | GOOD_SCORE = 50 | |
| 61 | + | | |
| 62 | + | ; ============================================================================ | |
| 63 | + | ; HEALTH SETTINGS | |
| 64 | + | ; ============================================================================ | |
| 65 | + | | |
| 66 | + | HEALTH_MAX = 64 ; Maximum health | |
| 67 | + | HEALTH_START = 32 ; Starting health (half) | |
| 68 | + | HEALTH_PERFECT = 4 ; Health gained on perfect hit | |
| 69 | + | HEALTH_GOOD = 2 ; Health gained on good hit | |
| 70 | + | HEALTH_MISS = 8 ; Health lost on miss | |
| 59 | 71 | | |
| 60 | 72 | ; ============================================================================ | |
| 61 | 73 | ; HIT DETECTION SETTINGS | |
| ... | |||
| 110 | 122 | TRACK1_ROW = 8 | |
| 111 | 123 | TRACK2_ROW = 12 | |
| 112 | 124 | TRACK3_ROW = 16 | |
| 125 | + | | |
| 126 | + | ; Health bar position | |
| 127 | + | HEALTH_ROW = 23 | |
| 113 | 128 | | |
| 114 | 129 | ; Hit zone | |
| 115 | 130 | HIT_ZONE_COLUMN = 3 | |
| ... | |||
| 119 | 134 | CHAR_TRACK = 129 | |
| 120 | 135 | CHAR_HITZONE = 130 | |
| 121 | 136 | CHAR_SPACE = 32 | |
| 137 | + | CHAR_BAR_FULL = 131 | |
| 138 | + | CHAR_BAR_EMPTY = 132 | |
| 122 | 139 | | |
| 123 | 140 | ; Note settings | |
| 124 | 141 | MAX_NOTES = 8 | |
| ... | |||
| 140 | 157 | key_pressed = $07 | |
| 141 | 158 | hit_quality = $08 | |
| 142 | 159 | border_flash = $09 | |
| 143 | - | miss_track = $0A ; Track of missed note (for flash) | |
| 160 | + | miss_track = $0A | |
| 161 | + | game_over = $0B ; Non-zero when game ended | |
| 144 | 162 | | |
| 145 | 163 | ; ---------------------------------------------------------------------------- | |
| 146 | 164 | ; BASIC Stub | |
| ... | |||
| 167 | 185 | jsr init_sid | |
| 168 | 186 | jsr init_notes | |
| 169 | 187 | jsr init_score | |
| 188 | + | jsr init_health | |
| 170 | 189 | | |
| 171 | 190 | lda #<song_data | |
| 172 | 191 | sta song_pos | |
| ... | |||
| 177 | 196 | sta frame_count | |
| 178 | 197 | sta beat_count | |
| 179 | 198 | sta border_flash | |
| 199 | + | sta game_over | |
| 180 | 200 | | |
| 181 | 201 | main_loop: | |
| 182 | 202 | lda #$FF | |
| 183 | 203 | wait_raster: | |
| 184 | 204 | cmp $D012 | |
| 185 | 205 | bne wait_raster | |
| 206 | + | | |
| 207 | + | ; Check if game is over | |
| 208 | + | lda game_over | |
| 209 | + | bne main_loop ; Freeze if game over | |
| 186 | 210 | | |
| 187 | 211 | inc frame_count | |
| 188 | 212 | lda frame_count | |
| ... | |||
| 252 | 276 | ; ---------------------------------------------------------------------------- | |
| 253 | 277 | | |
| 254 | 278 | define_custom_chars: | |
| 279 | + | ; Note character - diamond shape | |
| 255 | 280 | lda #%00000110 | |
| 256 | 281 | sta CHARSET + (CHAR_NOTE * 8) + 0 | |
| 257 | 282 | lda #%00011110 | |
| ... | |||
| 269 | 294 | lda #%00000110 | |
| 270 | 295 | sta CHARSET + (CHAR_NOTE * 8) + 7 | |
| 271 | 296 | | |
| 297 | + | ; Track character - horizontal line | |
| 272 | 298 | lda #%00000000 | |
| 273 | 299 | sta CHARSET + (CHAR_TRACK * 8) + 0 | |
| 274 | 300 | lda #%00000000 | |
| ... | |||
| 286 | 312 | lda #%00000000 | |
| 287 | 313 | sta CHARSET + (CHAR_TRACK * 8) + 7 | |
| 288 | 314 | | |
