diff --git a/src/devices/machine/6840ptm.cpp b/src/devices/machine/6840ptm.cpp
index bbf9a57ce18..5117531c767 100644
--- a/src/devices/machine/6840ptm.cpp
+++ b/src/devices/machine/6840ptm.cpp
@@ -115,7 +115,7 @@ void ptm6840_device::device_start()
 	save_item(NAME(m_t3_divisor));
 	save_item(NAME(m_t3_scaler));
 	save_item(NAME(m_internal_clock));
-	save_item(NAME(m_IRQ));
+	save_item(NAME(m_irq));
 
 	save_item(NAME(m_control_reg));
 	save_item(NAME(m_output));
@@ -142,7 +142,7 @@ void ptm6840_device::device_reset()
 	m_status_reg             = 0;
 	m_t3_divisor             = 1;
 	m_status_read_since_int = 0;
-	m_IRQ                   = 0;
+	m_irq                   = 0;
 	m_t3_scaler             = 0;
 	for (int i = 0; i < 3; i++)
 	{
@@ -175,7 +175,7 @@ void ptm6840_device::subtract_from_counter(int counter, int count)
 	double clock;
 
 	// Determine the clock frequency for this timer
-	if (m_control_reg[counter] & 0x02)
+	if (m_control_reg[counter] & INTERNAL_CLK_EN)
 	{
 		clock = m_internal_clock;
 	}
@@ -185,7 +185,7 @@ void ptm6840_device::subtract_from_counter(int counter, int count)
 	}
 
 	// Dual-byte mode
-	if (m_control_reg[counter] & 0x04)
+	if (m_control_reg[counter] & COUNT_MODE_8BIT)
 	{
 		int lsb = m_counter[counter] & 0xff;
 		int msb = m_counter[counter] >> 8;
@@ -279,24 +279,24 @@ void ptm6840_device::tick(int counter, int count)
 
 void ptm6840_device::update_interrupts()
 {
-	int new_state = ((m_status_reg & 0x01) && (m_control_reg[0] & 0x40)) ||
-					((m_status_reg & 0x02) && (m_control_reg[1] & 0x40)) ||
-					((m_status_reg & 0x04) && (m_control_reg[2] & 0x40));
+	int new_state = ((m_status_reg & TIMER1_IRQ) && (m_control_reg[0] & INTERRUPT_EN)) ||
+					((m_status_reg & TIMER2_IRQ) && (m_control_reg[1] & INTERRUPT_EN)) ||
+					((m_status_reg & TIMER3_IRQ) && (m_control_reg[2] & INTERRUPT_EN));
 
-	if (new_state != m_IRQ)
+	if (new_state != m_irq)
 	{
-		m_IRQ = new_state;
+		m_irq = new_state;
 
-		if (m_IRQ)
+		if (m_irq)
 		{
-			m_status_reg |= 0x80;
+			m_status_reg |= ANY_IRQ;
 		}
 		else
 		{
-			m_status_reg &= ~0x80;
+			m_status_reg &= ~ANY_IRQ;
 		}
 
-		m_irq_cb(m_IRQ);
+		m_irq_cb(m_irq);
 	}
 }
 
@@ -318,7 +318,7 @@ UINT16 ptm6840_device::compute_counter( int counter ) const
 	}
 
 	// determine the clock frequency for this timer
-	if (m_control_reg[counter] & 0x02)
+	if (m_control_reg[counter] & INTERNAL_CLK_EN)
 	{
 		clock = m_internal_clock;
 		PLOG(("MC6840 #%s: %d internal clock freq %f \n", tag(), counter, clock));
@@ -332,7 +332,7 @@ UINT16 ptm6840_device::compute_counter( int counter ) const
 	int remaining = (m_timer[counter]->remaining() * clock).as_double();
 
 	// Adjust the count for dual byte mode
-	if (m_control_reg[counter] & 0x04)
+	if (m_control_reg[counter] & COUNT_MODE_8BIT)
 	{
 		int divisor = (m_counter[counter] & 0xff) + 1;
 		int msb = remaining / divisor;
@@ -356,8 +356,12 @@ void ptm6840_device::reload_count(int idx)
 	// Copy the latched value in
 	m_counter[idx] = m_latch[idx];
 
