From 94c7d1b32cc23d5cf2c2b1c97e3b5a06d32051e3 Mon Sep 17 00:00:00 2001
From: "R. Belmont" <rb6502@users.noreply.github.com>
Date: Sat, 15 Oct 2011 18:46:25 +0000
Subject: [PATCH] 68681: work around core problem where a timer set to 0 hz
 locks up MAME (nw)

---
 src/emu/machine/68681.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/emu/machine/68681.c b/src/emu/machine/68681.c
index fca5530bca8..17b4d7cde37 100644
--- a/src/emu/machine/68681.c
+++ b/src/emu/machine/68681.c
@@ -574,6 +574,13 @@ READ8_DEVICE_HANDLER(duart68681_r)
 						//attotime rate = attotime::from_hz(duart68681->clock) * (16*duart68681->CTR.w.l);
 						attotime rate = attotime::from_hz(2*device->clock()/(2*16*16*duart68681->CTR.w.l));
 						//hz = ATTOSECONDS_TO_HZ(rate.attoseconds);
+
+						// workaround for maygay1b locking up MAME
+						if ((2*device->clock()/(2*16*16*duart68681->CTR.w.l)) == 0)
+						{
+							rate = attotime::from_hz(1);
+						}
+
 						duart68681->duart_timer->adjust(rate, 0, rate);
 					}
 					break;