diff --git a/src/mess/machine/c1551.c b/src/mess/machine/c1551.c
index 5e9fa13a7af..00d83145fab 100644
--- a/src/mess/machine/c1551.c
+++ b/src/mess/machine/c1551.c
@@ -11,13 +11,11 @@
 
     TODO:
 
-	- paddle expansion port passthru
     - byte latching does not match hardware behavior
       (CPU skips data bytes if implemented per schematics)
 
 */
 
-#include "c1541.h"
 #include "c1551.h"
 
 
@@ -32,6 +30,7 @@
 #define C64H156_TAG		"u6"
 #define PLA_TAG			"u1"
 
+
 enum
 {
 	LED_POWER = 0,
@@ -367,6 +366,39 @@ static C64H156_INTERFACE( ga_intf )
 };
 
 
+//-------------------------------------------------
+//  PLUS4_EXPANSION_INTERFACE( expansion_intf )
+//-------------------------------------------------
+
+READ8_MEMBER( c1551_device::exp_dma_r )
+{
+	return m_slot->dma_cd_r(offset);
+}
+
+WRITE8_MEMBER( c1551_device::exp_dma_w )
+{
+	m_slot->dma_cd_w(offset, data);
+}
+
+WRITE_LINE_MEMBER( c1551_device::exp_irq_w )
+{
+	m_slot->irq_w(state);
+}
+
+WRITE_LINE_MEMBER( c1551_device::exp_aec_w )
+{
+	m_slot->aec_w(state);
+}
+
+static PLUS4_EXPANSION_INTERFACE( expansion_intf )
+{
+	DEVCB_DEVICE_MEMBER(DEVICE_SELF_OWNER, c1551_device, exp_dma_r),
+	DEVCB_DEVICE_MEMBER(DEVICE_SELF_OWNER, c1551_device, exp_dma_w),
+	DEVCB_DEVICE_LINE_MEMBER(DEVICE_SELF_OWNER, c1551_device, exp_irq_w),
+	DEVCB_DEVICE_LINE_MEMBER(DEVICE_SELF_OWNER, c1551_device, exp_aec_w)
+};
+
+
 //-------------------------------------------------
 //  MACHINE_DRIVER( c1551 )
 //-------------------------------------------------
@@ -383,6 +415,8 @@ static MACHINE_CONFIG_FRAGMENT( c1551 )
 
 	MCFG_LEGACY_FLOPPY_DRIVE_ADD(FLOPPY_0, c1541_floppy_interface)
 	MCFG_64H156_ADD(C64H156_TAG, XTAL_16MHz, ga_intf)
+
+	MCFG_PLUS4_EXPANSION_SLOT_ADD(PLUS4_EXPANSION_SLOT_TAG, 0, expansion_intf, plus4_expansion_cards, NULL, NULL)
 MACHINE_CONFIG_END
 
 
@@ -437,6 +471,7 @@ c1551_device::c1551_device(const machine_config &mconfig, const char *tag, devic
 	  m_ga(*this, C64H156_TAG),
 	  m_pla(*this, PLA_TAG),
 	  m_image(*this, FLOPPY_0),
+	  m_exp(*this, PLUS4_EXPANSION_SLOT_TAG),
 	  m_tcbm_data(0xff),
 	  m_status(1),
 	  m_dav(1),
@@ -465,6 +500,7 @@ void c1551_device::device_start()
 	save_item(NAME(m_status));
 	save_item(NAME(m_dav));
 	save_item(NAME(m_ack));
+	save_item(NAME(m_dev));
 }
 
 
@@ -537,7 +573,7 @@ bool c1551_device::tpi1_selected(offs_t offset)
 
 UINT8 c1551_device::plus4_cd_r(address_space &space, offs_t offset, int ba, int cs0, int c1l, int c2l, int cs1, int c1h, int c2h)
 {
-	UINT8 data = 0;
+	UINT8 data = m_exp->cd_r(space, offset, ba, cs0, c1l, c2l, cs1, c1h, c2h);
 
 	if (tpi1_selected(offset))
 	{
@@ -558,6 +594,18 @@ void c1551_device::plus4_cd_w(address_space &space, offs_t offset, UINT8 data, i
 	{
 		tpi6525_w(m_tpi1, offset & 0x07, data);
 	}
+
+	m_exp->cd_w(space, offset, data, ba, cs0, c1l, c2l, cs1, c1h, c2h);
+}
+
+
+//-------------------------------------------------
+//  plus4_screen_update - screen update
+//-------------------------------------------------
+
+UINT32 c1551_device::plus4_screen_update(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
+{
+	return m_exp->screen_update(screen, bitmap, cliprect);
 }
 
 
@@ -571,6 +619,8 @@ void c1551_device::plus4_breset_w(int state)
 	{
 		device_reset();
 	}
+
+	m_exp->breset_w(state);
 }
 
 
diff --git a/src/mess/machine/c1551.h b/src/mess/machine/c1551.h
index 67adb7e6580..12bade8cbff 100644
--- a/src/mess/machine/c1551.h
+++ b/src/mess/machine/c1551.h
@@ -20,6 +20,8 @@
 #include "formats/g64_dsk.h"
 #include "machine/64h156.h"
 #include "machine/6525tpi.h"
+#include "machine/c1541.h"
+#include "machine/cbmipt.h"
 #include "machine/pls100.h"
 #include "machine/plus4exp.h"
 
@@ -48,18 +50,25 @@ public:
 
 	DECLARE_READ8_MEMBER( port_r );
 	DECLARE_WRITE8_MEMBER( port_w );
+
 	DECLARE_READ8_MEMBER( tcbm_data_r );
 	DECLARE_WRITE8_MEMBER( tcbm_data_w );
 	DECLARE_READ8_MEMBER( yb_r );
 	DECLARE_WRITE8_MEMBER( yb_w );
 	DECLARE_READ8_MEMBER( tpi0_pc_r );
 	DECLARE_WRITE8_MEMBER( tpi0_pc_w );
+
 	DECLARE_READ8_MEMBER( tpi1_pa_r );
 	DECLARE_WRITE8_MEMBER( tpi1_pa_w );
 	DECLARE_READ8_MEMBER( tpi1_pb_r );
 	DECLARE_READ8_MEMBER( tpi1_pc_r );
 	DECLARE_WRITE8_MEMBER( tpi1_pc_w );
 
+	DECLARE_READ8_MEMBER( exp_dma_r );
+	DECLARE_WRITE8_MEMBER( exp_dma_w );
+	DECLARE_WRITE_LINE_MEMBER( exp_irq_w );
+	DECLARE_WRITE_LINE_MEMBER( exp_aec_w );
+
 protected:
     // device-level overrides
     virtual void device_config_complete() { m_shortname = "c1551"; }
@@ -70,6 +79,7 @@ protected:
     // device_plus4_expansion_card_interface overrides
 	virtual UINT8 plus4_cd_r(address_space &space, offs_t offset, int ba, int cs0, int c1l, int c2l, int cs1, int c1h, int c2h);
 	virtual void plus4_cd_w(address_space &space, offs_t offset, UINT8 data, int ba, int cs0, int c1l, int c2l, int cs1, int c1h, int c2h);
+	virtual UINT32 plus4_screen_update(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect);
 	virtual void plus4_breset_w(int state);
 
 private:
@@ -81,6 +91,7 @@ private:
 	required_device<c64h156_device> m_ga;
 	required_device<pls100_device> m_pla;
 	required_device<legacy_floppy_image_device> m_image;
+	required_device<plus4_expansion_slot_device> m_exp;
 
 	// TCBM bus
 	UINT8 m_tcbm_data;						// data