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Game 1 Unit 14 of 64 1 hr learning time

Game Over Screen

Handle failure. Show game over. Distinct from successful completion.

22% of SID Symphony

Failure needs its own moment. This unit gives the game over state proper treatment.

Previously, running out of health showed “GAME OVER” overlaid on the gameplay screen. Now the game clears to a dedicated display: “GAME OVER” in red, “HEALTH DEPLETED” explaining why, the score you achieved, and how many notes you hit before failing. The red border reinforces failure, distinct from the green border of success.

Run It

Assemble and run:

acme -f cbm -o symphony.prg symphony.asm

Unit 14 Screenshot

Press fire to start, then deliberately miss notes until your health depletes. You’ll see the new game over screen.

Game over screen — shown when health reaches zero

Success vs Failure

The game now has two distinct endings:

AspectResults (Success)Game Over (Failure)
TriggerSong completesHealth reaches 0
Title”SONG COMPLETE!""GAME OVER”
ColourGreen borderRed border
StatsFull breakdownScore + notes hit
FeelingAchievementTry again

Players immediately know whether they succeeded or failed from the visual language.

The Game Over Display

The game over screen provides closure on failure:

; ----------------------------------------------------------------------------
; Show Game Over - Dedicated full-screen display for failure
; ----------------------------------------------------------------------------

show_game_over:
            ; Clear screen for game over display
            ldx #0
            lda #CHAR_SPACE
clear_gameover:
            sta SCREEN,x
            sta SCREEN+$100,x
            sta SCREEN+$200,x
            sta SCREEN+$2E8,x
            inx
            bne clear_gameover

            ; Draw "GAME OVER" in red
            ldx #0
game_over_loop:
            lda game_over_text,x
            beq game_over_text_done
            sta SCREEN + (6 * 40) + 15,x
            lda #2                  ; Red for failure
            sta COLRAM + (6 * 40) + 15,x
            inx
            jmp game_over_loop
game_over_text_done:

            ; Draw "HEALTH DEPLETED" - explains why
            ldx #0
draw_depleted:
            lda depleted_text,x
            beq draw_depleted_done
            sta SCREEN + (8 * 40) + 12,x
            lda #10                 ; Light red
            sta COLRAM + (8 * 40) + 12,x
            inx
            jmp draw_depleted
draw_depleted_done:

            ; Show score achieved
            jsr display_gameover_score

            ; Show notes hit
            jsr display_notes_hit

            ; "PRESS FIRE FOR TITLE"
            ldx #0
game_over_press:
            lda press_fire_gameover,x
            beq game_over_done
            sta SCREEN + (18 * 40) + 10,x
            lda #7                  ; Yellow for action
            sta COLRAM + (18 * 40) + 10,x
            inx
            jmp game_over_press

game_over_done:
            lda #2                  ; Red border for failure
            sta BORDER
            rts

game_over_text:
            !scr "game over"
            !byte 0

depleted_text:
            !scr "health depleted"
            !byte 0

press_fire_gameover:
            !scr "press fire for title"
            !byte 0

Three key elements:

  1. “GAME OVER” in red - immediately communicates failure
  2. “HEALTH DEPLETED” - explains why the game ended
  3. Score and notes hit - shows progress before failure

Colour Communicates State

The red colour scheme signals failure:

            lda #2                  ; Red for failure
            sta COLRAM + (6 * 40) + 15,x   ; Title colour

            ; ...later...

            lda #2                  ; Red border
            sta BORDER

Compare to the results screen’s green border:

            lda #5                  ; Green border for success
            sta BORDER

Players don’t need to read text to understand the outcome.

Showing Partial Progress

Unlike the success screen, the game over shows simplified stats:

            ; Show score achieved
            jsr display_gameover_score

            ; Show notes hit (perfects + goods)
            lda perfect_count
            clc
            adc good_count
            jsr display_go_stat

We don’t show accuracy or max combo - that level of detail is for success. For failure, we show what was achieved before the end.

The Complete Code

; ============================================================================
; SID SYMPHONY - Unit 14: Game Over Screen
; ============================================================================
; Improved game over screen when health depletes. Clear display showing
; failure distinctly from success. Score shown, red colour scheme.
;
; Controls: Z = Track 1 (high), X = Track 2 (mid), C = Track 3 (low)
;           Fire = Start game from title screen
; ============================================================================

; ============================================================================
; CUSTOMISATION SECTION
; ============================================================================

; SID Voice Settings
VOICE1_WAVE = $21
VOICE2_WAVE = $41
VOICE3_WAVE = $11

VOICE1_FREQ = $1C
VOICE2_FREQ = $0E
VOICE3_FREQ = $07

VOICE_AD    = $09
VOICE_SR    = $00
PULSE_WIDTH = $08

; Miss sound settings
MISS_FREQ   = $08
MISS_WAVE   = $81
MISS_AD     = $00
MISS_SR     = $90

; Visual Settings
BORDER_COL  = 0
BG_COL      = 0

TRACK1_NOTE_COL = 10
TRACK2_NOTE_COL = 13
TRACK3_NOTE_COL = 14

TRACK_LINE_COL = 11
HIT_ZONE_COL = 7

HIT_COL     = 1
PERFECT_COL = 1
GOOD_COL    = 7
MISS_COL    = 2

HEALTH_COL  = 5
PROGRESS_COL = 3
COMBO_COL   = 13

; Title screen colours
TITLE_COL   = 1                 ; White for title
SUBTITLE_COL = 11               ; Grey for subtitle

; ============================================================================
; SCORING SETTINGS
; ============================================================================

PERFECT_SCORE = 100
GOOD_SCORE    = 50

; ============================================================================
; COMBO SETTINGS
; ============================================================================

COMBO_TIER_2  = 10
COMBO_TIER_3  = 25
COMBO_TIER_4  = 50

; ============================================================================
; HEALTH SETTINGS
; ============================================================================

HEALTH_MAX    = 64
HEALTH_START  = 32
HEALTH_PERFECT = 4
HEALTH_GOOD   = 2
HEALTH_MISS   = 8

; ============================================================================
; HIT DETECTION SETTINGS
; ============================================================================

HIT_ZONE_MIN = 2
HIT_ZONE_MAX = 5
HIT_ZONE_CENTRE = 3

; ============================================================================
; SONG SETTINGS
; ============================================================================