| 315 | + | ; Hit zone character - vertical bars | |
| 289 | 316 | lda #%01100110 | |
| 290 | 317 | sta CHARSET + (CHAR_HITZONE * 8) + 0 | |
| 291 | 318 | sta CHARSET + (CHAR_HITZONE * 8) + 1 | |
| ... | |||
| 295 | 322 | sta CHARSET + (CHAR_HITZONE * 8) + 5 | |
| 296 | 323 | sta CHARSET + (CHAR_HITZONE * 8) + 6 | |
| 297 | 324 | sta CHARSET + (CHAR_HITZONE * 8) + 7 | |
| 325 | + | | |
| 326 | + | ; Health bar full - solid block | |
| 327 | + | lda #%11111111 | |
| 328 | + | sta CHARSET + (CHAR_BAR_FULL * 8) + 0 | |
| 329 | + | sta CHARSET + (CHAR_BAR_FULL * 8) + 1 | |
| 330 | + | sta CHARSET + (CHAR_BAR_FULL * 8) + 2 | |
| 331 | + | sta CHARSET + (CHAR_BAR_FULL * 8) + 3 | |
| 332 | + | sta CHARSET + (CHAR_BAR_FULL * 8) + 4 | |
| 333 | + | sta CHARSET + (CHAR_BAR_FULL * 8) + 5 | |
| 334 | + | sta CHARSET + (CHAR_BAR_FULL * 8) + 6 | |
| 335 | + | sta CHARSET + (CHAR_BAR_FULL * 8) + 7 | |
| 336 | + | | |
| 337 | + | ; Health bar empty - outline | |
| 338 | + | lda #%11111111 | |
| 339 | + | sta CHARSET + (CHAR_BAR_EMPTY * 8) + 0 | |
| 340 | + | lda #%10000001 | |
| 341 | + | sta CHARSET + (CHAR_BAR_EMPTY * 8) + 1 | |
| 342 | + | sta CHARSET + (CHAR_BAR_EMPTY * 8) + 2 | |
| 343 | + | sta CHARSET + (CHAR_BAR_EMPTY * 8) + 3 | |
| 344 | + | sta CHARSET + (CHAR_BAR_EMPTY * 8) + 4 | |
| 345 | + | sta CHARSET + (CHAR_BAR_EMPTY * 8) + 5 | |
| 346 | + | sta CHARSET + (CHAR_BAR_EMPTY * 8) + 6 | |
| 347 | + | lda #%11111111 | |
| 348 | + | sta CHARSET + (CHAR_BAR_EMPTY * 8) + 7 | |
| 349 | + | | |
| 350 | + | rts | |
| 351 | + | | |
| 352 | + | ; ---------------------------------------------------------------------------- | |
| 353 | + | ; Initialize Health | |
| 354 | + | ; ---------------------------------------------------------------------------- | |
| 298 | 355 | | |
| 356 | + | init_health: | |
| 357 | + | lda #HEALTH_START | |
| 358 | + | sta health | |
| 359 | + | jsr display_health | |
| 299 | 360 | rts | |
| 300 | 361 | | |
| 301 | 362 | ; ---------------------------------------------------------------------------- | |
| ... | |||
| 396 | 457 | rts | |
| 397 | 458 | | |
| 398 | 459 | ; ---------------------------------------------------------------------------- | |
| 399 | - | ; Update Notes - Now detects misses | |
| 460 | + | ; Update Notes | |
| 400 | 461 | ; ---------------------------------------------------------------------------- | |
| 401 | 462 | | |
| 402 | 463 | update_notes: | |
| ... | |||
| 411 | 472 | dec note_col,x | |
| 412 | 473 | lda note_col,x | |
| 413 | 474 | cmp #1 | |
| 414 | - | bcc update_miss ; Note passed hit zone - MISS! | |
| 475 | + | bcc update_miss | |
| 415 | 476 | | |
| 416 | 477 | jsr draw_note | |
| 417 | 478 | jmp update_next | |
| 418 | 479 | | |
| 419 | 480 | update_miss: | |
| 420 | - | ; Note fell through - record the miss | |
| 421 | 481 | lda note_track,x | |
| 422 | - | sta miss_track ; Save which track for flash | |
| 482 | + | sta miss_track | |
| 423 | 483 | lda #0 | |
| 424 | - | sta note_track,x ; Deactivate note | |
| 425 | - | jsr handle_miss ; Process the miss | |
| 484 | + | sta note_track,x | |
| 485 | + | jsr handle_miss | |
| 426 | 486 | | |
| 427 | 487 | update_next: | |
