Game 2Unit 17 of 191 hr learning time
Footsteps and Doors
The keep's events already sound — coins chime, victory flourishes, capture tolls. What's missing is the sound of the place itself. From the same one-bit beeper, add a footfall under every step and a falling creak at every door: sound as place, not as feedback.
89% of Shadowkeep
The keep looks like somewhere, and it plays — and it already makes sound when something happens: the coins chime as you lift them, the win flourishes, the Warden’s touch tolls you into stone. But those are the sounds of events. Put your ear to the keep between them and there’s nothing — no weight of stone underfoot, no groan of a door. This unit, the first of the Keep’s Voice sub-arc, gives the place a voice to match its events, and the tool is one already ringing in your game: the single-bit beeper. It rang the coin’s chime and the capture’s toll a few units ago; you made it sing across The Long Night — the dusk bells, the dawn phrase. Here it stops being an event and becomes ambience: a click of stone underfoot, the groan of a door on its hinge. Same one bit, a wholly different job.
What you’ll see (and hear) by the end
The screen is the same Hall as before — that’s the point. Nothing new is drawn. But now, as you walk, a soft low click falls under every footstep on the stone; and when you cross from one chamber to the next, a door groans downward on its hinges. The keep is heard as well as seen. (The stills can’t carry it — load it and walk.)
One bit, one tone (already ringing)
You know this driver — it is the same beep the coin’s chime and the capture’s toll already call. Take it as a reminder, not a lesson. The speaker is a single bit — bit 4 of port $FE; toggle it high, low, high, fast, and the cone makes a square wave. beep takes two numbers — B, how many cycles to play (the duration), and C, how long to wait between toggles (the pitch; a larger C waits longer, so the wave is slower and the note lower):
beep: ; already in the game — the chime and the toll use it
.bp_cycle:
ld a, %00010000 ; speaker bit high
out ($FE), a
; ... wait C, toggle low, wait C ... B cycles in all ...
retEverything new here is composition — choosing B and C to make the sounds the place makes, to sit alongside the sounds its events already make.
Two sounds about place
A footfall is short and low — a handful of cycles of a low tone, gone almost before you notice it:
sfx_step:
ld b, 5 ; very short
ld c, 90 ; low
call beep
retA door is a creak — not one pitch but a falling one. We start the delay small (higher) and let it grow (lower), a few cycles at each step, so the note groans downward like a heavy door swinging:
sfx_door:
ld c, 36 ; start higher
.sd_sweep:
ld b, 3
push bc
call beep
pop bc
inc c ; lower the pitch a touch
inc c
ld a, c
cp 130 ; until it has groaned right down
jr c, .sd_sweep
retThese aren’t “you pressed a key” beeps. They’re about the place: the weight of stone, the heaviness of a door. That distinction — sound as atmosphere, not as button-feedback — is the whole reason to bother.
Wiring it in
Two call sites, and that’s all. A footstep on every successful move, dropped in right after the thief is redrawn:
call draw_thief
call sfx_step ; <- the footfall
call check_exitAnd a creak the moment we pass through to another room, at the top of the room-transition path:
.enter:
call sfx_door ; <- the hinges
call draw_room
; ...Walk, and you hear yourself. Cross a threshold, and the door answers.
Milestone — give the keep an ambient voice
The beep your chime and toll already use gets two more voices: sfx_step, a short
low blip, and sfx_door, a downward pitch-sweep for a falling creak. Two call sites
wire them in — a footfall after every successful move, a creak the moment the thief
passes through a doorway. The screen never changes; the diff is two small routines
and two hooks.