SONG_LENGTH   = 64
PROGRESS_WIDTH = 16

; ============================================================================
; GAME STATES
; ============================================================================

STATE_TITLE   = 0               ; NEW: Title screen
STATE_PLAYING = 1
STATE_RESULTS = 2
STATE_GAMEOVER = 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 and joystick
CIA1_PRA    = $DC00
CIA1_PRB    = $DC01

; Track positions
TRACK1_ROW  = 8
TRACK2_ROW  = 12
TRACK3_ROW  = 16

; HUD positions
HEALTH_ROW  = 23
PROGRESS_ROW = 24

; Combo display position
COMBO_ROW   = 2

; 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
END_DELAY_FRAMES = 75

; 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_state  = $0B
hit_note_freq = $0C
song_beat   = $0D
song_ended  = $0E
end_delay   = $0F

; ----------------------------------------------------------------------------
; 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_sid
            jsr show_title

            ; Start in TITLE state
            lda #STATE_TITLE
            sta game_state

main_loop:
            lda #$FF
wait_raster:
            cmp $D012
            bne wait_raster

            lda game_state
            cmp #STATE_TITLE
            beq do_title
            cmp #STATE_PLAYING
            beq do_playing
            cmp #STATE_RESULTS
            beq do_results
            jmp do_gameover

do_title:
            jsr update_title
            jmp main_loop

do_playing:
            jsr update_playing
            jmp main_loop

do_results:
            jsr update_results
            jmp main_loop

do_gameover:
            jsr update_gameover
            jmp main_loop

; ----------------------------------------------------------------------------
; Show Title Screen
; ----------------------------------------------------------------------------

show_title:
            ; Clear screen
            lda #BORDER_COL
            sta BORDER
            lda #BG_COL
            sta BGCOL

            ldx #0
            lda #CHAR_SPACE
clear_title:
            sta SCREEN,x
            sta SCREEN+$100,x
            sta SCREEN+$200,x
            sta SCREEN+$2E8,x
            inx
            bne clear_title

            ; Draw big title "SID SYMPHONY"
            ldx #0
draw_title_text:
            lda title_big,x
            beq draw_title_done
            sta SCREEN + (8 * 40) + 14,x
            lda #TITLE_COL
            sta COLRAM + (8 * 40) + 14,x
            inx
            jmp draw_title_text
draw_title_done:

            ; Draw subtitle "A RHYTHM GAME"
            ldx #0
draw_subtitle:
            lda subtitle_text,x
            beq draw_subtitle_done
            sta SCREEN + (10 * 40) + 13,x
            lda #SUBTITLE_COL
            sta COLRAM + (10 * 40) + 13,x
            inx
            jmp draw_subtitle
draw_subtitle_done:

            ; Draw controls
            ldx #0
draw_controls:
            lda controls_text,x
            beq draw_controls_done
            sta SCREEN + (14 * 40) + 11,x
            lda #11
            sta COLRAM + (14 * 40) + 11,x
            inx
            jmp draw_controls
draw_controls_done:

            ; Draw track info
            ldx #0
draw_track_info:
            lda track_info,x
            beq draw_track_done
            sta SCREEN + (16 * 40) + 9,x
            lda #11
            sta COLRAM + (16 * 40) + 9,x
            inx
            jmp draw_track_info
draw_track_done:

            ; Draw "PRESS FIRE TO START"
            ldx #0
draw_press_fire:
            lda press_fire_text,x
            beq draw_press_done
            sta SCREEN + (20 * 40) + 10,x
            lda #7              ; Yellow
            sta COLRAM + (20 * 40) + 10,x
            inx
            jmp draw_press_fire
draw_press_done:

            rts

title_big:
            !scr "sid symphony"
            !byte 0

subtitle_text:
            !scr "a rhythm game"
            !byte 0

controls_text:
            !scr "controls: z / x / c"
            !byte 0

track_info:
            !scr "hit notes as they reach"
            !byte 0

press_fire_text:
            !scr "press fire to start"
            !byte 0

; ----------------------------------------------------------------------------
; Update Title State
; ----------------------------------------------------------------------------

update_title:
            ; Check for fire button (joystick port 2)
            lda CIA1_PRA
            and #$10            ; Bit 4 = fire
            beq fire_pressed

            ; Also check space bar as alternative
            lda #$7F
            sta CIA1_PRA
            lda CIA1_PRB
            and #$10            ; Space
            beq fire_pressed

            ; No input - stay on title
            lda #$FF
            sta CIA1_PRA
            rts

fire_pressed:
            lda #$FF
            sta CIA1_PRA

            ; Start the game!
            jsr init_game
            lda #STATE_PLAYING
            sta game_state
            rts

; ----------------------------------------------------------------------------
; Initialize Game (called when starting from title)
; ----------------------------------------------------------------------------

init_game:
            jsr init_screen
            jsr init_notes
            jsr init_score
            jsr init_health
            jsr init_combo
            jsr init_song

            rts

; ----------------------------------------------------------------------------
; Initialize Combo
; ----------------------------------------------------------------------------

init_combo:
            lda #0
            sta combo
            sta max_combo
            jsr display_combo
            rts

; ----------------------------------------------------------------------------
; Update Playing State
; ----------------------------------------------------------------------------

update_playing:
            inc frame_count
            lda frame_count
            cmp #FRAMES_PER_BEAT
            bcc no_new_beat

            lda #0
            sta frame_count
            jsr advance_song
            jsr check_spawn_note

no_new_beat:
            jsr update_notes
            jsr reset_track_colours
            jsr update_border_flash
            jsr check_keys
            jsr check_song_end

            rts

; ----------------------------------------------------------------------------
; Update Results State
; ----------------------------------------------------------------------------

update_results:
            ; Check for fire to return to title
            lda CIA1_PRA
            and #$10
            beq results_fire

            ; Also check space bar
            lda #$7F
            sta CIA1_PRA
            lda CIA1_PRB
            and #$10
            beq results_fire

            lda #$FF
            sta CIA1_PRA
            rts

results_fire:
            lda #$FF
            sta CIA1_PRA

            ; Return to title screen
            jsr show_title
            lda #STATE_TITLE
            sta game_state
            rts