| 428 | 488 | inx | |
| ... | |||
| 431 | 491 | rts | |
| 432 | 492 | | |
| 433 | 493 | ; ---------------------------------------------------------------------------- | |
| 434 | - | ; Handle Miss - Negative feedback for missed notes | |
| 494 | + | ; Handle Miss | |
| 435 | 495 | ; ---------------------------------------------------------------------------- | |
| 436 | 496 | | |
| 437 | 497 | handle_miss: | |
| 438 | - | ; Increment miss counter | |
| 439 | 498 | inc miss_count | |
| 440 | 499 | | |
| 441 | - | ; Play miss sound (harsh noise burst) | |
| 442 | 500 | jsr play_miss_sound | |
| 443 | 501 | | |
| 444 | - | ; Red border flash | |
| 445 | 502 | lda #MISS_COL | |
| 446 | 503 | sta BORDER | |
| 447 | - | lda #8 ; Flash for 8 frames | |
| 504 | + | lda #8 | |
| 448 | 505 | sta border_flash | |
| 449 | 506 | | |
| 450 | - | ; Update miss display | |
| 451 | 507 | jsr display_misses | |
| 508 | + | | |
| 509 | + | ; Decrease health | |
| 510 | + | jsr decrease_health | |
| 452 | 511 | | |
| 453 | 512 | rts | |
| 454 | 513 | | |
| 455 | 514 | ; ---------------------------------------------------------------------------- | |
| 456 | - | ; Play Miss Sound - Harsh noise burst | |
| 515 | + | ; Decrease Health - Subtract HEALTH_MISS, clamp at 0 | |
| 516 | + | ; ---------------------------------------------------------------------------- | |
| 517 | + | | |
| 518 | + | decrease_health: | |
| 519 | + | lda health | |
| 520 | + | sec | |
| 521 | + | sbc #HEALTH_MISS | |
| 522 | + | bcc health_zero ; Underflow - set to 0 | |
| 523 | + | sta health | |
| 524 | + | jsr display_health | |
| 525 | + | jsr check_game_over | |
| 526 | + | rts | |
| 527 | + | | |
| 528 | + | health_zero: | |
| 529 | + | lda #0 | |
| 530 | + | sta health | |
| 531 | + | jsr display_health | |
| 532 | + | jsr check_game_over | |
| 533 | + | rts | |
| 534 | + | | |
| 535 | + | ; ---------------------------------------------------------------------------- | |
| 536 | + | ; Increase Health - Add amount, clamp at HEALTH_MAX | |
| 537 | + | ; Input: A = amount to add | |
| 538 | + | ; ---------------------------------------------------------------------------- | |
| 539 | + | | |
| 540 | + | increase_health: | |
| 541 | + | clc | |
| 542 | + | adc health | |
| 543 | + | cmp #HEALTH_MAX | |
| 544 | + | bcc health_ok | |
| 545 | + | lda #HEALTH_MAX ; Clamp to max | |
| 546 | + | health_ok: | |
| 547 | + | sta health | |
| 548 | + | jsr display_health | |
| 549 | + | rts | |
| 550 | + | | |
| 551 | + | ; ---------------------------------------------------------------------------- | |
| 552 | + | ; Check Game Over | |
| 553 | + | ; ---------------------------------------------------------------------------- | |
| 554 | + | | |
| 555 | + | check_game_over: | |
| 556 | + | lda health | |
| 557 | + | bne not_game_over | |
| 558 | + | | |
| 559 | + | ; Game over! | |
| 560 | + | lda #1 | |
| 561 | + | sta game_over | |
| 562 | + | | |
| 563 | + | ; Display game over message | |
| 564 | + | jsr show_game_over | |
| 565 | + | | |
| 566 | + | not_game_over: | |
| 567 | + | rts | |
| 568 | + | | |
| 569 | + | ; ---------------------------------------------------------------------------- | |