Step 1: a footfall and a door creak, on the beeper already in the game
+27-1
| 1 | 1 | ; Shadowkeep — Unit 17: Footsteps and Doors | |
| 2 | 2 | ; Cumulative build; every step runs on its own. Narrative: the unit page. | |
| 3 | - | ; step-00 = Unit 16's end: the game sounds its events, but the keep is otherwise silent. | |
| 3 | + | ; step-01 gives the keep its ambient voice — a footfall per step, a creak per door. | |
| 4 | 4 | | |
| 5 | 5 | org 32768 | |
| 6 | 6 | | |
| ... | |||
| 407 | 407 | call collect_gold ; the new cell might be gold — lift it first | |
| 408 | 408 | call save_under | |
| 409 | 409 | call draw_thief | |
| 410 | + | call sfx_step | |
| 410 | 411 | call check_exit | |
| 411 | 412 | ret | |
| 412 | 413 | | |
| ... | |||
| 472 | 473 | ld a, 1 | |
| 473 | 474 | ld (thief_row), a | |
| 474 | 475 | .enter: | |
| 476 | + | call sfx_door | |
| 475 | 477 | call draw_room | |
| 476 | 478 | call save_under | |
| 477 | 479 | call draw_thief | |
| ... | |||
| 777 | 779 | call beep | |
| 778 | 780 | ld b, 8 | |
| 779 | 781 | ld c, 14 | |
| 782 | + | call beep | |
| 783 | + | ret | |
| 784 | + | | |
| 785 | + | ; sfx_step — a footfall: short and low, gone almost before you notice it. Played | |
| 786 | + | ; under every successful move. | |
| 787 | + | sfx_step: | |
| 788 | + | ld b, 5 | |
| 789 | + | ld c, 90 | |
| 790 | + | call beep | |
| 791 | + | ret | |
| 792 | + | | |
| 793 | + | ; sfx_door — a creak: a tone that falls in pitch as it plays, so the note groans | |
| 794 | + | ; downward — a heavy door swinging on its hinges. | |
| 795 | + | sfx_door: | |
| 796 | + | ld c, 36 ; start higher | |
| 797 | + | .sd_sweep: | |
| 798 | + | ld b, 3 | |
| 799 | + | push bc | |
| 780 | 800 | call beep | |
| 801 | + | pop bc | |
| 802 | + | inc c ; lower the pitch a little | |
| 803 | + | inc c | |
| 804 | + | ld a, c | |
| 805 | + | cp 130 ; until it has groaned down low | |
| 806 | + | jr c, .sd_sweep | |
| 781 | 807 | ret | |
| 782 | 808 | | |
| 783 | 809 | gold_tile: |
The complete program
; Shadowkeep — Unit 17: Footsteps and Doors
; Cumulative build; every step runs on its own. Narrative: the unit page.
; step-01 gives the keep its ambient voice — a footfall per step, a creak per door.
org 32768
WALL_ATTR equ %01001000
FLOOR_ATTR equ %00001000
MARK_ATTR equ %00001111
TORCH_ATTR equ %01001110 ; BRIGHT, blue paper, yellow ink — a lit sconce
STATUE_ATTR equ %01001111 ; BRIGHT white on blue — pale stone (solid)
BANNER_ATTR equ %01001011 ; BRIGHT magenta on blue — a hanging (solid)
RUBBLE_ATTR equ %00001000 ; dim, like floor — walkable broken stone
MAX_SHADE equ 4
MAX_TORCHES equ 4
THIEF equ %01001010
GOLD_ATTR equ %00000110 ; yellow ink, no BRIGHT -> walkable gold
TOTAL_GOLD equ 6
WARDEN equ %01000101 ; BRIGHT cyan on black — the sentinel
WARDEN_COL0 equ 26 ; the Hall's gold column
WARDEN_ROW0 equ 11
WARDEN_SPEED equ 10 ; frames between patrol steps
WARDEN_GATHER equ 50 ; a beat before it begins to move
AXIS_HORIZ equ 0 ; the Warden varies its column (walks a row)
AXIS_VERT equ 1 ; the Warden varies its row (walks a column)
WALL_BIT equ 6
START_COL equ 15
START_ROW equ 11
NO_EXIT equ $FF
KEYS_OP equ $DFFE
KEYS_Q equ $FBFE
KEYS_A equ $FDFE
KEYS_SPACE equ $7FFE
start:
ld a, 0
out ($FE), a
im 1
; --- TITLE -> PLAY -> WIN -> TITLE ------------------------------------------
main_title:
call show_title ; returns (interrupts off) when SPACE pressed
call new_game ; reset the keep, place the gold, draw
ei
.game_loop:
halt
ld a, (won)
or a
jr nz, .won
call player_step
call warden_step ; every room has its Warden now
ld a, (caught)
or a
jr nz, .lost
call mark_step
jr .game_loop
.lost:
call show_lose ; "THE KEEP SLEEPS", the sting, wait for SPACE
jr main_title
.won:
call show_win ; "THE KEEP STANDS", flourish, wait for SPACE
jr main_title ; round again
; new_game — copy the room templates back into working state (so collected gold
; returns), reset the thief, the gold counter and the win flag, draw the keep.
new_game:
ld hl, room0_template
ld de, room0_state
ld bc, 768
ldir
ld hl, room1_template
ld de, room1_state
ld bc, 768
ldir
ld hl, room2_template
ld de, room2_state
ld bc, 768
ldir
xor a
ld (current_room), a
ld (won), a
ld (caught), a
ld a, TOTAL_GOLD
ld (gold_remaining), a
ld a, START_COL
ld (thief_col), a
ld a, START_ROW
ld (thief_row), a
call draw_room
call save_under
call draw_thief
call warden_enter ; this room's Warden, from the table
call save_warden
call draw_warden
ret
mark_step:
ld bc, KEYS_SPACE
in a, (c)
bit 0, a
ret nz
call cell_state_addr
ld (hl), '+'
ld hl, mark_tile
ld de, under_thief
ld bc, 8
ldir
ld a, MARK_ATTR
ld (under_thief + 8), a
ret
cell_state_addr:
call room_entry_addr
ld a, (hl)
inc hl
ld h, (hl)
ld l, a
push hl
ld a, (thief_row)
ld l, a
ld h, 0
add hl, hl
add hl, hl
add hl, hl
add hl, hl
add hl, hl
ld a, (thief_col)
ld e, a
ld d, 0
add hl, de
pop de
add hl, de
ret
room_entry_addr:
ld a, (current_room)
ld l, a
ld h, 0
ld d, h
ld e, l
add hl, hl
add hl, de
add hl, hl
ld de, rooms
add hl, de
ret
; ----------------------------------------------------------------------------
; find_torch — scan the current room's map for 'T', remember where it is (or
; NO_TORCH if the room is unlit).
