From b85cedc7186178d6b61b77efd888491a0ae85022 Mon Sep 17 00:00:00 2001
From: angelosa <salese_corp_ltd@email.it>
Date: Mon, 19 Feb 2018 14:23:48 +0100
Subject: [PATCH] model2.cpp: added 30 Hz renderer mode, fixes Virtua Striker
 timings [Angelo Salese]

---
 src/mame/drivers/model2.cpp | 15 +++++++++++++--
 src/mame/includes/model2.h  |  3 +++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/mame/drivers/model2.cpp b/src/mame/drivers/model2.cpp
index 8abeeb98212..b51c7b006a0 100644
--- a/src/mame/drivers/model2.cpp
+++ b/src/mame/drivers/model2.cpp
@@ -550,7 +550,14 @@ READ32_MEMBER(model2_state::fifoctl_r)
 
 READ32_MEMBER(model2_state::videoctl_r)
 {
-	return ((m_screen->frame_number() & 1) << 2) | (m_videocontrol & 3);
+	uint8_t framenum;
+	
+	if(m_render_mode == false)
+		framenum = (m_screen->frame_number() & 2) << 1;
+	else
+		framenum = (m_screen->frame_number() & 1) << 2;
+	
+	return (framenum) | (m_videocontrol & 3);
 }
 
 WRITE32_MEMBER(model2_state::videoctl_w)
@@ -1387,7 +1394,11 @@ WRITE32_MEMBER(model2_state::copro_w)
 
 WRITE32_MEMBER(model2_state::mode_w)
 {
-	osd_printf_debug("Mode = %08X\n", data);
+	// ---- -x-- (1) 60 Hz mode
+	//           (0) 30 Hz mode - skytargt, desert, vstriker, vcop
+	// ---- ---x Test Mode (Host can "access memories that are always being reloaded")
+	m_render_mode = bool(BIT(data,2));
+//	osd_printf_debug("Mode = %08X\n", data);
 }
 
 WRITE32_MEMBER(model2_state::model2o_tex_w0)
diff --git a/src/mame/includes/model2.h b/src/mame/includes/model2.h
index 76f89d6e205..84887e734b5 100644
--- a/src/mame/includes/model2.h
+++ b/src/mame/includes/model2.h
@@ -292,6 +292,9 @@ public:
 	
 protected:
 	virtual void video_start() override;
+	
+private:
+	bool m_render_mode;
 };