From 58e42fda81e42df6f5361bb2a2d6205e13e208e6 Mon Sep 17 00:00:00 2001
From: SarahW <pcem@pcem-emulator.co.uk>
Date: Fri, 26 Apr 2019 09:02:55 +0100
Subject: [PATCH] Don't enable RTC clock on speed change if RTC timer not
 enabled. Fixes crash when changing configuration with XT models.

---
 src/nvr.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/nvr.c b/src/nvr.c
index 3c68768..e9af3b6 100644
--- a/src/nvr.c
+++ b/src/nvr.c
@@ -65,6 +65,11 @@ void nvr_recalc()
 {
         int c;
 
+        if (!(nvrram[RTC_REGA] & RTC_RS))
+        {
+		timer_disable(&rtc_timer);
+                return;
+        }
         c = 1 << ((nvrram[RTC_REGA] & RTC_RS) - 1);
 	timer_set_delay_u64(&rtc_timer, (uint64_t)(RTCCONST * c));
 }