diff --git a/doc/simh.doc b/doc/simh.doc
index 6e39cea8..03bb114d 100644
Binary files a/doc/simh.doc and b/doc/simh.doc differ
diff --git a/sim_console.c b/sim_console.c
index 41558b26..6a0674b7 100644
--- a/sim_console.c
+++ b/sim_console.c
@@ -182,6 +182,13 @@ int32 sim_del_char = '\b';                              /* delete character */
 #else
 int32 sim_del_char = 0177;
 #endif
+t_bool sim_signaled_int_char                            /* WRU character detected by signal while running */
+#if defined (_WIN32) || defined (_VMS) || defined (__CYGWIN__)
+                             = FALSE;
+#else
+                             = TRUE;
+#endif
+uint32 sim_last_poll_kbd_time;                          /* time when sim_poll_kbd was called */
 extern TMLN *sim_oline;                                 /* global output socket */
 
 static t_stat sim_con_poll_svc (UNIT *uptr);                /* console connection poll routine */
@@ -2835,6 +2842,7 @@ t_stat sim_poll_kbd (void)
 {
 t_stat c;
 
+sim_last_poll_kbd_time = sim_os_msec ();                    /* record when this poll happened */
 if (sim_send_poll_data (&sim_con_send, &c))                 /* injected input characters available? */
     return c;
 if (!sim_rem_master_mode) {
diff --git a/sim_console.h b/sim_console.h
index 6f27d99c..37a1fe06 100644
--- a/sim_console.h
+++ b/sim_console.h
@@ -127,12 +127,14 @@ int32 sim_tt_outcvt (int32 c, uint32 mode);
 t_stat sim_tt_settabs (UNIT *uptr, int32 val, CONST char *cptr, void *desc);
 t_stat sim_tt_showtabs (FILE *st, UNIT *uptr, int32 val, CONST void *desc);
 
-extern int32 sim_rem_cmd_active_line;                       /* command in progress on line # */
+extern int32 sim_rem_cmd_active_line;   /* command in progress on line # */
 
-extern int32 sim_int_char;                                  /* interrupt character */
-extern int32 sim_brk_char;                                  /* break character */
-extern int32 sim_tt_pchar;                                  /* printable character mask */
-extern int32 sim_del_char;                                  /* delete character */
+extern int32 sim_int_char;              /* interrupt character */
+extern int32 sim_brk_char;              /* break character */
+extern int32 sim_tt_pchar;              /* printable character mask */
+extern int32 sim_del_char;              /* delete character */
+extern t_bool sim_signaled_int_char;    /* WRU character detected by signal while running  */
+extern uint32 sim_last_poll_kbd_time;   /* time when sim_poll_kbd was called */
 
 #ifdef  __cplusplus
 }
diff --git a/sim_timer.c b/sim_timer.c
index 8c773037..b1207165 100644
--- a/sim_timer.c
+++ b/sim_timer.c
@@ -987,6 +987,11 @@ if (sim_calb_tmr != tmr) {
     return rtc->currd;
     }
 new_rtime = sim_os_msec ();                         /* wall time */
+if (!sim_signaled_int_char && 
+    ((new_rtime - sim_last_poll_kbd_time) > 500)) {
+    sim_debug (DBG_CAL, &sim_timer_dev, "sim_rtcn_calb(tmr=%d) gratuitious keyboard poll after %d msecs\n", tmr, (int)(new_rtime - sim_last_poll_kbd_time));
+    (void)sim_poll_kbd ();
+    }
 ++rtc->calibrations;                                /* count calibrations */
 sim_debug (DBG_TRC, &sim_timer_dev, "sim_rtcn_calb(ticksper=%d, tmr=%d)\n", ticksper, tmr);
 if (new_rtime < rtc->rtime) {                       /* time running backwards? */