; ----------------------------------------------------------------------------
; Update Game Over State
; ----------------------------------------------------------------------------

update_gameover:
            ; Check for fire to return to title
            lda CIA1_PRA
            and #$10
            beq gameover_fire

            lda #$7F
            sta CIA1_PRA
            lda CIA1_PRB
            and #$10
            beq gameover_fire

            lda #$FF
            sta CIA1_PRA
            rts

gameover_fire:
            lda #$FF
            sta CIA1_PRA

            ; Return to title screen
            jsr show_title
            lda #STATE_TITLE
            sta game_state
            rts

; ----------------------------------------------------------------------------
; Check Song End
; ----------------------------------------------------------------------------

check_song_end:
            lda song_ended
            beq song_not_ended

            ldx #0
check_notes_clear:
            lda note_track,x
            bne notes_still_active
            inx
            cpx #MAX_NOTES
            bne check_notes_clear

            dec end_delay
            bne song_not_ended

            jsr show_results
            lda #STATE_RESULTS
            sta game_state

notes_still_active:
song_not_ended:
            rts

; ----------------------------------------------------------------------------
; Initialize Song
; ----------------------------------------------------------------------------

init_song:
            lda #<song_data
            sta song_pos
            lda #>song_data
            sta song_pos_hi

            lda #0
            sta frame_count
            sta beat_count
            sta song_beat
            sta border_flash
            sta song_ended

            lda #END_DELAY_FRAMES
            sta end_delay

            jsr display_progress
            rts

; ----------------------------------------------------------------------------
; Advance Song
; ----------------------------------------------------------------------------

advance_song:
            lda song_ended
            bne advance_done

            inc beat_count
            inc song_beat

            lda song_beat
            cmp #SONG_LENGTH
            bcc song_continues

            lda #1
            sta song_ended

song_continues:
            jsr display_progress

advance_done:
            rts

; ----------------------------------------------------------------------------
; Display Progress
; ----------------------------------------------------------------------------

display_progress:
            lda song_beat
            lsr
            lsr
            sta temp_progress

            ldx #0
            lda temp_progress
            beq draw_empty_progress

draw_full_progress:
            lda #CHAR_BAR_FULL
            sta SCREEN + (PROGRESS_ROW * 40) + 12,x
            lda #PROGRESS_COL
            sta COLRAM + (PROGRESS_ROW * 40) + 12,x
            inx
            cpx temp_progress
            bne draw_full_progress

draw_empty_progress:
            cpx #PROGRESS_WIDTH
            beq progress_done
            lda #CHAR_BAR_EMPTY
            sta SCREEN + (PROGRESS_ROW * 40) + 12,x
            lda #11
            sta COLRAM + (PROGRESS_ROW * 40) + 12,x
            inx
            jmp draw_empty_progress

progress_done:
            rts

temp_progress: !byte 0

; ----------------------------------------------------------------------------
; Get Multiplier
; ----------------------------------------------------------------------------

get_multiplier:
            lda combo
            cmp #COMBO_TIER_4
            bcs mult_4x
            cmp #COMBO_TIER_3
            bcs mult_3x
            cmp #COMBO_TIER_2
            bcs mult_2x

            lda #1
            rts

mult_2x:
            lda #2
            rts

mult_3x:
            lda #3
            rts

mult_4x:
            lda #4
            rts

; ----------------------------------------------------------------------------
; Display Combo
; ----------------------------------------------------------------------------

display_combo:
            ldx #0
draw_combo_label:
            lda combo_label,x
            beq draw_combo_value
            sta SCREEN + (COMBO_ROW * 40) + 12,x
            lda #11
            sta COLRAM + (COMBO_ROW * 40) + 12,x
            inx
            jmp draw_combo_label

draw_combo_value:
            lda combo

            ldx #0
combo_div_100:
            cmp #100
            bcc combo_done_100
            sec
            sbc #100
            inx
            jmp combo_div_100
combo_done_100:
            pha
            txa
            ora #$30
            sta SCREEN + (COMBO_ROW * 40) + 18
            pla

            ldx #0
combo_div_10:
            cmp #10
            bcc combo_done_10
            sec
            sbc #10
            inx
            jmp combo_div_10
combo_done_10:
            pha
            txa
            ora #$30
            sta SCREEN + (COMBO_ROW * 40) + 19
            pla

            ora #$30
            sta SCREEN + (COMBO_ROW * 40) + 20

            jsr get_multiplier
            cmp #4
            beq combo_col_4x
            cmp #3
            beq combo_col_3x
            cmp #2
            beq combo_col_2x

            lda #11
            jmp set_combo_col

combo_col_2x:
            lda #7
            jmp set_combo_col

combo_col_3x:
            lda #5
            jmp set_combo_col

combo_col_4x:
            lda #1

set_combo_col:
            sta COLRAM + (COMBO_ROW * 40) + 18
            sta COLRAM + (COMBO_ROW * 40) + 19
            sta COLRAM + (COMBO_ROW * 40) + 20

            jsr get_multiplier
            ora #$30
            sta SCREEN + (COMBO_ROW * 40) + 22
            lda #$18
            sta SCREEN + (COMBO_ROW * 40) + 23

            jsr get_multiplier
            cmp #4
            beq mult_col_4x
            cmp #3
            beq mult_col_3x
            cmp #2
            beq mult_col_2x

            lda #11
            jmp set_mult_col

mult_col_2x:
            lda #7
            jmp set_mult_col

mult_col_3x:
            lda #5
            jmp set_mult_col

mult_col_4x:
            lda #1

set_mult_col:
            sta COLRAM + (COMBO_ROW * 40) + 22
            sta COLRAM + (COMBO_ROW * 40) + 23

            rts

combo_label:
            !scr "combo:"
            !byte 0

; ----------------------------------------------------------------------------
; Increment Combo
; ----------------------------------------------------------------------------

increment_combo:
            inc combo

            lda combo
            cmp max_combo
            bcc combo_not_max
            sta max_combo
combo_not_max:

            jsr display_combo
            rts

; ----------------------------------------------------------------------------
; Break Combo
; ----------------------------------------------------------------------------

break_combo:
            lda combo
            beq combo_already_zero

            lda #0
            sta combo
            jsr display_combo

combo_already_zero:
            rts

; ----------------------------------------------------------------------------
; Show Results Screen
; ----------------------------------------------------------------------------

show_results:
            ldx #0
            lda #CHAR_SPACE
clear_for_results:
            sta SCREEN,x
            sta SCREEN+$100,x
            sta SCREEN+$200,x
            sta SCREEN+$2E8,x
            inx
            bne clear_for_results

