mirror of
https://github.com/deater/tb1.git
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285 lines
5.9 KiB
ArmAsm
285 lines
5.9 KiB
ArmAsm
.segment "STARTUP"
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display_opening:
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rep #$10 ; X/Y = 16 bit
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.i16
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sep #$20 ; mem/A = 8 bit
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.a8
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;==========================
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; Setup Backgrounds
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;==========================
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; we want the BG1 Tilemap to start at VRAM $F000 (60k)
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; Format is
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; aaaa aass a is shifted by 10 for address
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; ss = size of screen in tiles 00 = 32x32
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;
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; 1111 0000
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lda #$f0 ; BG1 Tilemap starts at VRAM $F000
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sta $2107 ; bg1 src
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; we want the BG2 Tilemap to start at VRAM $F800
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; Format is
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; aaaa aass a is shifted by 10 for address
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; ss = size of screen in tiles 00 = 32x32
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;
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; 1111 0000
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; lda #$f8 ; BG2 Tilemap starts at VRAM $F800
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; sta $2108 ; bg1 src
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; aaaa bbbb a= BG2 tiles, b= BG1 tiles
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; bbbb<<13
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; 0000 0000
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; our BG1 tiles are stored starting in VRAM $0000
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; our BG2 tiles are stored starting in VRAM $e000
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; lda #$e0
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lda #$00
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sta $210b ; bg1 tile data starts at VRAM 0000
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;==============
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; Load Palettes
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;==============
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.a8
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.i16
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stz $2121 ; CGRAM color-generator read/write address
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ldy #$0200 ; we have 256 colors / 512 bytes
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ldx #$0000 ; pointer
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opening_copypal:
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lda f:vmw_logo_palette, x ; load byte of palette
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sta $2122 ; store to color generator
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inx
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dey
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bne opening_copypal
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;=====================
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; Load Tile Data
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;=====================
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; replace with DMA!
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rep #$20 ; set accumulator/mem to 16bit
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.a16
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.i16
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lda #$0020 ;
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sta $2116 ; set adddress for VRAM read/write
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; multiply by 2, so 0x0000
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ldy #$2580 ; Copy 300 tiles, which are 64 bytes each
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; 8x8 tile with 8bpp (four bits per pixel)
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; in 2-byte chunks, so
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; (300*64)/2 = 9600 = 0x2580
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ldx #$0000
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opening_copy_tile_data:
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lda f:vmw_logo_tile_data, x
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sta $2118 ; write the data
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inx ; increment by 2 (16-bits)
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inx
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dey ; decrement counter
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bne opening_copy_tile_data
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;=====================
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; Load TB_FONT Data
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;=====================
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; replace with DMA!
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; rep #$20 ; set accumulator/mem to 16bit
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;.a16
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;.i16
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; lda #$7000 ;
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; sta $2116 ; set adddress for VRAM read/write
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; ; multiply by 2, so 0xe000
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;
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; ldy #$0800 ; Copy 128 tiles, which are 32 bytes each
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; ; 8x8 tile with 4bpp (four bits per pixel)
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;;; ; in 2-byte chunks, so
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; ; (128*32)/2 = 2048 = 0x0800
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;
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; ldx #$0000
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opening_copy_font_data:
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; lda f:tb_font, x
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; sta $2118 ; write the data
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; inx ; increment by 2 (16-bits)
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; inx
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; dey ; decrement counter
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; bne opening_copy_font_data
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;===================================
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; clear background to linear tilemap
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;===================================
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.a16
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.i16
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opening_clear_linear_tilemap:
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; 6 down, 1 right = (6*32)+1 = 97 = 0xc1
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lda #$f0c1 ; we set tilemap to be at VRAM 0xf000 earlier
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sta $2116
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ldy #$0001 ; clear counters
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; store to VRAM
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; the bottom 8 bits is the tile to use
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; the top 8 bits is vhopppcc
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; vert flip, horiz flip o=priority
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; p = palette, c=top bits of tile#
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ldx #$0001
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; 8-bit color so ppp is 0
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; and we have a linear tilemap
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; 0000 0000
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; vhop ppcc cccc cccc
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.a16
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.i16
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opening_fill_screen_loop:
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cpx #31
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bne opening_not_thirty
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stz $2118
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stz $2118
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ldx #$0000
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bra opening_check_end
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opening_not_thirty:
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tya
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sta $2118
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iny
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opening_check_end:
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inx
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cpy #$0140 ; (10*32) = 0x140
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bne opening_fill_screen_loop
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; Write String to Background
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;opening_put_string:
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; lda #$fd08 ; set VRAM address
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; f800 = upper left
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; want 4x20, so (20 * 64) + 4*2 = 1288 = 0x508
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; fd08
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; sta $2116 ; set VRAM r/w address
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; ldy #$000d ; length of string
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; ldx #$0000 ; string index
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; lda #$0200 ; clear A
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opening_copy_string:
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; sep #$20 ; set accumulator to 8 bit
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; as we only want to do an 8-bit load
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.a8
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; lda opening_string, x ; load string character
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; while leaving top 8-bits alone
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; beq opening_done_copy_string
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; sec
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; sbc #$20
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; rep #$20 ; set accumulator back to 16 bit
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.a16
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; sta $2118 ; store to VRAM
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; the bottom 8 bits is the tile to use
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; the top 8 bits is vhopppcc
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; vert flip, horiz flip o=priority
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; p = palette, c=top bits of tile#
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; inx ; increment string pointer
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; bra opening_copy_string
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opening_done_copy_string:
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opening_setup_video:
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sep #$20 ; set accumulator to 8 bit
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; as we only want to do an 8-bit load
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.a8
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.i16
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; Enable sprite
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; sssnnbbb
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; ss = size (8x8 in our case)
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; nn = name
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; bb = base selection, VRAM >> 14
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; lda #%00000010 ; point at 0x4000 in VRAM
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; sta $2101
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; 000abcde
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; a = object, b=BG4 c=BG3 d=BG2 e=BG1
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; lda #%00010001 ; Enable BG1
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; lda #%00000011 ; Enable BG1
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lda #%00000001 ; Enable BG1
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sta $212c
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; disable subscreen
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stz $212d
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; abcd efff
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; abcd = 8 (0) or 16 width for BG1234
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; e = priority for BG3
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; fff = background mode
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lda #$03
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sta $2105 ; set Mode 3
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; a000 bbbb
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; a = screen on/off (0=on), ffff = brightness
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lda #$0f
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sta $2100 ; Turn on screen, full Brightness
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; lda #$81 ; Enable NMI (VBlank Interrupt) and joypads
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; sta $4200 ;
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less:
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; repeat forever
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; stp?
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bra less
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opening_string:
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.asciiz "A VMW SOFTWARE PRODUCTION"
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.segment "HIGHROM"
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tb_font:
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;.include "tbfont.inc"
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.include "tb1_opening.tiles"
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