+	// If reset is held, don't start counting
+	if (m_control_reg[0] & RESET_TIMERS)
+		return;
+
 	// Determine the clock frequency for this timer
-	if (m_control_reg[idx] & 0x02)
+	if (m_control_reg[idx] & INTERNAL_CLK_EN)
 	{
 		clock = m_internal_clock;
 		PLOG(("MC6840 #%s: %d internal clock freq %f \n", tag(), idx, clock));
@@ -370,7 +374,7 @@ void ptm6840_device::reload_count(int idx)
 
 	// Determine the number of clock periods before we expire
 	int count = m_counter[idx];
-	if (m_control_reg[idx] & 0x04)
+	if (m_control_reg[idx] & COUNT_MODE_8BIT)
 	{
 		count = ((count >> 8) + 1) * ((count & 0xff) + 1);
 	}
@@ -410,7 +414,7 @@ void ptm6840_device::reload_count(int idx)
 	PLOG(("MC6840 #%s: reload_count(%d): output = %f\n", tag(), idx, duration.as_double()));
 
 #if 0
-	if (!(m_control_reg[idx] & 0x02))
+	if (!(m_control_reg[idx] & INTERNAL_CLK_EN))
 	{
 		if (!m_external_clock[idx])
 		{
@@ -504,9 +508,9 @@ WRITE8_MEMBER( ptm6840_device::write )
 		case PTM_6840_CTRL1:
 		case PTM_6840_CTRL2:
 		{
-			int idx = (offset == 1) ? 1 : (m_control_reg[1] & 0x01) ? 0 : 2;
+			int idx = (offset == 1) ? 1 : (m_control_reg[1] & CR1_SELECT) ? 0 : 2;
 			UINT8 diffs = data ^ m_control_reg[idx];
-			m_t3_divisor = (m_control_reg[2] & 0x01) ? 8 : 1;
+			m_t3_divisor = (m_control_reg[2] & T3_PRESCALE_EN) ? 8 : 1;
 			m_mode[idx] = (data >> 3) & 0x07;
 			m_control_reg[idx] = data;
 
@@ -515,7 +519,10 @@ WRITE8_MEMBER( ptm6840_device::write )
 			PLOG(("value            = %04X\n", m_control_reg[idx]));
 			PLOG(("t3divisor        = %d\n", m_t3_divisor));
 
-			if (!(m_control_reg[idx] & 0x80 ))
+			if (diffs & INTERRUPT_EN)
+				update_interrupts();
+
+			if (!(m_control_reg[idx] & COUNT_OUT_EN))
 			{
 				// Output cleared
 				switch (idx)
@@ -531,11 +538,12 @@ WRITE8_MEMBER( ptm6840_device::write )
 						break;
 				}
 			}
+
 			// Reset?
-			if (idx == 0 && (diffs & 0x01))
+			if (idx == 0 && (diffs & RESET_TIMERS))
 			{
 				// Holding reset down
-				if (data & 0x01)
+				if (data & RESET_TIMERS)
 				{
 					PLOG(("MC6840 #%s : Timer reset\n", tag()));
 					for (int i = 0; i < 3; i++)
@@ -555,12 +563,12 @@ WRITE8_MEMBER( ptm6840_device::write )
 
 				m_status_reg = 0;
 				update_interrupts();
+			}
 
-				// Changing the clock source? (e.g. Zwackery)
-				if (diffs & 0x02)
-				{
-					reload_count(idx);
-				}
+			// Changing the clock source? (e.g. Zwackery)
+			if (diffs & INTERNAL_CLK_EN)
+			{
+				reload_count(idx);
 			}
 			break;
 		}
@@ -611,9 +619,9 @@ void ptm6840_device::timeout(int idx)
 	m_status_read_since_int &= ~(1 << idx);
 	update_interrupts();
 
-	if ( m_control_reg[idx] & 0x80 )
+	if (m_control_reg[idx] & COUNT_OUT_EN)
 	{
-		if ((m_mode[idx] == 0)||(m_mode[idx] == 2))
+		if (m_mode[idx] == 0 || m_mode[idx] == 2)
 		{
 			m_output[idx] = m_output[idx] ? 0 : 1;
 			PLOG(("**ptm6840 %s t%d output %d **\n", tag(), idx, m_output[idx]));
@@ -694,7 +702,7 @@ void ptm6840_device::set_clock(int idx, int state)
 {
 	m_clk[idx] = state;
 
-	if (!(m_control_reg[idx] & 0x02))
+	if (!(m_control_reg[idx] & INTERNAL_CLK_EN))
 	{
 		if (state)
 		{
@@ -716,7 +724,7 @@ void ptm6840_device::set_ext_clock(int counter, double clock)
 {
 	m_external_clock[counter] = clock;
 