            ldx #0
draw_results_title:
            lda results_title,x
            beq draw_results_title_done
            sta SCREEN + (3 * 40) + 14,x
            lda #1
            sta COLRAM + (3 * 40) + 14,x
            inx
            jmp draw_results_title
draw_results_title_done:

            ldx #0
draw_final_score_label:
            lda final_score_label,x
            beq draw_final_score_done
            sta SCREEN + (6 * 40) + 10,x
            lda #7
            sta COLRAM + (6 * 40) + 10,x
            inx
            jmp draw_final_score_label
draw_final_score_done:
            jsr display_final_score

            ldx #0
draw_perfects_label:
            lda perfects_label,x
            beq draw_perfects_done
            sta SCREEN + (8 * 40) + 10,x
            lda #1
            sta COLRAM + (8 * 40) + 10,x
            inx
            jmp draw_perfects_label
draw_perfects_done:
            lda perfect_count
            jsr display_stat_at_8

            ldx #0
draw_goods_label:
            lda goods_label,x
            beq draw_goods_done
            sta SCREEN + (9 * 40) + 10,x
            lda #7
            sta COLRAM + (9 * 40) + 10,x
            inx
            jmp draw_goods_label
draw_goods_done:
            lda good_count
            jsr display_stat_at_9

            ldx #0
draw_misses_label:
            lda misses_label,x
            beq draw_misses_done
            sta SCREEN + (10 * 40) + 10,x
            lda #2
            sta COLRAM + (10 * 40) + 10,x
            inx
            jmp draw_misses_label
draw_misses_done:
            lda miss_count
            jsr display_stat_at_10

            ldx #0
draw_max_combo_label:
            lda max_combo_label,x
            beq draw_max_combo_done
            sta SCREEN + (12 * 40) + 10,x
            lda #13
            sta COLRAM + (12 * 40) + 10,x
            inx
            jmp draw_max_combo_label
draw_max_combo_done:
            lda max_combo
            jsr display_stat_at_12

            ldx #0
draw_accuracy_label:
            lda accuracy_label,x
            beq draw_accuracy_done
            sta SCREEN + (14 * 40) + 10,x
            lda #5
            sta COLRAM + (14 * 40) + 10,x
            inx
            jmp draw_accuracy_label
draw_accuracy_done:
            jsr calculate_accuracy
            jsr display_accuracy

            ldx #0
draw_press_key:
            lda press_fire_results,x
            beq draw_press_key_done
            sta SCREEN + (18 * 40) + 9,x
            lda #7
            sta COLRAM + (18 * 40) + 9,x
            inx
            jmp draw_press_key
draw_press_key_done:

            lda #5
            sta BORDER

            rts

results_title:
            !scr "song complete!"
            !byte 0

final_score_label:
            !scr "final score:"
            !byte 0

perfects_label:
            !scr "perfects:"
            !byte 0

goods_label:
            !scr "goods:"
            !byte 0

misses_label:
            !scr "misses:"
            !byte 0

max_combo_label:
            !scr "max combo:"
            !byte 0

accuracy_label:
            !scr "accuracy:"
            !byte 0

press_fire_results:
            !scr "press fire for title"
            !byte 0

; ----------------------------------------------------------------------------
; Display Final Score
; ----------------------------------------------------------------------------

display_final_score:
            lda score_lo
            sta work_lo
            lda score_hi
            sta work_hi

            ldx #0
fs_div_10000:
            lda work_lo
            sec
            sbc #<10000
            tay
            lda work_hi
            sbc #>10000
            bcc fs_done_10000
            sta work_hi
            sty work_lo
            inx
            jmp fs_div_10000
fs_done_10000:
            txa
            ora #$30
            sta SCREEN + (6 * 40) + 23

            ldx #0
fs_div_1000:
            lda work_lo
            sec
            sbc #<1000
            tay
            lda work_hi
            sbc #>1000
            bcc fs_done_1000
            sta work_hi
            sty work_lo
            inx
            jmp fs_div_1000
fs_done_1000:
            txa
            ora #$30
            sta SCREEN + (6 * 40) + 24

            ldx #0
fs_div_100:
            lda work_lo
            sec
            sbc #100
            bcc fs_done_100
            sta work_lo
            inx
            jmp fs_div_100
fs_done_100:
            txa
            ora #$30
            sta SCREEN + (6 * 40) + 25

            ldx #0
fs_div_10:
            lda work_lo
            sec
            sbc #10
            bcc fs_done_10
            sta work_lo
            inx
            jmp fs_div_10
fs_done_10:
            txa
            ora #$30
            sta SCREEN + (6 * 40) + 26

            lda work_lo
            ora #$30
            sta SCREEN + (6 * 40) + 27

            lda #7
            sta COLRAM + (6 * 40) + 23
            sta COLRAM + (6 * 40) + 24
            sta COLRAM + (6 * 40) + 25
            sta COLRAM + (6 * 40) + 26
            sta COLRAM + (6 * 40) + 27

            rts

; ----------------------------------------------------------------------------
; Display Stats
; ----------------------------------------------------------------------------

display_stat_at_8:
            ldx #0
stat8_div:
            cmp #10
            bcc stat8_done
            sec
            sbc #10
            inx
            jmp stat8_div
stat8_done:
            pha
            txa
            ora #$30
            sta SCREEN + (8 * 40) + 23
            pla
            ora #$30
            sta SCREEN + (8 * 40) + 24
            lda #1
            sta COLRAM + (8 * 40) + 23
            sta COLRAM + (8 * 40) + 24
            rts

display_stat_at_9:
            ldx #0
stat9_div:
            cmp #10
            bcc stat9_done
            sec
            sbc #10
            inx
            jmp stat9_div
stat9_done:
            pha
            txa
            ora #$30
            sta SCREEN + (9 * 40) + 23
            pla
            ora #$30
            sta SCREEN + (9 * 40) + 24
            lda #7
            sta COLRAM + (9 * 40) + 23
            sta COLRAM + (9 * 40) + 24
            rts

display_stat_at_10:
            ldx #0
stat10_div:
            cmp #10
            bcc stat10_done
            sec
            sbc #10
            inx
            jmp stat10_div
stat10_done:
            pha
            txa
            ora #$30
            sta SCREEN + (10 * 40) + 23
            pla
            ora #$30
            sta SCREEN + (10 * 40) + 24
            lda #2
            sta COLRAM + (10 * 40) + 23
            sta COLRAM + (10 * 40) + 24
            rts

display_stat_at_12:
            ldx #0
stat12_div:
            cmp #10
            bcc stat12_done
            sec
            sbc #10
            inx
            jmp stat12_div
stat12_done:
            pha
            txa
            ora #$30
            sta SCREEN + (12 * 40) + 23
            pla
            ora #$30
            sta SCREEN + (12 * 40) + 24
            lda #13
            sta COLRAM + (12 * 40) + 23
            sta COLRAM + (12 * 40) + 24
            rts

