diff --git a/src/mame/drivers/namcos22.cpp b/src/mame/drivers/namcos22.cpp
index a3f46510fe3..64490195aea 100644
--- a/src/mame/drivers/namcos22.cpp
+++ b/src/mame/drivers/namcos22.cpp
@@ -1203,10 +1203,8 @@ READ32_MEMBER(namcos22_state::namcos22_sci_r)
 	}
 }
 
-#if 0
 WRITE32_MEMBER(namcos22_state::namcos22_sci_w)
 {
-	COMBINE_DATA(&m_sci_regs[offset]);
 	/*
 	20020000  2 R/W RX Status
 	            0x01 : Frame Error
@@ -1234,7 +1232,6 @@ WRITE32_MEMBER(namcos22_state::namcos22_sci_w)
 	2002000e  2 W   TX FIFO Pointer (0x0000 - 0x1fff)
 	*/
 }
-#endif
 
 
 /* system controller (super system22)
@@ -1796,7 +1793,7 @@ void namcos22_state::namcos22_am(address_map &map)
 	 *     2002000c  2  R/W RX FIFO Pointer (0x0000 - 0x0fff)
 	 *     2002000e  2  W   TX FIFO Pointer (0x0000 - 0x1fff)
 	 */
-	map(0x20020000, 0x2002000f).r(FUNC(namcos22_state::namcos22_sci_r)).writeonly();
+	map(0x20020000, 0x2002000f).rw(FUNC(namcos22_state::namcos22_sci_r), FUNC(namcos22_state::namcos22_sci_w));
 
 	/**
 	 * System Controller: Interrupt Control, Peripheral Control
@@ -1937,7 +1934,7 @@ void namcos22_state::namcos22s_am(address_map &map)
 	map(0x000000, 0x3fffff).rom();
 	map(0x400000, 0x40001f).rw(FUNC(namcos22_state::namcos22_keycus_r), FUNC(namcos22_state::namcos22_keycus_w));
 	map(0x410000, 0x413fff).ram(); // C139 SCI buffer
-	map(0x420000, 0x42000f).r(FUNC(namcos22_state::namcos22_sci_r)).writeonly(); // C139 SCI registers
+	map(0x420000, 0x42000f).rw(FUNC(namcos22_state::namcos22_sci_r), FUNC(namcos22_state::namcos22_sci_w)); // C139 SCI registers
 	map(0x430000, 0x430003).w(FUNC(namcos22_state::namcos22_cpuleds_w));
 	map(0x440000, 0x440003).r(FUNC(namcos22_state::namcos22_dipswitch_r));
 	map(0x450008, 0x45000b).rw(FUNC(namcos22_state::namcos22_portbit_r), FUNC(namcos22_state::namcos22_portbit_w));
@@ -1968,6 +1965,7 @@ READ32_MEMBER(namcos22_state::namcos22_gun_r)
 	uint16_t xpos = ioport("LIGHTX")->read();
 	uint16_t ypos = ioport("LIGHTY")->read();
 	// ypos is not completely understood yet, there should be a difference between case 1 and 2
+	// game determines real y = 430004 + 430008
 