-	if (!(m_control_reg[counter] & 0x02))
+	if (!(m_control_reg[counter] & INTERNAL_CLK_EN))
 	{
 		if (!m_external_clock[counter])
 		{
@@ -732,7 +740,7 @@ void ptm6840_device::set_ext_clock(int counter, double clock)
 		// Determine the number of clock periods before we expire
 		count = m_counter[counter];
 
-		if (m_control_reg[counter] & 0x04)
+		if (m_control_reg[counter] & COUNT_MODE_8BIT)
 		{
 			count = ((count >> 8) + 1) * ((count & 0xff) + 1);
 		}
diff --git a/src/devices/machine/6840ptm.h b/src/devices/machine/6840ptm.h
index 5eb1cdd211c..4165bf5db28 100644
--- a/src/devices/machine/6840ptm.h
+++ b/src/devices/machine/6840ptm.h
@@ -59,7 +59,7 @@ public:
 	template<class _Object> static devcb_base &set_irq_callback(device_t &device, _Object object) { return downcast<ptm6840_device &>(device).m_irq_cb.set_callback(object); }
 
 	int status(int clock) const { return m_enabled[clock]; } // get whether timer is enabled
-	int irq_state() const { return m_IRQ; }                 // get IRQ state
+	int irq_state() const { return m_irq; }                 // get IRQ state
 	UINT16 count(int counter) const { return compute_counter(counter); }    // get counter value
 	void set_ext_clock(int counter, double clock);  // set clock frequency
 	int ext_clock(int counter) const { return m_external_clock[counter]; }  // get clock frequency
@@ -108,6 +108,25 @@ private:
 		PTM_6840_LSB3    = 7
 	};
 
+	enum
+	{
+		RESET_TIMERS	= 0x01,
+		CR1_SELECT		= 0x01,
+		T3_PRESCALE_EN 	= 0x01,
+		INTERNAL_CLK_EN	= 0x02,
+		COUNT_MODE_8BIT	= 0x04,
+		INTERRUPT_EN	= 0x40,
+		COUNT_OUT_EN	= 0x80
+	};
+
+	enum
+	{
+		TIMER1_IRQ	= 0x01,
+		TIMER2_IRQ	= 0x02,
+		TIMER3_IRQ	= 0x04,
+		ANY_IRQ		= 0x80
+	};
+
 	double m_internal_clock;
 	double m_external_clock[3];
 
@@ -125,7 +144,7 @@ private:
 	UINT8 m_fired[3];
 	UINT8 m_t3_divisor;
 	UINT8 m_t3_scaler;
-	UINT8 m_IRQ;
+	UINT8 m_irq;
 	UINT8 m_status_reg;
 	UINT8 m_status_read_since_int;
 	UINT8 m_lsb_buffer;
diff --git a/src/mame/drivers/cmi.cpp b/src/mame/drivers/cmi.cpp
index f69e736e861..2279fe5477d 100644
--- a/src/mame/drivers/cmi.cpp
+++ b/src/mame/drivers/cmi.cpp
@@ -290,6 +290,8 @@ MACHINE_CONFIG_FRAGMENT( cmi01a_device )
 	MCFG_DEVICE_ADD("cmi01a_pia_0", PIA6821, 0) // pia_cmi01a_1_config
 	MCFG_PIA_CA2_HANDLER(WRITELINE(cmi01a_device, cmi01a_1_ca2_w))
 	MCFG_PIA_CB2_HANDLER(WRITELINE(cmi01a_device, cmi01a_1_cb2_w))
+	MCFG_PIA_IRQA_HANDLER(WRITELINE(cmi01a_device, ch_int))
+	MCFG_PIA_IRQB_HANDLER(WRITELINE(cmi01a_device, ch_int))
 
 	MCFG_DEVICE_ADD("cmi01a_pia_1", PIA6821, 0) // pia_cmi01a_2_config
 	MCFG_PIA_READCA1_HANDLER(READLINE(cmi01a_device, zx_r))
@@ -300,7 +302,10 @@ MACHINE_CONFIG_FRAGMENT( cmi01a_device )
 	MCFG_PIA_IRQB_HANDLER(WRITELINE(cmi01a_device, ch_int))
 