; ----------------------------------------------------------------------------
; Calculate Accuracy
; ----------------------------------------------------------------------------

calculate_accuracy:
            lda perfect_count
            clc
            adc good_count
            sta total_hits

            clc
            adc miss_count
            sta total_notes

            beq accuracy_zero

            lda total_hits
            sta dividend_lo
            lda #0
            sta dividend_hi

            ldx #100
mult_loop:
            dex
            beq mult_done
            lda dividend_lo
            clc
            adc total_hits
            sta dividend_lo
            lda dividend_hi
            adc #0
            sta dividend_hi
            jmp mult_loop
mult_done:

            lda #0
            sta accuracy
div_loop:
            lda dividend_lo
            sec
            sbc total_notes
            tay
            lda dividend_hi
            sbc #0
            bcc div_done
            sta dividend_hi
            sty dividend_lo
            inc accuracy
            jmp div_loop
div_done:
            rts

accuracy_zero:
            lda #0
            sta accuracy
            rts

total_hits:   !byte 0
total_notes:  !byte 0
dividend_lo:  !byte 0
dividend_hi:  !byte 0
accuracy:     !byte 0

; ----------------------------------------------------------------------------
; Display Accuracy
; ----------------------------------------------------------------------------

display_accuracy:
            lda accuracy

            ldx #0
acc_div_100:
            cmp #100
            bcc acc_done_100
            sec
            sbc #100
            inx
            jmp acc_div_100
acc_done_100:
            pha
            txa
            ora #$30
            sta SCREEN + (14 * 40) + 23
            pla

            ldx #0
acc_div_10:
            cmp #10
            bcc acc_done_10
            sec
            sbc #10
            inx
            jmp acc_div_10
acc_done_10:
            pha
            txa
            ora #$30
            sta SCREEN + (14 * 40) + 24
            pla

            ora #$30
            sta SCREEN + (14 * 40) + 25

            lda #$25
            sta SCREEN + (14 * 40) + 26

            lda #5
            sta COLRAM + (14 * 40) + 23
            sta COLRAM + (14 * 40) + 24
            sta COLRAM + (14 * 40) + 25
            sta COLRAM + (14 * 40) + 26

            rts

; ----------------------------------------------------------------------------
; Copy Character Set
; ----------------------------------------------------------------------------

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:
            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

            lda #%00000000
            sta CHARSET + (CHAR_TRACK * 8) + 0
            sta CHARSET + (CHAR_TRACK * 8) + 1
            sta CHARSET + (CHAR_TRACK * 8) + 2
            lda #%11111111
            sta CHARSET + (CHAR_TRACK * 8) + 3
            sta CHARSET + (CHAR_TRACK * 8) + 4
            lda #%00000000
            sta CHARSET + (CHAR_TRACK * 8) + 5
            sta CHARSET + (CHAR_TRACK * 8) + 6
            sta CHARSET + (CHAR_TRACK * 8) + 7

            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

            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

            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
            sta perfect_count
            sta good_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
            sta note_freq,x
            dex
            bpl init_notes_loop
            rts

; ----------------------------------------------------------------------------
; Check Spawn Note
; ----------------------------------------------------------------------------

check_spawn_note:
            lda song_ended
            bne spawn_done_early

            ldy #0

spawn_check_loop:
            lda (song_pos),y
            cmp #$FF
            beq spawn_song_end

            cmp beat_count
            beq spawn_match
            bcs spawn_done_early

            jmp spawn_advance

spawn_match:
            iny
            lda (song_pos),y
            sta temp_track
            iny
            lda (song_pos),y
            pha
            lda temp_track
            jsr spawn_note_with_freq
            pla
            dey
            dey

spawn_advance:
            lda song_pos
            clc
            adc #3
            sta song_pos
            lda song_pos_hi
            adc #0
            sta song_pos_hi
            jmp spawn_check_loop

spawn_song_end:
            lda #1
            sta song_ended

spawn_done_early:
            rts

; ----------------------------------------------------------------------------
; Spawn Note With Frequency
; ----------------------------------------------------------------------------

spawn_note_with_freq:
            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

            tsx
            lda $0103,x
            sta note_freq,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
            jsr decrease_health
            jsr break_combo

            rts

; ----------------------------------------------------------------------------
; Decrease Health
; ----------------------------------------------------------------------------

decrease_health:
            lda health
            sec
            sbc #HEALTH_MISS
            bcc health_zero
            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
; ----------------------------------------------------------------------------

increase_health:
            clc
            adc health
            cmp #HEALTH_MAX
            bcc health_ok
            lda #HEALTH_MAX
health_ok:
            sta health
            jsr display_health
            rts

; ----------------------------------------------------------------------------
; Check Game Over
; ----------------------------------------------------------------------------

check_game_over:
            lda health
            bne not_game_over

            lda #STATE_GAMEOVER
            sta game_state
            jsr show_game_over

not_game_over:
            rts

; ----------------------------------------------------------------------------
; Show Game Over
; ----------------------------------------------------------------------------

show_game_over:
            ; Clear screen for game over display
            ldx #0
            lda #CHAR_SPACE
clear_gameover:
            sta SCREEN,x
            sta SCREEN+$100,x
            sta SCREEN+$200,x
            sta SCREEN+$2E8,x
            inx
            bne clear_gameover

            ; Draw "GAME OVER" in red
            ldx #0
game_over_loop:
            lda game_over_text,x
            beq game_over_text_done
            sta SCREEN + (6 * 40) + 15,x
            lda #2                  ; Red for failure
            sta COLRAM + (6 * 40) + 15,x
            inx
            jmp game_over_loop
game_over_text_done:

            ; Draw "HEALTH DEPLETED"
            ldx #0
draw_depleted:
            lda depleted_text,x
            beq draw_depleted_done
            sta SCREEN + (8 * 40) + 12,x
            lda #10                 ; Light red
            sta COLRAM + (8 * 40) + 12,x
            inx
            jmp draw_depleted
draw_depleted_done:

            ; Show score achieved
            ldx #0
draw_go_score_label:
            lda go_score_label,x
            beq draw_go_score_done
            sta SCREEN + (12 * 40) + 11,x
            lda #7
            sta COLRAM + (12 * 40) + 11,x
            inx
            jmp draw_go_score_label
draw_go_score_done:
            jsr display_gameover_score

            ; Show notes hit
            ldx #0
draw_go_notes_label:
            lda go_notes_label,x
            beq draw_go_notes_done
            sta SCREEN + (14 * 40) + 11,x
            lda #11
            sta COLRAM + (14 * 40) + 11,x
            inx
            jmp draw_go_notes_label
draw_go_notes_done:
            lda perfect_count
            clc
            adc good_count
            jsr display_go_stat

            ; "PRESS FIRE FOR TITLE"
            ldx #0
game_over_press:
            lda press_fire_gameover,x
            beq game_over_done
            sta SCREEN + (18 * 40) + 10,x
            lda #7                  ; Yellow for action
            sta COLRAM + (18 * 40) + 10,x
            inx
            jmp game_over_press

game_over_done:
            lda #2                  ; Red border
            sta BORDER
            rts

game_over_text:
            !scr "game over"
            !byte 0

depleted_text:
            !scr "health depleted"
            !byte 0

go_score_label:
            !scr "score achieved:"
            !byte 0

go_notes_label:
            !scr "notes hit:"
            !byte 0

press_fire_gameover:
            !scr "press fire for title"
            !byte 0

; Display gameover score (row 12)
display_gameover_score:
            lda score_lo
            sta work_lo
            lda score_hi
            sta work_hi

            ldx #0
go_div_10000:
            lda work_lo
            sec
            sbc #<10000
            tay
            lda work_hi
            sbc #>10000
            bcc go_done_10000
            sta work_hi
            sty work_lo
            inx
            jmp go_div_10000
go_done_10000:
            txa
            ora #$30
            sta SCREEN + (12 * 40) + 27

            ldx #0
go_div_1000:
            lda work_lo
            sec
            sbc #<1000
            tay
            lda work_hi
            sbc #>1000
            bcc go_done_1000
            sta work_hi
            sty work_lo
            inx
            jmp go_div_1000
go_done_1000:
            txa
            ora #$30
            sta SCREEN + (12 * 40) + 28

            ldx #0
go_div_100:
            lda work_lo
            sec
            sbc #100
            bcc go_done_100
            sta work_lo
            inx
            jmp go_div_100
go_done_100:
            txa
            ora #$30
            sta SCREEN + (12 * 40) + 29

            ldx #0
go_div_10:
            lda work_lo
            sec
            sbc #10
            bcc go_done_10
            sta work_lo
            inx
            jmp go_div_10
go_done_10:
            txa
            ora #$30
            sta SCREEN + (12 * 40) + 30

            lda work_lo
            ora #$30
            sta SCREEN + (12 * 40) + 31

            lda #7
            sta COLRAM + (12 * 40) + 27
            sta COLRAM + (12 * 40) + 28
            sta COLRAM + (12 * 40) + 29
            sta COLRAM + (12 * 40) + 30
            sta COLRAM + (12 * 40) + 31
            rts

; Display notes hit stat at row 14
display_go_stat:
            ldx #0
go_stat_div:
            cmp #10
            bcc go_stat_done
            sec
            sbc #10
            inx
            jmp go_stat_div
go_stat_done:
            pha
            txa
            ora #$30
            sta SCREEN + (14 * 40) + 27
            pla
            ora #$30
            sta SCREEN + (14 * 40) + 28
            lda #11
            sta COLRAM + (14 * 40) + 27
            sta COLRAM + (14 * 40) + 28
            rts

; ----------------------------------------------------------------------------
; Display Health
; ----------------------------------------------------------------------------

display_health:
            lda health
            lsr
            lsr
            lsr
            sta temp_health

            ldx #0
            lda temp_health
            beq draw_empty_bars

draw_full_bars:
            lda #CHAR_BAR_FULL
            sta SCREEN + (HEALTH_ROW * 40) + 12,x
            lda #HEALTH_COL
            sta COLRAM + (HEALTH_ROW * 40) + 12,x
            inx
            cpx temp_health
            bne draw_full_bars

draw_empty_bars:
            cpx #8
            beq health_done
            lda #CHAR_BAR_EMPTY
            sta SCREEN + (HEALTH_ROW * 40) + 12,x
            lda #11
            sta COLRAM + (HEALTH_ROW * 40) + 12,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

            ldx #0
draw_t2:
            sta SCREEN + (TRACK2_ROW * 40),x
            inx
            cpx #38
            bne draw_t2

            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:
            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:

            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:

            ldx #0
draw_title_game:
            lda title_game,x
            beq draw_title_game_done
            sta SCREEN + 27,x
            lda #1
            sta COLRAM + 27,x
            inx
            bne draw_title_game
draw_title_game_done:

            ldx #0
draw_health_label:
            lda health_label,x
            beq draw_health_label_done
            sta SCREEN + (HEALTH_ROW * 40) + 4,x
            lda #5
            sta COLRAM + (HEALTH_ROW * 40) + 4,x
            inx
            bne draw_health_label
draw_health_label_done:

            ldx #0
draw_progress_label:
            lda progress_label,x
            beq draw_progress_label_done
            sta SCREEN + (PROGRESS_ROW * 40) + 4,x
            lda #3
            sta COLRAM + (PROGRESS_ROW * 40) + 4,x
            inx
            bne draw_progress_label
draw_progress_label_done:

            lda #$1A
            sta SCREEN + (TRACK1_ROW * 40)
            lda #TRACK1_NOTE_COL
            sta COLRAM + (TRACK1_ROW * 40)

            lda #$18
            sta SCREEN + (TRACK2_ROW * 40)
            lda #TRACK2_NOTE_COL
            sta COLRAM + (TRACK2_ROW * 40)

            lda #$03
            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_game:
            !scr "sid symphony"
            !byte 0

health_label:
            !scr "health:"
            !byte 0

progress_label:
            !scr "song:"
            !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_note
            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_note
            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_note
            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

