From 7fd5b507d5d89c00da899a17e06cc8fea34653c0 Mon Sep 17 00:00:00 2001
From: Neil Webber <neil@webber.com>
Date: Mon, 1 Apr 2024 07:56:22 -0500
Subject: [PATCH] missing import and fix _shifter when NN=0 per 1981 book.
 Issue Misc #10

---
 op07.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/op07.py b/op07.py
index ca2c743..0143ef0 100644
--- a/op07.py
+++ b/op07.py
@@ -34,6 +34,8 @@
 # op076 is the commercial instruction set
 #
 
+from pdptraps import PDPTraps
+
 
 def op070_mul(cpu, inst):
     dstreg = (inst & 0o000700) >> 6
@@ -152,7 +154,7 @@ def _shifter(cpu, value, shift, *, opsize):
         cpu.psw_n = vsign
         cpu.psw_z = (value == 0)
         cpu.psw_v = 0
-        # C is not altered
+        cpu.psw_c = 0         # per 1981 PDP11 Processor Handbook
         return value
     elif shift > 31:       # right shift
         # sign extend if appropriate, so the sign propagates