Part 2

homebrew-tutorial/charset.asm

@@ -0,0 +1,38 @@
+charset:
+    ; tile 0x00
+        .byte   %00000000
+        .byte   %00000000
+        .byte   %00000000
+        .byte   %00000000
+        .byte   %00000000
+        .byte   %00000000
+        .byte   %00000000
+        .byte   %00000000
+        .byte   %00000000
+        .byte   %00000000
+        .byte   %00000000
+        .byte   %00000000
+        .byte   %00000000
+        .byte   %00000000
+        .byte   %00000000
+        .byte   %00000000
+
+    ; tile 0x01
+        .byte   %11111111 ; row 0, color 0
+        .byte   %00000000 ; row 0, color 1
+        .byte   %10000001 ; row 1, color 0
+        .byte   %00000000 ; row 1, color 1
+        .byte   %10000001 ; row 2, color 0
+        .byte   %00000000 ; row 2, color 1
+        .byte   %10000001 ; row 3, color 0
+        .byte   %00001000 ; row 3, color 1
+        .byte   %10011001 ; row 4, color 0
+        .byte   %00001000 ; row 4, color 1
+        .byte   %10000001 ; row 5, color 0
+        .byte   %00000000 ; row 5, color 1
+        .byte   %10000001 ; row 6, color 0
+        .byte   %00000000 ; row 6, color 1
+        .byte   %11111111 ; row 7, color 0
+        .byte   %00000000 ; row 7, color 1
+
+charset_end:

homebrew-tutorial/main.asm

@@ -8,19 +8,79 @@
 
 .segment "CODE"
 
+VRAM_CHARS = $0000
+VRAM_BG1 = $1000
+
 start:
     .include "init.asm"
 
     ; Set up the color palette
     stz CGADD
-    ; Set color zero to some color
+
-    ; $001f = %0000000000011111
+    ; Color 0 - black
-    ;           bbbbbgggggrrrrr
+    lda #$00
-    lda #$ff
+    sta CGDATA
+    lda #$00
+    sta CGDATA
+
+    ; Color 1 - red
+    lda #$1f
+    sta CGDATA
+    lda #$00
+    sta CGDATA
+
+    ; Color 2 - blue
+    lda #$e0
     sta CGDATA
     lda #$03
     sta CGDATA
 
+    ; Color 3 - green
+    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
+
+    ; 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
 
@@ -31,3 +91,5 @@ nmi:
     bit RDNMI
 _rti:
     rti
+
+.include "charset.asm"