diff -r 655ff3f6352d -r 2a1a9ef8002f src/dev/mc146818.cc
--- a/src/dev/mc146818.cc	Wed Feb 11 10:48:53 2015 -0800
+++ b/src/dev/mc146818.cc	Wed Mar 11 11:56:45 2015 +0100
@@ -127,8 +127,11 @@
 {
     assert(!event.scheduled());
     assert(!tickEvent.scheduled());
-    schedule(event, curTick() + event.offset);
-    schedule(tickEvent, curTick() + tickEvent.offset);
+
+    if (stat_regB.pie)
+        schedule(event, curTick() + event.offset);
+    if (!rega_dv_disabled(stat_regA))
+        schedule(tickEvent, curTick() + tickEvent.offset);
 }
 
 void