1,885
edits
Changes
→Type on the Screen
iny
jmp next
== Place a Graphic on the Screen ==
define WIDTH 4 ; width of graphic
define HEIGHT 4 ; height of graphic
lda #$25 ; create a pointer at $10
sta $10 ; which points to where
lda #$02 ; the graphic should be drawn
sta $11
lda #$00 ; number of rows we've drawn
sta $12 ; is stored in $12
ldx #$00 ; index for data
ldy #$00 ; index for screen column
draw: lda data,x
sta ($10),y
inx
iny
cpy #WIDTH
bne draw
inc $12 ; increment row counter
lda #HEIGHT ; are we done yet?
cmp $12
beq done ; ...exit if we are
lda $10 ; load pointer
clc
adc #$20 ; add 32 to drop one row
sta $10
lda $11 ; carry to high byte if needed
adc #$00
sta $11
ldy #$00
beq draw
done: brk ; stop when finished
data:
dcb 00,03,03,00
dcb 07,00,00,07
dcb 07,00,00,07
dcb 00,03,03,00