; ----------------------------------------------------------------------------
; find_torches — collect every 'T' in the current room (up to MAX_TORCHES) into
; torch_list as (col, row) pairs; torch_count says how many.
find_torches:
xor a
ld (torch_count), a
call room_entry_addr
ld a, (hl)
inc hl
ld h, (hl)
ld l, a
ld b, 0
.fr_row:
ld c, 0
.fr_col:
ld a, (hl)
cp 'T'
jr nz, .fr_skip
ld a, (torch_count)
cp MAX_TORCHES
jr nc, .fr_skip
push hl
add a, a ; count * 2
ld e, a
ld d, 0
ld hl, torch_list
add hl, de
ld (hl), c ; column
inc hl
ld (hl), b ; row
pop hl
ld a, (torch_count)
inc a
ld (torch_count), a
.fr_skip:
inc hl
inc c
ld a, c
cp 32
jr nz, .fr_col
inc b
ld a, b
cp 24
jr nz, .fr_row
ret
; ----------------------------------------------------------------------------
; shade_for_cell — row in B, column in C. Returns a shade 0..4 in A: the
; Chebyshev distance to the torch, halved and clamped. Near the flame = 0
; (lightest); far away = 4 (darkest). No torch = darkest everywhere.
; ----------------------------------------------------------------------------
shade_for_cell:
push bc
ld a, b
ld (cell_row), a
ld a, c
ld (cell_col), a
ld a, (torch_count)
or a
jr z, .sf_dark
ld a, 255
ld (min_dist), a
ld hl, torch_list
ld a, (torch_count)
ld b, a ; loop count
.sf_loop:
ld a, (cell_col)
sub (hl) ; - torch col
jr nc, .sf_dc
neg
.sf_dc:
ld d, a ; |dc|
inc hl ; -> torch row
ld a, (cell_row)
sub (hl)
jr nc, .sf_dr
neg
.sf_dr:
inc hl ; -> next torch pair
cp d ; A = |dr|; take the larger
jr nc, .sf_mx
ld a, d
.sf_mx:
ld e, a ; this torch's distance
ld a, (min_dist)
cp e
jr c, .sf_keep ; min already smaller
ld a, e
ld (min_dist), a
.sf_keep:
djnz .sf_loop
ld a, (current_room)
ld c, a
ld b, 0
ld hl, room_falloff
add hl, bc
ld b, (hl)
ld a, (min_dist)
inc b
.sf_shift:
dec b
jr z, .sf_clamp
srl a
jr .sf_shift
.sf_clamp:
cp MAX_SHADE + 1
jr c, .sf_done
ld a, MAX_SHADE
.sf_done:
pop bc
ret
.sf_dark:
ld a, MAX_SHADE
pop bc
ret
draw_room:
call find_torches
call room_entry_addr
ld a, (hl)
inc hl
ld h, (hl)
ld l, a
ld (map_ptr), hl
ld b, 0
.room_row:
ld c, 0
.room_col:
ld hl, (map_ptr)
ld a, (hl)
cp '.'
