diff -r f72bd92d39d2 -r 0430ff95bb54 src/dev/mc146818.cc
--- a/src/dev/mc146818.cc	Tue Jan 13 18:18:29 2015 +0100
+++ 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