diff --git a/modules/pdp11/lib/pc11.js b/modules/pdp11/lib/pc11.js
index e1e6f74c8..b8f886396 100644
--- a/modules/pdp11/lib/pc11.js
+++ b/modules/pdp11/lib/pc11.js
@@ -90,6 +90,9 @@ PC11.prototype.initBus = function(cmp, bus, cpu, dbg)
     this.bus = bus;
     this.cpu = cpu;
     this.dbg = dbg;
+
+    bus.addIOTable(this, PC11.UNIBUS_IOTABLE);
+
     this.setReady();
 };