diff --git a/PDP10/kl10_fe.c b/PDP10/kl10_fe.c
index 940066f..dfb5dda 100644
--- a/PDP10/kl10_fe.c
+++ b/PDP10/kl10_fe.c
@@ -302,6 +302,7 @@ REG  dte_reg[] = {
     {SAVEDATA(CTYIN, cty_in) },
     {SAVEDATA(CTYOUT, cty_out) },
     {HRDATA(DONE, cty_done, 8), REG_HRO},
+    {HRDATAD(WRU, sim_int_char, 8, "interrupt character") },
     { 0 },
     };
 
diff --git a/PDP10/kx10_cty.c b/PDP10/kx10_cty.c
index d987f8c..c79af5c 100644
--- a/PDP10/kx10_cty.c
+++ b/PDP10/kx10_cty.c
@@ -74,8 +74,13 @@ MTAB cty_mod[] = {
     { 0 }
     };
 
+REG cty_reg[] = {
+    { HRDATAD (WRU, sim_int_char, 8, "interrupt character") },
+    { 0 }
+    };
+
 DEVICE cty_dev = {
-    "CTY", cty_unit, NULL, cty_mod,
+    "CTY", cty_unit, cty_reg, cty_mod,
     2, 10, 31, 1, 8, 8,
     NULL, NULL, &cty_reset,
     NULL, NULL, NULL, &cty_dib, DEV_DEBUG, 0, dev_debug,