 	switch (offset)
 	{
@@ -3216,13 +3214,13 @@ static INPUT_PORTS_START( cybrcomm )
 	    end up needing to change again too
 	    Default key arrangement is based on dual-joystick 'Tank' arrangement found in Assault and CyberSled
 	*/
-	PORT_START("STICKY1")       /* VOLUME 0 */
+	PORT_START("STICKY1") /* VOLUME 1 */
 	PORT_BIT( 0xff, 0x7f, IPT_AD_STICK_Y ) PORT_MINMAX(0x47,0xb7) /* range based on test mode */ PORT_CODE_DEC(KEYCODE_I) PORT_CODE_INC(KEYCODE_K) PORT_SENSITIVITY(100) PORT_KEYDELTA(10) PORT_PLAYER(2) /* right joystick: vertical */
-	PORT_START("STICKY2")       /* VOLUME 0 */
-	PORT_BIT( 0xff, 0x7f, IPT_AD_STICK_Y ) PORT_MINMAX(0x47,0xb7) /* range based on test mode */ PORT_CODE_DEC(KEYCODE_E) PORT_CODE_INC(KEYCODE_D) PORT_SENSITIVITY(100) PORT_KEYDELTA(10) PORT_PLAYER(1) /* left joystick: vertical */
-	PORT_START("STICKX1")       /* VOLUME 0 */
+	PORT_START("STICKX1") /* VOLUME 2 */
 	PORT_BIT( 0xff, 0x7f, IPT_AD_STICK_X ) PORT_MINMAX(0x47,0xb7) /* range based on test mode */ PORT_CODE_DEC(KEYCODE_J) PORT_CODE_INC(KEYCODE_L) PORT_SENSITIVITY(100) PORT_KEYDELTA(10) PORT_PLAYER(2) /* right joystick: horizontal */
-	PORT_START("STICKX2")       /* VOLUME 0 */
+	PORT_START("STICKY2") /* VOLUME 3 */
+	PORT_BIT( 0xff, 0x7f, IPT_AD_STICK_Y ) PORT_MINMAX(0x47,0xb7) /* range based on test mode */ PORT_CODE_DEC(KEYCODE_E) PORT_CODE_INC(KEYCODE_D) PORT_SENSITIVITY(100) PORT_KEYDELTA(10) PORT_PLAYER(1) /* left joystick: vertical */
+	PORT_START("STICKX2") /* VOLUME 4 */
 	PORT_BIT( 0xff, 0x7f, IPT_AD_STICK_X ) PORT_MINMAX(0x47,0xb7) /* range based on test mode */ PORT_CODE_DEC(KEYCODE_S) PORT_CODE_INC(KEYCODE_F) PORT_SENSITIVITY(100) PORT_KEYDELTA(10) PORT_PLAYER(1) /* left joystick: horizontal */
 
 	PORT_START("DSW0")
@@ -3348,7 +3346,7 @@ static INPUT_PORTS_START( alpiner )
 	PORT_BIT( 0xff, 0x80, IPT_AD_STICK_X ) PORT_SENSITIVITY(100) PORT_KEYDELTA(4) PORT_NAME("Steps Swing")
 
 	PORT_START("ADC.1")
-	PORT_BIT( 0xff, 0x80, IPT_AD_STICK_Y ) PORT_SENSITIVITY(100) PORT_KEYDELTA(4) PORT_NAME("Steps Edge")
+	PORT_BIT( 0xff, 0x80, IPT_AD_STICK_X ) PORT_SENSITIVITY(100) PORT_KEYDELTA(4) PORT_PLAYER(2) PORT_NAME("Steps Edge")
 INPUT_PORTS_END
 
 static INPUT_PORTS_START( airco22 )
@@ -3368,22 +3366,22 @@ static INPUT_PORTS_START( airco22 )
 	PORT_BIT( 0x02, IP_ACTIVE_LOW, IPT_UNKNOWN )
 	PORT_BIT( 0x04, IP_ACTIVE_LOW, IPT_SERVICE1 )
 	PORT_SERVICE( 0x08, IP_ACTIVE_LOW )
-	PORT_BIT( 0x10, IP_ACTIVE_LOW, IPT_BUTTON2 ) /* Missile */
-	PORT_BIT( 0x20, IP_ACTIVE_LOW, IPT_BUTTON1 ) /* Gun */
-	PORT_BIT( 0x40, IP_ACTIVE_LOW, IPT_START1 )
+	PORT_BIT( 0x10, IP_ACTIVE_LOW, IPT_BUTTON2 ) PORT_NAME("Missile Button")
+	PORT_BIT( 0x20, IP_ACTIVE_LOW, IPT_BUTTON1 ) PORT_NAME("Gun Trigger")
+	PORT_BIT( 0x40, IP_ACTIVE_LOW, IPT_START1 ) // also view-change function
 	PORT_BIT( 0x80, IP_ACTIVE_LOW, IPT_UNKNOWN )
 
