From af67f17da1e817fa1e26d4eaa72c5764b4bacaa9 Mon Sep 17 00:00:00 2001
From: Paul Gardner-Stephen <paul@servalproject.org>
Date: Wed, 24 Apr 2019 14:57:15 +0930
Subject: [PATCH] reduce avoidable byte similarities with C64 KERNAL

---
 c64/kernal/getin.s  | 2 +-
 c64/kernal/ramtas.s | 8 +++++++-
 c64/kernal/stop.s   | 2 +-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/c64/kernal/getin.s b/c64/kernal/getin.s
index f7a0aa16..6df398c1 100644
--- a/c64/kernal/getin.s
+++ b/c64/kernal/getin.s
@@ -6,8 +6,8 @@ getin:
 	bne +
 
 	;; Nothing in keyboard buffer to read
-	lda #$00
 	sec
+	lda #$00
 	rts
 	
 *
diff --git a/c64/kernal/ramtas.s b/c64/kernal/ramtas.s
index ec240259..274f97c5 100644
--- a/c64/kernal/ramtas.s
+++ b/c64/kernal/ramtas.s
@@ -10,8 +10,14 @@ ramtas_l1:
 	INY
 	BNE ramtas_l1
 ramtas_l2:
-	STA $0200,Y
+	;; How many ways are there to efficiently erase these two pages
+	;; of RAM? We would like to avoid any unnecessary byte similarity
+	;; with the C64 KERNAL. Thus we do $0300 before $0200, even though
+	;; with the longer sequence of identicale bytes we see no basis for
+	;; it being copyrightable.  Again, we just want to redue the attack
+	;; surface for any misguided suit.
 	STA $0300,Y
+	STA $0200,Y
 	INY
 	BNE ramtas_l2
 
diff --git a/c64/kernal/stop.s b/c64/kernal/stop.s
index 88aa89ef..2f8e82e2 100644
--- a/c64/kernal/stop.s
+++ b/c64/kernal/stop.s
@@ -15,6 +15,6 @@ stop:
 	rts
 
 stop_pressed:
-	lda #$00
 	sec
+	lda #$00
 	rts