From cb487cd0e9c1d4805c2fd9e2f60d975b8f1b201c Mon Sep 17 00:00:00 2001
From: hap <happppp@users.noreply.github.com>
Date: Thu, 18 Jan 2018 20:37:32 +0100
Subject: [PATCH] sm511: update some notes (nw)

---
 src/devices/cpu/sm510/sm510op.cpp   |  2 +-
 src/devices/cpu/sm510/sm511core.cpp | 14 +++++++-------
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/devices/cpu/sm510/sm510op.cpp b/src/devices/cpu/sm510/sm510op.cpp
index c319b0ccdd4..654ce20a5d2 100644
--- a/src/devices/cpu/sm510/sm510op.cpp
+++ b/src/devices/cpu/sm510/sm510op.cpp
@@ -408,7 +408,7 @@ void sm510_base_device::op_rme()
 
 void sm510_base_device::op_tmel()
 {
-	// TMEL: skip next if rest signal is set, reset it
+	// TMEL: skip next if melody stop flag is set, reset it
 	m_skip = ((m_melody_rd & 2) != 0);
 	m_melody_rd &= ~2;
 }
diff --git a/src/devices/cpu/sm510/sm511core.cpp b/src/devices/cpu/sm510/sm511core.cpp
index 200740ee3e6..c830538efe7 100644
--- a/src/devices/cpu/sm510/sm511core.cpp
+++ b/src/devices/cpu/sm510/sm511core.cpp
@@ -93,20 +93,20 @@ void sm511_device::clock_melody()
 		return;
 
 	// tone cycle table (SM511/SM512 datasheet fig.5)
-	// cmd 0 = cmd, 1 = stop, > 13 = illegal(unknown)
+	// cmd 0 = rest, 1 = stop, > 13 = illegal(inactive?)
 	static const u8 lut_tone_cycles[4*16] =
 	{
-		0, 0, 7, 8, 8, 9, 9, 10,11,11,12,13,14,14, 7*2, 8*2,
-		0, 0, 8, 8, 9, 9, 10,11,11,12,13,13,14,15, 8*2, 8*2,
-		0, 0, 8, 8, 9, 9, 10,10,11,12,12,13,14,15, 8*2, 8*2,
-		0, 0, 8, 9, 9, 10,10,11,11,12,13,14,14,15, 8*2, 9*2
+		0, 0, 7, 8, 8, 9, 9, 10,11,11,12,13,14,14, 0, 0,
+		0, 0, 8, 8, 9, 9, 10,11,11,12,13,13,14,15, 0, 0,
+		0, 0, 8, 8, 9, 9, 10,10,11,12,12,13,14,15, 0, 0,
+		0, 0, 8, 9, 9, 10,10,11,11,12,13,14,14,15, 0, 0,
 	};
 
 	u8 cmd = m_melody_rom[m_melody_address] & 0x3f;
 	u8 out = 0;
 
 	// clock duty cycle if tone is active
-	if ((cmd & 0xf) > 1)
+	if ((cmd & 0xf) >= 2 && (cmd & 0xf) <= 13)
 	{
 		out = m_melody_duty_index & m_melody_rd & 1;
 		m_melody_duty_count++;
@@ -121,7 +121,7 @@ void sm511_device::clock_melody()
 	}
 	else if ((cmd & 0xf) == 1)
 	{
-		// rest tell signal
+		// set melody stop flag
 		m_melody_rd |= 2;
 	}