Pause

The Need to Stop

Life interrupts. The phone rings. Someone knocks. The player needs to look away. Without pause, these moments become failures — missed notes, lost progress, frustration.

Pause is respect. It says “take your time, we’ll wait.” A small feature with outsized impact on player experience.

A New State

We add a fifth game state:

; Game states
STATE_TITLE     = 0
STATE_PLAYING   = 1
STATE_GAMEOVER  = 2
STATE_VICTORY   = 3
STATE_PAUSED    = 4             ; Unit 15: Paused state

The main loop needs to handle this new state:

ml_not_gameover:
            cmp #STATE_VICTORY
            bne ml_not_victory
            jsr update_endscreen
            jmp main_loop
ml_not_victory:
            ; STATE_PAUSED (Unit 15)
            jsr update_paused
            jmp main_loop

Entering Pause

At the start of the game update, we check for the P key. If pressed, we silence audio, show the pause text, and switch states:

update_game:
            ; --- Check for pause key (Unit 15) ---
            jsr check_p_key
            ldx key_p_was
            sta key_p_was
            cpx #$00
            bne ug_no_pause
            cmp #$01
            bne ug_no_pause
            ; P just pressed - pause game
            jsr silence_all
            jsr draw_paused_text
            lda #STATE_PAUSED
            sta game_state
            rts
ug_no_pause:

The early rts is important — we exit immediately after pausing. No further game logic runs.

The Pause Loop

While paused, we do almost nothing. Just wait for P to be pressed again:

update_paused:
            ; Check for P key to unpause
            jsr check_p_key
            ldx key_p_was
            sta key_p_was
            cpx #$00
            bne up_done
            cmp #$01
            bne up_done
            ; P just pressed - unpause
            jsr erase_paused_text
            lda #STATE_PLAYING
            sta game_state
up_done:
            rts

This is the same edge-detection pattern we use for all keys — track the previous state to detect transitions, not held keys.

Reading the P Key

The C64 keyboard matrix puts P on row 5 (bit 5), column 1 (bit 1):

check_p_key:
            lda #%11011111              ; Row 5 (bit 5)
            sta CIA1_PRA
            lda CIA1_PRB
            and #%00000010              ; Column 1 (P)
            bne cp_not
            lda #$01
            rts
cp_not:
            lda #$00
            rts

Visual Feedback

Players need to know they’re paused. We draw “PAUSED” in the centre of the screen:

PAUSE_ROW   = 11
PAUSE_COL   = 17

draw_paused_text:
            ldx #$00
dpt_loop:
            lda paused_text,x
            beq dpt_done
            sta SCREEN + (PAUSE_ROW * 40) + PAUSE_COL,x
            lda #COL_YELLOW
            sta COLOUR + (PAUSE_ROW * 40) + PAUSE_COL,x
            inx
            bne dpt_loop
dpt_done:
            rts

erase_paused_text:
            ldx #$00
ept_loop:
            cpx #6                  ; "PAUSED" is 6 characters
            bcs ept_done
            lda #$20                ; Space
            sta SCREEN + (PAUSE_ROW * 40) + PAUSE_COL,x
            lda #$00
            sta COLOUR + (PAUSE_ROW * 40) + PAUSE_COL,x
            inx
            bne ept_loop
ept_done:
            rts

Yellow stands out against the game’s cyan and black palette. The text appears on row 11 — between the tracks, clearly visible but not obscuring gameplay elements.

What Pause Preserves

When we pause, everything freezes in place:

• Note positions: Notes stay where they are
• Score and streak: Progress is preserved
• Multiplier: No penalty for pausing
• Crowd meter: Doesn’t decay
• Song position: Resumes from the same beat

We achieve this by simply not calling any update routines while paused. The game state variables persist unchanged.

What Pause Stops

We explicitly silence audio:

            jsr silence_all

Without this, any playing notes would sustain forever. The silence_all routine gates off all three voices.

Design Decisions

Why P for pause? It’s intuitive (P for Pause) and not used for gameplay. Space is taken by the title screen, X/C/V are gameplay keys.

Why not pause on any key? Accidental pauses frustrate players. A dedicated key means intentional pauses only.

Why not dim the screen? Complexity without benefit. The “PAUSED” text is clear enough. Adding screen effects would require saving and restoring colour memory — more code for marginal gain.

What’s Next

The game is feature-complete. In Unit 16, we do a final polish pass — cleaning up code, optimising where it matters, and preparing the game for release.