jr nz, .not_floor
call shade_for_cell
add a, a
ld e, a
ld d, 0
ld hl, shade_tiles
add hl, de
ld e, (hl)
inc hl
ld d, (hl)
ld (tile_ptr), de
ld a, FLOOR_ATTR
ld (tile_attr), a
call draw_tile
jr .cell_done
.not_floor:
call lookup_tile
call draw_tile
.cell_done:
ld hl, (map_ptr)
inc hl
ld (map_ptr), hl
inc c
ld a, c
cp 32
jr nz, .room_col
inc b
ld a, b
cp 24
jr nz, .room_row
ret
lookup_tile:
ld hl, palette
.scan:
cp (hl)
jr z, .found
inc hl
inc hl
inc hl
inc hl
jr .scan
.found:
inc hl
ld e, (hl)
inc hl
ld d, (hl)
ld (tile_ptr), de
inc hl
ld a, (hl)
ld (tile_attr), a
ret
draw_tile:
push bc
call attr_addr_cr
ld a, (tile_attr)
ld (hl), a
call scr_addr_cr
ld de, (tile_ptr)
ld b, 8
.tile_row:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .tile_row
pop bc
ret
player_step:
ld a, (thief_col)
ld (tcol), a
ld a, (thief_row)
ld (trow), a
ld bc, KEYS_OP
in a, (c)
bit 1, a
jr z, .left
bit 0, a
jr z, .right
ld bc, KEYS_Q
in a, (c)
bit 0, a
jr z, .up
ld bc, KEYS_A
in a, (c)
bit 0, a
jr z, .down
ret
.left:
ld hl, tcol
dec (hl)
jr .move
.right:
ld hl, tcol
inc (hl)
jr .move
.up:
ld hl, trow
dec (hl)
jr .move
.down:
ld hl, trow
inc (hl)
.move:
ld a, (trow)
ld b, a
ld a, (tcol)
ld c, a
call wall_at
ret nz
call restore_under
ld a, (tcol)
ld (thief_col), a
ld a, (trow)
ld (thief_row), a
call collect_gold ; the new cell might be gold — lift it first
call save_under
call draw_thief
call sfx_step
call check_exit
ret
wall_at:
call attr_addr_cr
bit WALL_BIT, (hl)
ret
check_exit:
ld a, (thief_col)
or a
jr z, .west
cp 31
jr z, .east
ld a, (thief_row)
or a
jr z, .north
cp 23
jr z, .south
ret
.east:
call room_entry_addr
ld de, 4
add hl, de
ld a, (hl)
cp NO_EXIT
ret z
ld (current_room), a
ld a, 1
ld (thief_col), a
jr .enter
.west:
call room_entry_addr
ld de, 5
add hl, de
ld a, (hl)
cp NO_EXIT
ret z
ld (current_room), a
ld a, 30
ld (thief_col), a
jr .enter
.north:
call room_entry_addr
inc hl
inc hl
ld a, (hl)
cp NO_EXIT
ret z
ld (current_room), a
ld a, 22
ld (thief_row), a
jr .enter
.south:
call room_entry_addr
inc hl
inc hl
inc hl
ld a, (hl)
cp NO_EXIT
ret z
ld (current_room), a
ld a, 1
ld (thief_row), a
.enter:
call sfx_door
call draw_room
call save_under
call draw_thief
call warden_enter ; this room's Warden, clear of the entry cell
call save_warden
call draw_warden
ret
pos_bc:
ld a, (thief_row)
ld b, a
ld a, (thief_col)
ld c, a
ret
save_under:
call pos_bc
call scr_addr_cr
ld de, under_thief
ld b, 8
.save_row:
ld a, (hl)
ld (de), a
inc de
inc h
djnz .save_row
call pos_bc
call attr_addr_cr
ld a, (hl)
ld (under_thief + 8), a
ret
restore_under:
call pos_bc
call scr_addr_cr
ld de, under_thief
ld b, 8
.restore_row:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .restore_row
call pos_bc
call attr_addr_cr
ld a, (under_thief + 8)
ld (hl), a
ret
draw_thief:
call pos_bc
call attr_addr_cr
ld (hl), THIEF
call pos_bc
call scr_addr_cr
ld de, thief
ld b, 8
.thief_row:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .thief_row
ret
; ----------------------------------------------------------------------------
; The Warden — something shares the keep. A second mover, drawn exactly like the
; thief: a private under-buffer and its own save / draw, a spectral hooded
; sentinel. First we simply give it a body (it neither moves nor harms yet).
; ----------------------------------------------------------------------------
wpos_bc:
ld a, (warden_row)
ld b, a
ld a, (warden_col)
ld c, a
ret
save_warden:
call wpos_bc
call scr_addr_cr
ld de, under_warden
ld b, 8
.svw_row:
ld a, (hl)
ld (de), a
inc de
inc h
djnz .svw_row
call wpos_bc
call attr_addr_cr
ld a, (hl)
ld (under_warden + 8), a
ret
draw_warden:
call wpos_bc
call attr_addr_cr
ld (hl), WARDEN
call wpos_bc
call scr_addr_cr
ld de, warden_glyph
ld b, 8
.drw_row:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .drw_row
ret
; A spectral hooded sentinel: a cowl with dark eye-slits over a robe that frays
; at the hem. Cold, faceless, unmistakably a figure.
warden_glyph:
defb %00111100
defb %01111110
defb %01100110
defb %01111110
defb %00111100
defb %01111110
defb %01111110
defb %01011010
restore_warden:
call wpos_bc
call scr_addr_cr
ld de, under_warden
ld b, 8
.rsw_row:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .rsw_row
call wpos_bc
call attr_addr_cr
ld a, (under_warden + 8)
ld (hl), a
ret
; warden_step — the patrol. Walks its column one cell every WARDEN_SPEED frames,
; after a WARDEN_GATHER beat, reversing at walls. Deterministic: a route you learn
; and time. It reads the thief's cell as a wall (his attribute has WALL_BIT set),
; so it turns aside at him for now — the catch is Unit 11.
