105 lines
1.4 KiB
NASM
105 lines
1.4 KiB
NASM
.p816
|
|
.smart
|
|
|
|
.include "macros.inc"
|
|
.include "registers.inc"
|
|
|
|
.include "header.asm"
|
|
|
|
.segment "CODE"
|
|
|
|
VRAM_CHARS = $0000
|
|
VRAM_BG1 = $1000
|
|
|
|
start:
|
|
.include "init.asm"
|
|
|
|
; Set up the color palette
|
|
stz CGADD
|
|
|
|
; Color 0 - black
|
|
lda #$00
|
|
sta CGDATA
|
|
lda #$00
|
|
sta CGDATA
|
|
|
|
; Color 1 - red
|
|
lda #$1f
|
|
sta CGDATA
|
|
lda #$00
|
|
sta CGDATA
|
|
|
|
; Color 2 - green
|
|
lda #$e0
|
|
sta CGDATA
|
|
lda #$03
|
|
sta CGDATA
|
|
|
|
; Color 3 - blue
|
|
lda #$00
|
|
sta CGDATA
|
|
lda #$7c
|
|
sta CGDATA
|
|
|
|
; Graphics mode 0, 8x8 tiles
|
|
stz BGMODE
|
|
|
|
; Set BG1 and tile map and character data
|
|
lda #>VRAM_BG1
|
|
sta BG1SC
|
|
lda #VRAM_CHARS
|
|
sta BG12NBA
|
|
|
|
; Load character data into VRAM
|
|
lda #$80
|
|
sta VMAIN
|
|
ldx #VRAM_CHARS
|
|
stx VMADDL
|
|
@charset_loop:
|
|
lda charset,x
|
|
sta VMDATAL
|
|
inx
|
|
lda charset,x
|
|
sta VMDATAH
|
|
inx
|
|
cpx #(charset_end - charset)
|
|
bne @charset_loop
|
|
|
|
; Manually clear screen
|
|
ldx #(VRAM_BG1)
|
|
@loop:
|
|
stx VMADDL
|
|
lda #$00
|
|
sta VMDATAL
|
|
stz VMDATAH
|
|
inx
|
|
cpx #(VRAM_BG1 + 32 * 29)
|
|
bne @loop
|
|
|
|
; write tile to position (1, 1)
|
|
TILE_X = 1
|
|
TILE_Y = 1
|
|
ldx #(VRAM_BG1 + (TILE_Y * 32) + TILE_X)
|
|
stx VMADDL
|
|
lda #$01 ; tile number
|
|
sta VMDATAL
|
|
stz VMDATAH
|
|
|
|
; Show bg1
|
|
lda #%00000001
|
|
sta TM
|
|
|
|
|
|
lda #$0f
|
|
sta INIDISP
|
|
|
|
busywait:
|
|
bra busywait
|
|
|
|
nmi:
|
|
bit RDNMI
|
|
_rti:
|
|
rti
|
|
|
|
.include "charset.asm"
|