            lda note_freq,x
            sta hit_note_freq

            lda note_col,x
            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:
            jsr increment_combo

            lda hit_quality
            cmp #2
            beq award_perfect

            lda #GOOD_SCORE
            jsr apply_multiplier
            jsr add_score

            inc good_count

            lda #GOOD_COL
            sta BORDER
            lda #4
            sta border_flash

            lda #HEALTH_GOOD
            jsr increase_health

            jmp award_done

award_perfect:
            lda #PERFECT_SCORE
            jsr apply_multiplier
            jsr add_score

            inc perfect_count

            lda #PERFECT_COL
            sta BORDER
            lda #6
            sta border_flash

            lda #HEALTH_PERFECT
            jsr increase_health

award_done:
            jsr display_score
            rts

; ----------------------------------------------------------------------------
; Apply Multiplier
; ----------------------------------------------------------------------------

apply_multiplier:
            sta base_score
            jsr get_multiplier
            sta current_mult

            lda base_score
            sta score_add_lo
            lda #0
            sta score_add_hi

            lda current_mult
            cmp #1
            beq mult_done_apply

            dec current_mult
mult_add_loop:
            lda score_add_lo
            clc
            adc base_score
            sta score_add_lo
            lda score_add_hi
            adc #0
            sta score_add_hi
            dec current_mult
            bne mult_add_loop

mult_done_apply:
            rts

base_score:    !byte 0
current_mult:  !byte 0
score_add_lo:  !byte 0
score_add_hi:  !byte 0

; ----------------------------------------------------------------------------
; Add Score
; ----------------------------------------------------------------------------

add_score:
            lda score_lo
            clc
            adc score_add_lo
            sta score_lo
            lda score_hi
            adc score_add_hi
            sta score_hi
            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_note:
            lda #0
            sta SID_V1_FREQ_LO
            lda hit_note_freq
            sta SID_V1_FREQ_HI
            lda #VOICE1_WAVE
            ora #$01
            sta SID_V1_CTRL
            rts

play_voice2_note:
            lda #0
            sta SID_V2_FREQ_LO
            lda hit_note_freq
            sta SID_V2_FREQ_HI
            lda #VOICE2_WAVE
            ora #$01
            sta SID_V2_CTRL
            rts

play_voice3_note:
            lda #0
            sta SID_V3_FREQ_LO
            lda hit_note_freq
            sta SID_V3_FREQ_HI
            lda #VOICE3_WAVE
            ora #$01
            sta SID_V3_CTRL
            rts

; ----------------------------------------------------------------------------
; Flash Tracks
; ----------------------------------------------------------------------------

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, $47
            !byte 2, 2, $2C
            !byte 4, 3, $11

            !byte 8, 1, $3B
            !byte 10, 2, $27
            !byte 12, 3, $13

            !byte 16, 1, $35
            !byte 17, 2, $2C
            !byte 18, 1, $3B
            !byte 20, 3, $16

            !byte 24, 1, $47
            !byte 26, 2, $35
            !byte 28, 3, $11

            !byte 32, 2, $2F
            !byte 34, 1, $4F
            !byte 36, 3, $17

            !byte 40, 1, $58
            !byte 42, 2, $2C
            !byte 44, 3, $11
            !byte 46, 2, $27

            !byte 48, 1, $6A
            !byte 49, 2, $35
            !byte 50, 1, $58
            !byte 52, 3, $1A
            !byte 54, 2, $2F

            !byte 56, 1, $47
            !byte 58, 2, $2C
            !byte 60, 3, $11
            !byte 62, 1, $35

            !byte $FF

; ----------------------------------------------------------------------------
; Note Arrays
; ----------------------------------------------------------------------------

note_track:
            !fill MAX_NOTES, 0

note_col:
            !fill MAX_NOTES, 0

note_freq:
            !fill MAX_NOTES, 0

; ----------------------------------------------------------------------------
; Game Variables
; ----------------------------------------------------------------------------

score_lo:     !byte 0
score_hi:     !byte 0
miss_count:   !byte 0
perfect_count: !byte 0
good_count:   !byte 0
health:       !byte 0
combo:        !byte 0
max_combo:    !byte 0

Try This: Retry Option

Add a quick retry option instead of returning to title:

update_gameover:
            ; Check fire for title
            lda CIA1_PRA
            and #$10
            beq go_to_title

            ; Check R key for retry
            lda #$FB
            sta CIA1_PRA
            lda CIA1_PRB
            and #$04            ; R key
            beq retry_game

            ; ... cleanup and return ...

retry_game:
            jsr init_game
            lda #STATE_PLAYING
            sta game_state
            rts

Quick retry keeps players in the flow.

Try This: Continue Counter

Show how many continues have been used:

continue_count: !byte 0

retry_game:
            inc continue_count
            ; ... draw continue count on gameplay screen ...

Some players want to see their full history.

What You’ve Learnt

  • Failure presentation - Dedicated screen for game over
  • Colour communication - Red for failure, green for success
  • Partial progress - Showing achievement before failure
  • State distinction - Visual language separating outcomes
  • Emotional design - Failure should feel different from success

What’s Next

In Unit 15, we’ll polish all the sound effects. Perfect hits will sound brighter than good hits, miss sounds will be harsh, and menu sounds will click satisfyingly.