warden_step:
ld a, (warden_timer)
dec a
ld (warden_timer), a
ret nz
ld a, WARDEN_SPEED
ld (warden_timer), a
; propose the next cell along the patrol axis, in the current dir
ld a, (warden_axis)
or a
jr nz, .ws_vert
.ws_horiz:
ld a, (warden_row)
ld b, a ; B = row (fixed)
ld a, (warden_dir)
ld hl, warden_col
add a, (hl)
ld c, a ; C = next col
jr .ws_have
.ws_vert:
ld a, (warden_col)
ld c, a ; C = col (fixed)
ld a, (warden_dir)
ld hl, warden_row
add a, (hl)
ld b, a ; B = next row
.ws_have:
ld a, b ; the thief there? caught — check BEFORE
ld hl, thief_row ; wall_at, because his own cell reads as wall
cp (hl)
jr nz, .ws_wall
ld a, c
ld hl, thief_col
cp (hl)
jr nz, .ws_wall
ld a, 1
ld (caught), a
ret
.ws_wall:
push bc
call wall_at
pop bc
jr z, .ws_commit ; floor ahead — step onto it
ld a, (warden_dir) ; wall ahead — reverse, wait a beat
neg
ld (warden_dir), a
ret
.ws_commit:
push bc ; keep the proposed (row B, col C)
call restore_warden
pop bc
ld a, c
ld (warden_col), a
ld a, b
ld (warden_row), a
call save_warden ; photograph the new cell's ground
call draw_warden
ret
; ----------------------------------------------------------------------------
; warden_enter — instantiate the current room's Warden from warden_table: place
; it at the route-start (chosen clear of the entry cell), set its axis, and start
; its gather. Called on new_game and on every room change. A second mover is a
; table entry — like the torches and the gold.
; ----------------------------------------------------------------------------
warden_enter:
ld a, (current_room)
add a, a
add a, a ; * 4 bytes per table row
ld e, a
ld d, 0
ld hl, warden_table
add hl, de
ld a, (hl)
ld (warden_col), a
inc hl
ld a, (hl)
ld (warden_row), a
inc hl
ld a, (hl)
ld (warden_dir), a
inc hl
ld a, (hl)
ld (warden_axis), a
ld a, WARDEN_GATHER
ld (warden_timer), a
ret
; warden_table — one row per room: start col, start row, dir (+1/-1), axis.
; Each route crosses that room's gold and starts clear of the entry cell.
warden_table:
defb WARDEN_COL0, WARDEN_ROW0, -1, AXIS_VERT ; Hall — the gold's column
defb 24, 15, -1, AXIS_VERT ; Gallery — column 24, lower chamber
defb 15, 20, -1, AXIS_HORIZ ; Vault — row 20, between the coins
; ----------------------------------------------------------------------------
; The gold — the keep's goal. Step onto a coin and it lifts: the map cell turns
; to floor (gone for good), the cell repaints as plain floor (no lighting yet),
; a chime sounds, and the counter ticks down.
; ----------------------------------------------------------------------------
collect_gold:
call cell_state_addr ; HL -> map cell at the thief's position
ld a, (hl)
cp 'G'
ret nz
ld (hl), '.' ; the gold is taken — floor from now on
call pos_bc ; B = row, C = col
call draw_floor_cell ; repaint the cell as plain floor
call sfx_pickup
ld hl, gold_remaining
dec (hl)
ld a, (hl)
or a
call z, win ; the last coin — the keep stands
ret
; draw_floor_cell — paint the floor tile at (row B, col C). Lighting (Unit 13)
; will replace this with a shade chosen by distance from the nearest torch.
draw_floor_cell:
call shade_for_cell
add a, a
ld e, a
ld d, 0
ld hl, shade_tiles
add hl, de
ld e, (hl)
inc hl
ld d, (hl)
ld (tile_ptr), de
ld a, FLOOR_ATTR
ld (tile_attr), a
call draw_tile
ret
; ----------------------------------------------------------------------------
; beep — the one tone primitive (the tiny game's blip, reused). B = cycles,
; C = the delay between speaker toggles (the pitch; larger C = lower).
