http://www.jwz.org/xscreensaver/xscreensaver-5.08.tar.gz

[xscreensaver] / hacks / images / m6502 / starfield2d.asm

diff --git a/hacks/images/m6502/starfield2d.asm b/hacks/images/m6502/starfield2d.asm
new file mode 100644 (file)
index 0000000..4c26efe
--- /dev/null
+++ b/hacks/images/m6502/starfield2d.asm
@@ -0,0 +1,50 @@
+; 2d starfield
+; Submitted by Anonymous
+
+i:ldx #$7
+g:lda $fe
+  and #3
+  adc #1
+  sta $0,x
+  lda $fe
+  and #$1f
+  sta $20,x
+  dex
+  bpl g
+f:
+  lda #$ff
+  sta $10
+  delay:
+  nop
+  dec $10
+  bne delay
+
+  lda #$00
+  sta $80
+  lda #$02
+  sta $81
+  ldx #$7
+l:lda $20,x
+  pha
+  clc
+  sbc $00,x
+  and #$1f
+  sta $20,x
+  lda $20,x
+  tay
+  lda #1
+  sta ($80),y
+  pla
+  tay
+  lda #0
+  sta ($80),y
+  lda $80
+  clc
+  adc #$80
+  bne n
+  inc $81
+n:sta $80
+  dex
+  bpl l
+  jmp f
+