MOre notes and experimentation

tic_tac.asm

@@ -87,7 +87,7 @@ sta $420b ;start DMA
 lda #%10000000 ; VRAM writing mode
 sta $2115
 
-ldx #$4000
+ldx #$5000
 stx $2116 ; write to VRAM
 
 ;ugly code starts here - it writes the # shape I mentioned before.
@@ -144,11 +144,15 @@ stx $2118 ;data for VRAM write register
 lda #%00110000 ; 16x16 tiles, mode 0
 sta $2105     ; $2105 is the mode for bg mode + tile size
 
-lda #%01000000 ; data starts from $4000
-sta $2107      ; for bg1
+lda #$50 ; data starts from $4000
+sta $2107      ; for bg1     ; $2107 is address of tile map location for BG1
+; tile map location registers:
+; %aaaaaass
+; a's <- tile map address location, << 11
+; ss <-  32x32, 32x64, 32x64, 64x64
 
-lda #%0110000 ; and $6000
-sta $2108 ; for bg2
+lda #60 ; and $6000
+sta $2108 ; for bg2   ; and $2108 is tile map location for BG2
 
 stz $210b	    ; BG1 and BG2 use the $0000 tiles
 
@@ -176,19 +180,24 @@ sta $2100
 lda #%10000001  ; enable NMI and joypads
 sta $4200
 
-    Spin_Loop
-
-lda #%00000011
+lda #%00011111
 sta $2100
 
 mainloop:
     Spin_Loop
-    lda #%00000011
-    sta $2100
+    ;lda #%00000011
+    ;sta $2100
+
+    lda #%00110000
+    sta $2105
 
     Spin_Loop
-    lda #$0f
-    sta $2100
+
+    ;lda #$0f
+    ;sta $2100
+
+    lda #%00000000
+    sta $2105
 
     jmp mainloop