; ----------------------------------------------------------------------------
beep:
.bp_cycle:
ld a, %00010000
out ($FE), a
ld e, c
.bp_hi:
dec e
jr nz, .bp_hi
xor a
out ($FE), a
ld e, c
.bp_lo:
dec e
jr nz, .bp_lo
djnz .bp_cycle
ret
; sfx_pickup — a bright two-blip chime: the sound of gold.
sfx_pickup:
ld b, 8
ld c, 20
call beep
ld b, 8
ld c, 14
call beep
ret
; sfx_step — a footfall: short and low, gone almost before you notice it. Played
; under every successful move.
sfx_step:
ld b, 5
ld c, 90
call beep
ret
; sfx_door — a creak: a tone that falls in pitch as it plays, so the note groans
; downward — a heavy door swinging on its hinges.
sfx_door:
ld c, 36 ; start higher
.sd_sweep:
ld b, 3
push bc
call beep
pop bc
inc c ; lower the pitch a little
inc c
ld a, c
cp 130 ; until it has groaned down low
jr c, .sd_sweep
ret
gold_tile:
defb %00000000
defb %00111100
defb %01111110
defb %01111110
defb %01111110
defb %01111110
defb %00111100
defb %00000000
; One byte of mood per room: how slowly its light fades.
room_falloff:
defb 2 ; Hall — broad, soft pool
defb 1 ; Gallery — medium
defb 0 ; Vault — tight pool, deep dark
; The shade ramp: lightest (lit) to darkest (deep shadow), all blue/black dither.
shade_tiles:
defw shade0_tile
defw shade1_tile
defw shade2_tile
defw shade3_tile
defw shade4_tile
shade0_tile: ; lit — nearly all blue
defb %00000000
defb %00100010
defb %00000000
defb %00000000
defb %00000000
defb %10001000
defb %00000000
defb %00000000
shade1_tile:
defb %00100010
defb %00000000
defb %10001000
defb %00000000
defb %00100010
defb %00000000
defb %10001000
defb %00000000
shade2_tile: ; the half-and-half slate from Unit 2
defb %10101010
defb %01010101
defb %10101010
defb %01010101
defb %10101010
defb %01010101
defb %10101010
defb %01010101
shade3_tile:
defb %10101010
defb %11111111
defb %01010101
defb %11111111
defb %10101010
defb %11111111
defb %01010101
defb %11111111
shade4_tile: ; deep shadow — nearly all black
defb %11111111
defb %11101110
defb %11111111
defb %10111011
defb %11111111
defb %11101110
defb %11111111
defb %10111011
torch_tile: ; a flame in its sconce
defb %00010000
defb %00111000
defb %00111000
defb %01111100
defb %01111100
defb %01111100
defb %00111000
defb %00010000
statue_tile:
defb %00111100
defb %01111110
defb %00111100
defb %00011000
defb %00011000
defb %00111100
defb %01111110
defb %01111110
banner_tile:
defb %01111110
defb %01111110
defb %01011010
defb %01011010
defb %01111110
defb %01111110
defb %00111100
defb %00011000
rubble_tile:
defb %00000000
defb %01100000
defb %01100000
defb %00000110
defb %00000110
defb %00011000
defb %00011000
defb %00000000
; ----------------------------------------------------------------------------
; show_title — black screen, the keep's name and a prompt; wait for SPACE (and
; release). Silent for now — the composed theme arrives in Unit 18. Words use the
; ROM's own 8x8 font at $3D00.
; ----------------------------------------------------------------------------
show_title:
di
call clear_screen
ld hl, str_title
ld b, 8
ld c, 11
call print_string
ld hl, str_prompt
ld b, 16
ld c, 6
call print_string
.tt_wait:
ld bc, KEYS_SPACE
in a, (c)
bit 0, a
jr nz, .tt_wait
.tt_rel:
ld bc, KEYS_SPACE
in a, (c)
bit 0, a
jr z, .tt_rel
ret
; show_win — the keep is cleared. Black screen, the words, the flourish, then
; wait for SPACE (and release) to return to the title.
show_win:
di
call clear_screen
ld hl, str_won
ld b, 9
ld c, 8
call print_string
ld hl, str_again
ld b, 15
ld c, 5
call print_string
call sfx_win
.sw_wait:
ld bc, KEYS_SPACE
in a, (c)
bit 0, a
jr nz, .sw_wait
.sw_rel:
ld bc, KEYS_SPACE
in a, (c)
bit 0, a
jr z, .sw_rel
ret
; win — the last coin is gone. Flourish, and raise the flag the loop watches.
win:
ld a, 1
ld (won), a
call sfx_win
ret
; sfx_win — an ascending flourish: a low note climbing in steps to a high one.
sfx_win:
ld c, 60
.swf_loop:
ld b, 12
push bc
call beep
pop bc
ld a, c
sub 8
ld c, a
cp 16
jr nc, .swf_loop
ret
; clear_screen — fill bitmap and attributes with zero: a black screen.
clear_screen:
ld hl, $4000
ld (hl), 0
ld de, $4001
ld bc, 6911
ldir
ret
; print_string — HL -> zero-terminated text, B = row, C = col.
