From 8f10724a7f9805a93358e075f15a2cd6347db39c Mon Sep 17 00:00:00 2001
From: James Tauber <jtauber@jtauber.com>
Date: Sat, 6 Aug 2011 23:53:47 -0400
Subject: [PATCH] fixed inverse use of carry in SBC

---
 applepy.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/applepy.py b/applepy.py
index 6b5a652..5b72edb 100644
--- a/applepy.py
+++ b/applepy.py
@@ -620,10 +620,10 @@ class CPU:
             m1 = (m1 & 0x7F) - 0x80
         
         # twos complement subtraction
-        result1 = a1 - m1 - self.carry_flag
+        result1 = a1 - m1 - [1, 0][self.carry_flag]
         
         # unsigned subtraction
-        result2 = a2 - m2 - self.carry_flag
+        result2 = a2 - m2 - [1, 0][self.carry_flag]
         
         self.accumulator = self.update_nz(result2)
         self.carry_flag = (result2 >= 0)