From 24f87966144cf042ce112e70081b12fadf56d603 Mon Sep 17 00:00:00 2001
From: hap <happppp@users.noreply.github.com>
Date: Sun, 19 Jul 2015 02:23:00 +0200
Subject: [PATCH] added RAM

---
 src/mess/drivers/tb303.c | 111 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 110 insertions(+), 1 deletion(-)

diff --git a/src/mess/drivers/tb303.c b/src/mess/drivers/tb303.c
index 1631ce2b0a6..9e2fd110b2a 100644
--- a/src/mess/drivers/tb303.c
+++ b/src/mess/drivers/tb303.c
@@ -28,6 +28,18 @@ public:
 
 	required_device<cpu_device> m_maincpu;
 	required_device<timer_device> m_t3_off_timer;
+	
+	UINT8 m_mcu_port[9]; // MCU port A-I write data
+	
+	UINT8 m_ram[0xc00];
+	UINT16 m_ram_address;
+	bool m_ram_ce;
+	bool m_ram_we;
+
+	DECLARE_WRITE8_MEMBER(ram_w);
+	DECLARE_READ8_MEMBER(ram_r);
+	DECLARE_WRITE8_MEMBER(strobe_w);
+	void refresh_ram();
 
 	TIMER_DEVICE_CALLBACK_MEMBER(t3_clock);
 	TIMER_DEVICE_CALLBACK_MEMBER(t3_off);
@@ -36,6 +48,12 @@ public:
 };
 
 
+/***************************************************************************
+
+  Timer/Interrupt
+
+***************************************************************************/
+
 // T2 to MCU CLK: LC circuit, stable sine wave, 2.2us interval
 #define TB303_T2_CLOCK_HZ   454545 /* in hz */
 
@@ -56,6 +74,75 @@ TIMER_DEVICE_CALLBACK_MEMBER(tb303_state::t3_clock)
 
 
 
+/***************************************************************************
+
+  I/O
+
+***************************************************************************/
+
+void tb303_state::refresh_ram()
+{
+	// MCU E2,E3 goes through a 4556 IC(pin 14,13) to one of uPD444 _CE:
+	// _Q0: N/C, _Q1: IC-5, _Q2: IC-3, _Q3: IC-4
+	m_ram_ce = true;
+	UINT8 hi = 0;
+	switch (m_mcu_port[NEC_UCOM4_PORTE] >> 2 & 3)
+	{
+		case 0: m_ram_ce = false; break;
+		case 1: hi = 0; break;
+		case 2: hi = 1; break;
+		case 3: hi = 2; break;
+	}
+	
+	if (m_ram_ce)
+	{
+		// _WE must be high(read mode) for address transitions
+		if (!m_ram_we)
+			m_ram_address = hi << 10 | (m_mcu_port[NEC_UCOM4_PORTE] << 8 & 0x300) | m_mcu_port[NEC_UCOM4_PORTF] << 4 | m_mcu_port[NEC_UCOM4_PORTD];
+		else
+			m_ram[m_ram_address] = m_mcu_port[NEC_UCOM4_PORTC];
+	}
+
+	// to switchboard pin 19-22
+	//..
+}
+
+WRITE8_MEMBER(tb303_state::ram_w)
+{
+	// MCU C: RAM data
+	// MCU D,F,E: RAM address
+	m_mcu_port[offset] = data;
+	refresh_ram();
+	
+	// MCU D,F01: pitch data
+	//..
+}
+
+READ8_MEMBER(tb303_state::ram_r)
+{
+	// MCU C: RAM data
+	if (m_ram_ce && !m_ram_we)
+		return m_ram[m_ram_address];
+	else
+		return 0;
+}
+
+WRITE8_MEMBER(tb303_state::strobe_w)
+{
+	// MCU I0: RAM _WE
+	m_ram_we = (data & 1) ? false : true;
+	refresh_ram();
+	
+	// MCU I1: pitch data latch strobe
+	// MCU I2: gate signal
+}
+
+
+/***************************************************************************
+
+  Inputs
+
+***************************************************************************/
 
 static INPUT_PORTS_START( tb303 )
 INPUT_PORTS_END
@@ -70,13 +157,35 @@ INPUT_PORTS_END
 
 void tb303_state::machine_start()
 {
+	// zerofill
+	memset(m_mcu_port, 0, sizeof(m_mcu_port));
+	memset(m_ram, 0, sizeof(m_ram));
+	m_ram_address = 0;
+	m_ram_ce = false;
+	m_ram_we = false;
+	
+	// register for savestates
+	save_item(NAME(m_mcu_port));
+	save_item(NAME(m_ram));
+	save_item(NAME(m_ram_address));
+	save_item(NAME(m_ram_ce));
+	save_item(NAME(m_ram_we));
 }
 
-
 static MACHINE_CONFIG_START( tb303, tb303_state )
 
 	/* basic machine hardware */
 	MCFG_CPU_ADD("maincpu", NEC_D650, TB303_T2_CLOCK_HZ)
+	//MCFG_UCOM4_READ_A_CB
+	//MCFG_UCOM4_READ_B_CB
+	MCFG_UCOM4_READ_C_CB(READ8(tb303_state, ram_r))
+	MCFG_UCOM4_WRITE_C_CB(WRITE8(tb303_state, ram_w))
+	MCFG_UCOM4_WRITE_D_CB(WRITE8(tb303_state, ram_w))
+	MCFG_UCOM4_WRITE_E_CB(WRITE8(tb303_state, ram_w))
+	MCFG_UCOM4_WRITE_F_CB(WRITE8(tb303_state, ram_w))
+	//MCFG_UCOM4_WRITE_G_CB
+	//MCFG_UCOM4_WRITE_H_CB
+	MCFG_UCOM4_WRITE_I_CB(WRITE8(tb303_state, strobe_w))
 
 	MCFG_TIMER_DRIVER_ADD_PERIODIC("t3_clock", tb303_state, t3_clock, TB303_T3_CLOCK)
 	MCFG_TIMER_START_DELAY(TB303_T3_CLOCK)