 	MCFG_DEVICE_ADD("cmi01a_ptm", PTM6840, 0) // ptm_cmi01a_config
+	MCFG_PTM6840_INTERNAL_CLOCK(2000000)
+	MCFG_PTM6840_EXTERNAL_CLOCKS(250000, 500000, 500000)
 	MCFG_PTM6840_OUT0_CB(WRITE8(cmi01a_device, cmi01a_ptm_c0))
+	MCFG_PTM6840_IRQ_CB(WRITELINE(cmi01a_device, ch_int))
 MACHINE_CONFIG_END
 
 machine_config_constructor cmi01a_device::device_mconfig_additions() const
@@ -477,6 +482,7 @@ public:
 	DECLARE_READ8_MEMBER( cmi02_r );
 	DECLARE_WRITE8_MEMBER( cmi02_w );
 	DECLARE_WRITE8_MEMBER( master_tune_w );
+	DECLARE_WRITE_LINE_MEMBER( cmi02_ptm_irq );
 
 	// Alphanumeric keyboard
 	DECLARE_READ8_MEMBER( ank_col_r );
@@ -644,6 +650,9 @@ private:
 	// Alphanumeric keyboard
 	int     m_ank_irqa;
 	int     m_ank_irqb;
+
+	// Master card (CMI-02)
+	int		m_cmi02_ptm_irq;
 };
 
 /**************************************
@@ -1639,7 +1648,7 @@ WRITE_LINE_MEMBER( cmi01a_device::cmi01a_1_ca2_w )
 
 WRITE_LINE_MEMBER( cmi01a_device::ch_int )
 {
-//  printf("CH%d INT: %x  %x\n", ch, state, m_int_state[0]);
+	//printf("CH%d INT: %x\n", m_channel, state);
 	dynamic_cast<cmi_state*>(owner())->set_interrupt(CPU_1, ch_int_levels[m_channel], state ? ASSERT_LINE : CLEAR_LINE);
 }
 
@@ -1819,7 +1828,7 @@ WRITE8_MEMBER( cmi01a_device::write )
 			int a1 = (m_ptm_output && BIT(offset, 3)) || (!BIT(offset, 3) && BIT(offset, 2));
 			int a2 = BIT(offset, 1);
 
-			//printf("CH%d PTM: [%x] %x\n", ch, (a2 << 2) | (a1 << 1) | a0, data);
+			//printf("CH%d PTM: [%x] %x, %d %d %d, %02x\n", m_channel, (a2 << 2) | (a1 << 1) | a0, data, a2, a1, a0, offset);
 			m_ptm->write(space, (a2 << 2) | (a1 << 1) | a0, data);
 			break;
 		}
@@ -1877,6 +1886,13 @@ WRITE8_MEMBER( cmi01a_device::cmi01a_ptm_c0 )
 	m_ptm_output = data;
 }
 
+WRITE_LINE_MEMBER( cmi_state::cmi02_ptm_irq )
+{
+	m_cmi02_ptm_irq = state;
+	set_interrupt(CPU_1, IRQ_TIMINT_LEVEL, m_cmi02_ptm_irq ? ASSERT_LINE : CLEAR_LINE);
+	//printf("CMI-02 PTM IRQ: %d\n", state);
+}
+
 READ8_MEMBER( cmi_state::cmi02_r )
 {
 	if (offset <= 0x1f)
@@ -1886,7 +1902,9 @@ READ8_MEMBER( cmi_state::cmi02_r )
 		for (int i = 0; i < 8; ++i)
 		{
 			if (ch_mask & (1 << i))
-				return m_channels[i]->read(space, i, offset & 0x1f);
+			{
+				return m_channels[i]->read(space, offset & 0x1f, 0xff);
+			}
 		}
 
 		return 0xff;
@@ -2509,6 +2527,7 @@ void cmi_state::machine_reset()
 	m_ank_irqa = 0;
 	m_ank_irqb = 0;
 	m_q133_acia_irq = 0;
+	m_cmi02_ptm_irq = 0;
 }
 
 void cmi_state::machine_start()
@@ -2636,6 +2655,7 @@ static MACHINE_CONFIG_START( cmi2x, cmi_state )
 
 	MCFG_DEVICE_ADD("cmi02_ptm", PTM6840, 0) // ptm_cmi02_config
 	MCFG_PTM6840_INTERNAL_CLOCK(2000000) // TODO
+	MCFG_PTM6840_IRQ_CB(WRITELINE(cmi_state, cmi02_ptm_irq))
 
 	MCFG_DEVICE_ADD("mkbd_acia_clock", CLOCK, 9600*16)
 	MCFG_CLOCK_SIGNAL_HANDLER(WRITELINE(cmi_state, mkbd_acia_clock))