print_string:
.ps_loop:
ld a, (hl)
or a
ret z
push hl
call print_char
pop hl
inc hl
inc c
jr .ps_loop
; print_char — A = character (32..127), B = row, C = col. Copies the ROM font
; glyph at $3D00 + (char-32)*8 to the screen, bright white.
print_char:
push bc
sub 32
ld l, a
ld h, 0
add hl, hl
add hl, hl
add hl, hl
ld de, $3D00
add hl, de
push hl
call scr_addr_cr
pop de
ld b, 8
.pc_row:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .pc_row
pop bc
call attr_addr_cr
ld (hl), %01000111
ret
str_title:
defb "SHADOWKEEP", 0
str_prompt:
defb "PRESS SPACE TO ENTER", 0
str_won:
defb "THE KEEP STANDS", 0
str_again:
defb "PRESS SPACE TO RETURN", 0
; ----------------------------------------------------------------------------
; show_lose — the mirror of show_win. Black screen, the words, the freezing
; sting, then wait for SPACE (and release) to return to the title.
; ----------------------------------------------------------------------------
show_lose:
di
call clear_screen
ld hl, str_lost
ld b, 9
ld c, 8
call print_string
ld hl, str_again
ld b, 15
ld c, 5
call print_string
call sfx_caught
.slo_wait:
ld bc, KEYS_SPACE
in a, (c)
bit 0, a
jr nz, .slo_wait
.slo_rel:
ld bc, KEYS_SPACE
in a, (c)
bit 0, a
jr z, .slo_rel
ret
; sfx_caught — the plunge into stasis: a quick fall, then a deep, long toll as
; the stone closes over you. The opposite of the win flourish.
sfx_caught:
ld c, 16
.sca_fall:
ld b, 5
push bc
call beep
pop bc
ld a, c
add a, 7
ld c, a
cp 100
jr c, .sca_fall
ld b, 60
ld c, 130
call beep
ret
str_lost:
defb "THE KEEP SLEEPS", 0
scr_addr_cr:
ld a, b
and %00011000
or %01000000
ld h, a
ld a, b
and %00000111
rrca
rrca
rrca
or c
ld l, a
ret
attr_addr_cr:
ld a, b
ld l, a
ld h, 0
add hl, hl
add hl, hl
add hl, hl
add hl, hl
add hl, hl
ld de, $5800
add hl, de
ld a, c
ld e, a
ld d, 0
add hl, de
ret
palette:
defb '.'
defw floor_tile
defb FLOOR_ATTR
defb '#'
defw wall_tile
defb WALL_ATTR
defb '+'
defw mark_tile
defb MARK_ATTR
defb 'G'
defw gold_tile
defb GOLD_ATTR
defb 'T'
defw torch_tile
defb TORCH_ATTR
defb 'S'
defw statue_tile
defb STATUE_ATTR
defb 'B'
defw banner_tile
defb BANNER_ATTR
defb 'o'
defw rubble_tile
defb RUBBLE_ATTR
; ----------------------------------------------------------------------------
; The keep: three rooms. Hall -east-> Gallery -north-> Vault, and back.
; entry: map ptr, North, South, East, West
; ----------------------------------------------------------------------------
rooms:
defw room0_state
defb NO_EXIT, NO_EXIT, 1, NO_EXIT ; Hall: east -> Gallery
defw room1_state
defb 2, NO_EXIT, NO_EXIT, 0 ; Gallery: north -> Vault, west -> Hall
defw room2_state
defb NO_EXIT, 1, NO_EXIT, NO_EXIT ; Vault: south -> Gallery
; The Great Hall — four pillars, east door at row 11.
room0_template:
defb "###############T################"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "B..............S...............B"
defb "#.............ooo.........G....#"
defb "#..............................#"
defb "T........##..........##........T"
defb "#........##..........##........#"
defb "#..............................#"
defb "#..............................."
defb "#..............................#"
defb "#..............................#"
defb "#........##..........##........#"
defb "#........##..........##........#"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#.........................G....#"
defb "#..............................#"
defb "#..............................#"
defb "################################"
; The Gallery — a dividing wall with one gap (column 15). West door (row 11)
; back to the Hall; north door (column 15) up to the Vault.
room1_template:
defb "###############.################"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#..............................T"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "###############.################"
defb "#..............................#"
defb "#..............................#"
defb "........................G......#"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "B..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#........................ooo...#"
defb "#..............................#"
defb "#.......................G......#"
defb "#..............................#"
defb "#..............................#"
defb "###############T################"
; The Vault — a great altar of stone in the middle, south door (column 15)
; down to the Gallery.