 	PORT_START("MCUP5B")
 	PORT_BIT( 0xff, IP_ACTIVE_LOW, IPT_UNKNOWN )
 
 	PORT_START("ADC.0")
-	PORT_BIT( 0xff, 0x80, IPT_AD_STICK_X ) PORT_MINMAX(0x40, 0xc0) PORT_SENSITIVITY(100) PORT_KEYDELTA(4)
+	PORT_BIT( 0xff, 0x80, IPT_AD_STICK_X ) PORT_MINMAX(0x40, 0xc0) PORT_SENSITIVITY(100) PORT_KEYDELTA(2)
 
 	PORT_START("ADC.1")
-	PORT_BIT( 0xff, 0x80, IPT_AD_STICK_Y ) PORT_MINMAX(0x40, 0xc0) PORT_SENSITIVITY(100) PORT_KEYDELTA(4)
+	PORT_BIT( 0xff, 0x80, IPT_AD_STICK_Y ) PORT_MINMAX(0x40, 0xc0) PORT_SENSITIVITY(100) PORT_KEYDELTA(2)
 
-	PORT_START("ADC.2")
-	PORT_BIT( 0xff, 0x80, IPT_AD_STICK_Z ) PORT_MINMAX(0x40, 0xc0) PORT_SENSITIVITY(100) PORT_KEYDELTA(4)
+	PORT_START("ADC.2") // throttle stick auto-centers
+	PORT_BIT( 0xff, 0x80, IPT_AD_STICK_Z ) PORT_MINMAX(0x40, 0xc0) PORT_SENSITIVITY(100) PORT_KEYDELTA(2) PORT_NAME("Throttle Stick")
 INPUT_PORTS_END
 
 static INPUT_PORTS_START( cybrcycc )
@@ -3706,12 +3704,12 @@ static const gfx_layout namcos22_cg_layout =
 #undef XOR
 
 static GFXDECODE_START( gfx_namcos22 )
-	GFXDECODE_ENTRY( nullptr,      0, namcos22_cg_layout,   0, 0x800 )
+	GFXDECODE_ENTRY( nullptr,   0, namcos22_cg_layout,   0, 0x800 )
 	GFXDECODE_ENTRY( "textile", 0, texture_tile_layout,  0, 0x80 )
 GFXDECODE_END
 