| 570 | + | ; Show Game Over | |
| 571 | + | ; ---------------------------------------------------------------------------- | |
| 572 | + | | |
| 573 | + | show_game_over: | |
| 574 | + | ; Display "GAME OVER" in centre of screen | |
| 575 | + | ldx #0 | |
| 576 | + | game_over_loop: | |
| 577 | + | lda game_over_text,x | |
| 578 | + | beq game_over_done | |
| 579 | + | sta SCREEN + (12 * 40) + 15,x | |
| 580 | + | lda #2 ; Red | |
| 581 | + | sta COLRAM + (12 * 40) + 15,x | |
| 582 | + | inx | |
| 583 | + | jmp game_over_loop | |
| 584 | + | game_over_done: | |
| 585 | + | | |
| 586 | + | ; Flash border red | |
| 587 | + | lda #2 | |
| 588 | + | sta BORDER | |
| 589 | + | | |
| 590 | + | rts | |
| 591 | + | | |
| 592 | + | game_over_text: | |
| 593 | + | !scr "game over" | |
| 594 | + | !byte 0 | |
| 595 | + | | |
| 596 | + | ; ---------------------------------------------------------------------------- | |
| 597 | + | ; Display Health - 8 character bar | |
| 598 | + | ; ---------------------------------------------------------------------------- | |
| 599 | + | | |
| 600 | + | display_health: | |
| 601 | + | ; Health ranges 0-64, displayed as 8 characters | |
| 602 | + | ; Each character represents 8 health points | |
| 603 | + | | |
| 604 | + | lda health | |
| 605 | + | lsr ; Divide by 8 | |
| 606 | + | lsr | |
| 607 | + | lsr | |
| 608 | + | sta temp_health ; Full bars to draw | |
| 609 | + | | |
| 610 | + | ; Draw full bars | |
| 611 | + | ldx #0 | |
| 612 | + | lda temp_health | |
| 613 | + | beq draw_empty_bars | |
| 614 | + | | |
| 615 | + | draw_full_bars: | |
| 616 | + | lda #CHAR_BAR_FULL | |
| 617 | + | sta SCREEN + (HEALTH_ROW * 40) + 16,x | |
| 618 | + | lda #HEALTH_COL | |
| 619 | + | sta COLRAM + (HEALTH_ROW * 40) + 16,x | |
| 620 | + | inx | |
| 621 | + | cpx temp_health | |
| 622 | + | bne draw_full_bars | |
| 623 | + | | |
| 624 | + | ; Draw empty bars for remainder | |
| 625 | + | draw_empty_bars: | |
| 626 | + | cpx #8 | |
| 627 | + | beq health_done | |
| 628 | + | lda #CHAR_BAR_EMPTY | |
| 629 | + | sta SCREEN + (HEALTH_ROW * 40) + 16,x | |
| 630 | + | lda #11 ; Dark grey | |
| 631 | + | sta COLRAM + (HEALTH_ROW * 40) + 16,x | |
| 632 | + | inx | |
| 633 | + | jmp draw_empty_bars | |
| 634 | + | | |
| 635 | + | health_done: | |
| 636 | + | rts | |
| 637 | + | | |
| 638 | + | temp_health: !byte 0 | |
| 639 | + | | |
| 640 | + | ; ---------------------------------------------------------------------------- | |
| 641 | + | ; Play Miss Sound | |
| 457 | 642 | ; ---------------------------------------------------------------------------- | |
| 458 | 643 | | |
| 459 | 644 | play_miss_sound: | |
| 460 | - | ; Use voice 3 for miss sound (temporary override) | |
| 461 | 645 | lda #0 | |
| 462 | 646 | sta SID_V3_FREQ_LO | |
| 463 | 647 | lda #MISS_FREQ | |
| ... | |||
| 467 | 651 | lda #MISS_SR | |
| 468 | 652 | sta SID_V3_SR | |
| 469 | 653 | lda #MISS_WAVE | |
| 470 | - | ora #$01 ; Gate on | |
| 654 | + | ora #$01 | |
| 471 | 655 | sta SID_V3_CTRL | |
| 472 | 656 | rts | |
| 473 | 657 | | |
| ... | |||
| 771 | 955 | lda miss_label,x | |
| 772 | 956 | beq draw_miss_label_done | |
