Effetto simpatico trovato in un mini intro di Crossbow/Crest. Una scacchiera zoomante in modo testo e in meno di 128 bytes
; 128 byte checkerboard zoomer
; ripped from "2 BLOCKS TRACKMO" by Xbow/Crest
; isolated, disasmed and reduced by iAN CooG/HokutoForce
*=$0801
word eop
word 0
byte $9e,[start]d," (C) XBOW/CREST"
eop byte 0
start
loop1 LDX #$00
patch INX
CPX #$F8
BEQ next1
CPX #$28
BNE nopat
next1 LDA patch
EOR #$22 ; INX=$E8 DEX=$CA
STA patch
nopat STX loop1+1
LDA #$20
STA $3F
LDA #$04
STA $3C
STX $3D
STX $3E
LDA #$00
next2 STA $3B
LDY #$27
LDA $3F
loop2 STA ($3B),Y
DEX
BPL noeor
LDX $3E
EOR #$80 ; reverse/normal space
noeor DEY
BPL loop2
LDX $3E
DEC $3D
BPL noeor2
LDA $3F
EOR #$80 ; reverse/normal space
STA $3F
STX $3D
noeor2 LDA $3B
CLC
ADC #$28
BCC noinchi
INC $3C
noinchi CMP #$E8
BNE next2
LDA #$FF
w8rast
CMP $D012
BNE w8rast
BEQ loop1