room2_template:
defb "################################"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#.............#T##.............#"
defb "#.............####.............#"
defb "#.............####.............#"
defb "#.............####.............#"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#..............................#"
defb "#.........G.........G..........#"
defb "#..............................#"
defb "#..............................#"
defb "###############.################"
floor_tile:
defb %10101010
defb %01010101
defb %10101010
defb %01010101
defb %10101010
defb %01010101
defb %10101010
defb %01010101
wall_tile:
defb %00010001
defb %00000000
defb %01000100
defb %00000000
defb %00010001
defb %00000000
defb %01000100
defb %00000000
mark_tile:
defb %00000000
defb %00011000
defb %00011000
defb %01111110
defb %01111110
defb %00011000
defb %00011000
defb %00000000
thief:
defb %00011000
defb %00111100
defb %01111110
defb %01111110
defb %01111110
defb %01111110
defb %00111100
defb %00100100
current_room:
defb 0
thief_col:
defb START_COL
thief_row:
defb START_ROW
tcol:
defb 0
trow:
defb 0
map_ptr:
defw 0
tile_ptr:
defw 0
tile_attr:
defb 0
under_thief:
defb 0, 0, 0, 0, 0, 0, 0, 0, 0
gold_remaining:
defb TOTAL_GOLD
won:
defb 0
under_warden:
defb 0, 0, 0, 0, 0, 0, 0, 0, 0
warden_col:
defb WARDEN_COL0
warden_row:
defb WARDEN_ROW0
warden_dir:
defb -1
warden_axis:
defb AXIS_VERT
warden_timer:
defb WARDEN_GATHER
caught:
defb 0
torch_count:
defb 0
cell_row:
defb 0
cell_col:
defb 0
min_dist:
defb 0
torch_list:
defs MAX_TORCHES * 2
room0_state:
defs 768
room1_state:
defs 768
room2_state:
defs 768
end start
Walk a dozen steps across the Hall and a soft low click falls under each one — the weight of stone underfoot:
Cross from one chamber to the next and the door answers — a single pitch swept downward, groaning on its hinges:
Small sounds — but the keep stops being a silent diorama between its chimes and starts being a place with weight.
Try this: a heavier tread
Raise sfx_step’s B to 12 and its C to 120. The step gets longer and lower — a booted guard, not a barefoot thief. Sound characterises who is walking as surely as the sprite does. Drop B to 2 and the footfall becomes a light tick; you can hear a different body just by changing two numbers.
Try this: reverse the creak
Swap sfx_door to sweep the other way — start C high and dec it down to a small value. Now the door rises as it opens instead of falling. One groans shut, the other whines open; pick the one that sounds like the keep you’re building. (Mind the loop test — sweeping down means jr nc / a different comparison.)
Try this: give the Warden a sound
The Warden patrols in silence. Give it a voice — a slow, low pulse each time it steps, so you can hear it coming without seeing it. A footstep for the thing that hunts you changes the whole feel of the dark: now the crypt has a heartbeat. (Call your new sound from warden_step’s commit path, and keep it quieter and lower than the thief’s, so the two tread differently.)
When it’s wrong, see why
- No sound at all.
beepisn’t being reached, or the calls aren’t wired — checksfx_stepfollowsdraw_thiefandsfx_doorsits at the top of.enter. - The footstep is a long buzz.
Bis far too high — a footfall is a handful of cycles, not a held note. Keep it short. - The door clicks instead of creaks. The sweep loop runs once — check
Cstarts small and thecplimit is high enough to sweep across a real range. - Every step stutters the movement. The sound is long enough to be felt as a pause. Shorten
sfx_step; ambient sound should sit under the action, not interrupt it. - The creak plays twice at a door.
sfx_dooris called on both the exit test and the enter — call it once, on entry.
Before and after
You started with a keep that sounded only when something happened and finished with one that sounds as you move through it — a click of stone under each step, a groan of hinges at each door. The tool was the beeper already ringing your chimes and tolls; the new work was two small routines and two hooks. Nothing on screen changed, and yet the keep feels twice as real, because half of believing a place is hearing it. Sound as atmosphere, not feedback — the difference between a game that pings and a place that breathes.
What you’ve learnt
- Ambient sound is different from event sound. A footfall and a creak are about the place; a chime and a toll are about what happened. A believable keep needs both.
- One primitive, many voices. The same
beeprings a chime, tolls a capture, clicks a footstep and groans a door — the composition is all in B and C. - A sweep is a gesture. Falling pitch reads as weight and closing; rising reads as opening. A moving tone carries meaning a single note can’t.
- Ambience sits under the action. Keep it short and quiet; it should colour the moment, never interrupt it.
What’s next
The keep is heard as you move — but its title screen still waits in silence. A game announces itself. In Unit 18, “A Theme in One Voice,” we turn the beeper from effects back to music: a short, solemn phrase in D minor that loops on the title while the keep waits for you, the melody carrying the whole mood on one voice. The same bit that clicks your footsteps will, on the title, sing.