What Changed

Unit 13 → Unit 14
+182-10
11 ; ============================================================================
2-; SID SYMPHONY - Unit 13: Title Screen
2+; SID SYMPHONY - Unit 14: Game Over Screen
33 ; ============================================================================
4-; The game now starts with a proper title screen. Press fire to play.
5-; Complete game flow: Title -> Playing -> Results -> Title.
4+; Improved game over screen when health depletes. Clear display showing
5+; failure distinctly from success. Score shown, red colour scheme.
66 ;
77 ; Controls: Z = Track 1 (high), X = Track 2 (mid), C = Track 3 (low)
88 ; Fire = Start game from title screen
...
15741574 ; ----------------------------------------------------------------------------
15751575
15761576 show_game_over:
1577+ ; Clear screen for game over display
1578+ ldx #0
1579+ lda #CHAR_SPACE
1580+clear_gameover:
1581+ sta SCREEN,x
1582+ sta SCREEN+$100,x
1583+ sta SCREEN+$200,x
1584+ sta SCREEN+$2E8,x
1585+ inx
1586+ bne clear_gameover
1587+
1588+ ; Draw "GAME OVER" in red
15771589 ldx #0
15781590 game_over_loop:
15791591 lda game_over_text,x
15801592 beq game_over_text_done
1581- sta SCREEN + (10 * 40) + 15,x
1582- lda #2
1583- sta COLRAM + (10 * 40) + 15,x
1593+ sta SCREEN + (6 * 40) + 15,x
1594+ lda #2 ; Red for failure
1595+ sta COLRAM + (6 * 40) + 15,x
15841596 inx
15851597 jmp game_over_loop
15861598 game_over_text_done:
1599+
1600+ ; Draw "HEALTH DEPLETED"
1601+ ldx #0
1602+draw_depleted:
1603+ lda depleted_text,x
1604+ beq draw_depleted_done
1605+ sta SCREEN + (8 * 40) + 12,x
1606+ lda #10 ; Light red
1607+ sta COLRAM + (8 * 40) + 12,x
1608+ inx
1609+ jmp draw_depleted
1610+draw_depleted_done:
1611+
1612+ ; Show score achieved
1613+ ldx #0
1614+draw_go_score_label:
1615+ lda go_score_label,x
1616+ beq draw_go_score_done
1617+ sta SCREEN + (12 * 40) + 11,x
1618+ lda #7
1619+ sta COLRAM + (12 * 40) + 11,x
1620+ inx
1621+ jmp draw_go_score_label
1622+draw_go_score_done:
1623+ jsr display_gameover_score
1624+
1625+ ; Show notes hit
1626+ ldx #0
1627+draw_go_notes_label:
1628+ lda go_notes_label,x
1629+ beq draw_go_notes_done
1630+ sta SCREEN + (14 * 40) + 11,x
1631+ lda #11
1632+ sta COLRAM + (14 * 40) + 11,x
1633+ inx
1634+ jmp draw_go_notes_label
1635+draw_go_notes_done:
1636+ lda perfect_count
1637+ clc
1638+ adc good_count
1639+ jsr display_go_stat
15871640
1641+ ; "PRESS FIRE FOR TITLE"
15881642 ldx #0
15891643 game_over_press:
15901644 lda press_fire_gameover,x
15911645 beq game_over_done
1592- sta SCREEN + (14 * 40) + 9,x
1593- lda #7
1594- sta COLRAM + (14 * 40) + 9,x
1646+ sta SCREEN + (18 * 40) + 10,x
1647+ lda #7 ; Yellow for action
1648+ sta COLRAM + (18 * 40) + 10,x
15951649 inx
15961650 jmp game_over_press
15971651
15981652 game_over_done:
1599- lda #2
1653+ lda #2 ; Red border
16001654 sta BORDER
16011655 rts
16021656
16031657 game_over_text:
16041658 !scr "game over"
1659+ !byte 0
1660+
1661+depleted_text:
1662+ !scr "health depleted"
1663+ !byte 0
1664+
1665+go_score_label:
1666+ !scr "score achieved:"
1667+ !byte 0
1668+
1669+go_notes_label:
1670+ !scr "notes hit:"
16051671 !byte 0
16061672
16071673 press_fire_gameover:
16081674 !scr "press fire for title"
16091675 !byte 0
1676+
1677+; Display gameover score (row 12)
1678+display_gameover_score:
1679+ lda score_lo
1680+ sta work_lo
1681+ lda score_hi
1682+ sta work_hi
1683+
1684+ ldx #0
1685+go_div_10000:
1686+ lda work_lo
1687+ sec
1688+ sbc #<10000
1689+ tay
1690+ lda work_hi
1691+ sbc #>10000
1692+ bcc go_done_10000
1693+ sta work_hi
1694+ sty work_lo
1695+ inx
1696+ jmp go_div_10000
1697+go_done_10000:
1698+ txa
1699+ ora #$30
1700+ sta SCREEN + (12 * 40) + 27
1701+
1702+ ldx #0
1703+go_div_1000:
1704+ lda work_lo
1705+ sec
1706+ sbc #<1000
1707+ tay
1708+ lda work_hi
1709+ sbc #>1000
1710+ bcc go_done_1000
1711+ sta work_hi
1712+ sty work_lo
1713+ inx
1714+ jmp go_div_1000
1715+go_done_1000:
1716+ txa
1717+ ora #$30
1718+ sta SCREEN + (12 * 40) + 28
1719+
1720+ ldx #0
1721+go_div_100:
1722+ lda work_lo
1723+ sec
1724+ sbc #100
1725+ bcc go_done_100
1726+ sta work_lo
1727+ inx
1728+ jmp go_div_100
1729+go_done_100:
1730+ txa
1731+ ora #$30
1732+ sta SCREEN + (12 * 40) + 29
1733+
1734+ ldx #0
1735+go_div_10:
1736+ lda work_lo
1737+ sec
1738+ sbc #10
1739+ bcc go_done_10
1740+ sta work_lo
1741+ inx
1742+ jmp go_div_10
1743+go_done_10:
1744+ txa
1745+ ora #$30
1746+ sta SCREEN + (12 * 40) + 30
1747+
1748+ lda work_lo
1749+ ora #$30
1750+ sta SCREEN + (12 * 40) + 31
1751+
1752+ lda #7
1753+ sta COLRAM + (12 * 40) + 27
1754+ sta COLRAM + (12 * 40) + 28
1755+ sta COLRAM + (12 * 40) + 29
1756+ sta COLRAM + (12 * 40) + 30
1757+ sta COLRAM + (12 * 40) + 31
1758+ rts
1759+
1760+; Display notes hit stat at row 14
1761+display_go_stat:
1762+ ldx #0
1763+go_stat_div:
1764+ cmp #10
1765+ bcc go_stat_done
1766+ sec
1767+ sbc #10
1768+ inx
1769+ jmp go_stat_div
1770+go_stat_done:
1771+ pha
1772+ txa
1773+ ora #$30
1774+ sta SCREEN + (14 * 40) + 27
1775+ pla
1776+ ora #$30
1777+ sta SCREEN + (14 * 40) + 28
1778+ lda #11
1779+ sta COLRAM + (14 * 40) + 27
1780+ sta COLRAM + (14 * 40) + 28
1781+ rts
16101782
16111783 ; ----------------------------------------------------------------------------
16121784 ; Display Health