From 8274d0252b851209921c8d0e11005b3989b287f5 Mon Sep 17 00:00:00 2001
From: Oliver Schmidt <ol.sc@web.de>
Date: Sat, 11 Jan 2020 14:55:13 +0100
Subject: [PATCH] Initialize backLayer.

The zeropage variable backLayer was uninitialized. The program only happened to work if $0090 happened to be $00 (or $01 ?) on startup.
---
 src/apple2/penetrator.asm | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/apple2/penetrator.asm b/src/apple2/penetrator.asm
index 9a67c63..34bfe65 100644
--- a/src/apple2/penetrator.asm
+++ b/src/apple2/penetrator.asm
@@ -72,6 +72,8 @@ store:
     dex 
     bpl :-
 
+    sta backLayer                               ; set back layer to 0
+
     ldx #((BitMasksEnd - BitMasks) - 1)
 :
     lda BitMasks, x