 static GFXDECODE_START( gfx_super )
-	GFXDECODE_ENTRY( nullptr,      0, namcos22_cg_layout,   0, 0x800 )
+	GFXDECODE_ENTRY( nullptr,   0, namcos22_cg_layout,   0, 0x800 )
 	GFXDECODE_ENTRY( "textile", 0, texture_tile_layout,  0, 0x80 )
 	GFXDECODE_ENTRY( "sprite",  0, sprite_layout,        0, 0x80 )
 GFXDECODE_END
diff --git a/src/mame/includes/namcos22.h b/src/mame/includes/namcos22.h
index 899dc2a0c6a..d05ff6ade3c 100644
--- a/src/mame/includes/namcos22.h
+++ b/src/mame/includes/namcos22.h
@@ -333,6 +333,7 @@ private:
 	DECLARE_READ16_MEMBER(dsp_slave_portb_r);
 	DECLARE_WRITE16_MEMBER(dsp_slave_portb_w);
 	DECLARE_READ32_MEMBER(namcos22_sci_r);
+	DECLARE_WRITE32_MEMBER(namcos22_sci_w);
 	DECLARE_READ8_MEMBER(namcos22_system_controller_r);
 	DECLARE_WRITE8_MEMBER(namcos22s_system_controller_w);
 	DECLARE_WRITE8_MEMBER(namcos22_system_controller_w);
diff --git a/src/mame/video/namcos22.cpp b/src/mame/video/namcos22.cpp
index 398156a3d58..e85f9f2bcb4 100644
--- a/src/mame/video/namcos22.cpp
+++ b/src/mame/video/namcos22.cpp
@@ -1043,7 +1043,7 @@ void namcos22_state::blit_single_quad(bitmap_rgb32 &bitmap, uint32_t color, uint
 			else if (m_SurfaceNormalFormat == 0x4000)
 				m_LitSurfaceIndex++;
 			else
-				logerror("unknown normal format: 0x%x\n", m_SurfaceNormalFormat);
+				logerror("blit_single_quad:unknown normal format: 0x%x\n", m_SurfaceNormalFormat);
 		}
 		else if (packetformat & 0x40)
 		{
@@ -1355,7 +1355,7 @@ void namcos22_state::slavesim_handle_200002(bitmap_rgb32 &bitmap, const int32_t
 	}
 	else if (m_PrimitiveID != 0 && m_PrimitiveID != 2)
 	{
-		logerror("slavesim_handle_200002:unk code=0x%x\n", m_PrimitiveID);
+		logerror("slavesim_handle_200002:unknown code=0x%x\n", m_PrimitiveID);
 		// ridgerac title screen waving flag: 0x5
 	}
 }
@@ -1396,7 +1396,6 @@ void namcos22_state::slavesim_handle_233002(const int32_t *src)
 void namcos22_state::simulate_slavedsp(bitmap_rgb32 &bitmap)
 {
 	const int32_t *src = 0x300 + (int32_t *)m_polygonram.target();
-	int16_t len;
 
 	if (m_is_ss22)
 	{
@@ -1409,9 +1408,15 @@ void namcos22_state::simulate_slavedsp(bitmap_rgb32 &bitmap)
 
 	for (;;)
 	{
-		int16_t next;
+		/* hackery! commands should be streamed, not parsed here */
 		m_PrimitiveID = *src++;
-		len  = (int16_t)*src++;
+		uint16_t len = *src++;
+		int32_t index = src - (int32_t *)m_polygonram.target();
+		if ((index + len) >= 0x7fff)
+		{
+			logerror("simulate_slavedsp:buffer overflow len=0x%x code=0x%x addr=0x%x\n", len, m_PrimitiveID, index);
+			return;
+		}
 
 		switch (len)
 		{
@@ -1432,27 +1437,35 @@ void namcos22_state::simulate_slavedsp(bitmap_rgb32 &bitmap)
 				break;
 
 			default:
-				logerror("unk 3d data(%d) addr=0x%x!", len, (int)(src-(int32_t*)m_polygonram.target()));
+			{
+				std::string polydata;
+				int i = 0;
+				for (; i < len && i < 0x20; i++)
 				{
-					int i;
-					for (i = 0; i < len; i++)
-					{
-						logerror(" %06x", src[i] & 0xffffff);
-					}
-					logerror("\n");
+					char h[8];
+					sprintf(h, " %06x", src[i] & 0xffffff);
+					polydata += h;
 				}
+				if (i < len)
+					polydata += " (...)";
+				logerror("simulate_slavedsp:unknown 3d data len=0x%x code=0x%x addr=0x%x!%s\n", len, m_PrimitiveID, index, polydata);
 				return;
+			}
 		}
 
-		/* hackery! commands should be streamed, not parsed here */
 		src += len;
 		src++; /* always 0xffff */
-		next = (int16_t)*src++; /* link to next command */
-		if ((next & 0x7fff) != (src - (int32_t *)m_polygonram.target()))
+		uint16_t next = 0x7fff & *src++; /* link to next command */
+		if (next != (index + len + 1 + 1))
 		{
 			/* end of list */
 			break;
 		}
+		if (next == 0x7fff)
+		{
+			logerror("simulate_slavedsp:buffer overflow next=0x7fff\n");
+			return;
+		}
 	}
 }