| 773 | 957 | sta SCREEN + 15,x | |
| 774 | - | lda #2 ; Red | |
| 958 | + | lda #2 | |
| 775 | 959 | sta COLRAM + 15,x | |
| 776 | 960 | inx | |
| 777 | 961 | bne draw_miss_label | |
| ... | |||
| 788 | 972 | inx | |
| 789 | 973 | bne draw_title | |
| 790 | 974 | draw_title_done: | |
| 975 | + | | |
| 976 | + | ; Draw "HEALTH:" label | |
| 977 | + | ldx #0 | |
| 978 | + | draw_health_label: | |
| 979 | + | lda health_label,x | |
| 980 | + | beq draw_health_label_done | |
| 981 | + | sta SCREEN + (HEALTH_ROW * 40) + 8,x | |
| 982 | + | lda #5 ; Green | |
| 983 | + | sta COLRAM + (HEALTH_ROW * 40) + 8,x | |
| 984 | + | inx | |
| 985 | + | bne draw_health_label | |
| 986 | + | draw_health_label_done: | |
| 791 | 987 | | |
| 792 | 988 | ; Track labels | |
| 793 | 989 | lda #$1A ; Z | |
| ... | |||
| 817 | 1013 | | |
| 818 | 1014 | title_text: | |
| 819 | 1015 | !scr "sid symphony" | |
| 1016 | + | !byte 0 | |
| 1017 | + | | |
| 1018 | + | health_label: | |
| 1019 | + | !scr "health:" | |
| 820 | 1020 | !byte 0 | |
| 821 | 1021 | | |
| 822 | 1022 | ; ---------------------------------------------------------------------------- | |
| ... | |||
| 1067 | 1267 | sta BORDER | |
| 1068 | 1268 | lda #4 | |
| 1069 | 1269 | sta border_flash | |
| 1270 | + | | |
| 1271 | + | ; Increase health for good hit | |
| 1272 | + | lda #HEALTH_GOOD | |
| 1273 | + | jsr increase_health | |
| 1070 | 1274 | | |
| 1071 | 1275 | jmp award_done | |
| 1072 | 1276 | | |
| ... | |||
| 1083 | 1287 | sta BORDER | |
| 1084 | 1288 | lda #6 | |
| 1085 | 1289 | sta border_flash | |
| 1290 | + | | |
| 1291 | + | ; Increase health for perfect hit | |
| 1292 | + | lda #HEALTH_PERFECT | |
| 1293 | + | jsr increase_health | |
| 1086 | 1294 | | |
| 1087 | 1295 | award_done: | |
| 1088 | 1296 | jsr display_score | |
| ... | |||
| 1176 | 1384 | rts | |
| 1177 | 1385 | | |
| 1178 | 1386 | ; ---------------------------------------------------------------------------- | |
| 1179 | - | ; Display Misses - Simple 2-digit display | |
| 1387 | + | ; Display Misses | |
| 1180 | 1388 | ; ---------------------------------------------------------------------------- | |
| 1181 | 1389 | | |
| 1182 | 1390 | display_misses: | |
| 1183 | 1391 | lda miss_count | |
| 1184 | 1392 | | |
| 1185 | - | ; Tens digit | |
| 1186 | 1393 | ldx #0 | |
| 1187 | 1394 | miss_div_10: | |
| 1188 | 1395 | cmp #10 | |
| ... | |||
| 1192 | 1399 | inx | |
| 1193 | 1400 | jmp miss_div_10 | |
| 1194 | 1401 | miss_done_10: | |
| 1195 | - | ; X = tens, A = ones | |
| 1196 | - | pha ; Save ones | |
| 1402 | + | pha | |
| 1197 | 1403 | txa | |
| 1198 | 1404 | ora #$30 | |
| 1199 | - | sta SCREEN + 21 ; Tens digit | |
| 1405 | + | sta SCREEN + 21 | |
| 1200 | 1406 | pla | |
| 1201 | 1407 | ora #$30 | |
| 1202 | - | sta SCREEN + 22 ; Ones digit | |
| 1408 | + | sta SCREEN + 22 | |
| 1203 | 1409 | | |
| 1204 | - | lda #2 ; Red | |
| 1410 | + | lda #2 | |
| 1205 | 1411 | sta COLRAM + 21 | |
| 1206 | 1412 | sta COLRAM + 22 | |
| 1207 | 1413 | | |
| ... | |||
| 1318 | 1524 | score_lo: !byte 0 | |
| 1319 | 1525 | score_hi: !byte 0 | |
| 1320 | 1526 | miss_count: !byte 0 | |
| 1527 | + | health: !byte 0 | |
| 1321 | 1528 | |