diff --git a/src/mess/machine/sns_slot.c b/src/mess/machine/sns_slot.c
index 61d65403f1b..433d5ac7d7a 100644
--- a/src/mess/machine/sns_slot.c
+++ b/src/mess/machine/sns_slot.c
@@ -671,6 +671,11 @@ bool base_sns_cart_slot_device::call_load()
 		if (software_entry() == NULL)
 			setup_addon_from_fullpath();
 
+		// in carts with an add-on CPU having internal dump, this speeds up access to the internal rom
+		// by installing read_bank in address space and mapping m_bios there
+		m_cart->speedup_addon_bios_access();
+
+
 		setup_nvram();
 
 		if (m_cart->get_nvram_size() || m_cart->get_rtc_ram_size())
diff --git a/src/mess/machine/sns_slot.h b/src/mess/machine/sns_slot.h
index 51f2aa708d0..ad76d1d4ced 100644
--- a/src/mess/machine/sns_slot.h
+++ b/src/mess/machine/sns_slot.h
@@ -115,6 +115,7 @@ public:
 	virtual DECLARE_WRITE8_MEMBER(write_ram) { UINT32 mask = m_nvram_size - 1; m_nvram[offset & mask] = data; return; } // NVRAM access
 	virtual DECLARE_READ8_MEMBER(chip_read) { return 0xff; }
 	virtual DECLARE_WRITE8_MEMBER(chip_write) {}
+	virtual void speedup_addon_bios_access() {};
 
 	void rom_alloc(running_machine &machine, UINT32 size);
 	void nvram_alloc(running_machine &machine, UINT32 size);
diff --git a/src/mess/machine/sns_upd.c b/src/mess/machine/sns_upd.c
index f78a5ade6fc..52f4bb52dfa 100644
--- a/src/mess/machine/sns_upd.c
+++ b/src/mess/machine/sns_upd.c
@@ -76,17 +76,22 @@ sns_rom_seta11dsp_device::sns_rom_seta11dsp_device(const machine_config &mconfig
 
 void sns_rom20_necdsp_device::device_start()
 {
+	m_dsp_prg = auto_alloc_array(machine(), UINT32, 0x2000/4);
+	m_dsp_data = auto_alloc_array(machine(), UINT16, 0x800/2);
 }
 
 void sns_rom21_necdsp_device::device_start()
 {
+	m_dsp_prg = auto_alloc_array(machine(), UINT32, 0x2000/4);
+	m_dsp_data = auto_alloc_array(machine(), UINT16, 0x800/2);
 }
 
 void sns_rom_setadsp_device::device_start()
 {
+	m_dsp_prg = auto_alloc_array(machine(), UINT32, 0x10000/4);
+	m_dsp_data = auto_alloc_array(machine(), UINT16, 0x1000/2);
 }
 
-
 /*-------------------------------------------------
  mapper specific handlers
  -------------------------------------------------*/
@@ -348,6 +353,48 @@ machine_config_constructor sns_rom_seta11dsp_device::device_mconfig_additions()
 }
 
 
+// To make faster DSP access to its internal rom, let's install read banks and map m_bios there with correct byte order
+
+void sns_rom20_necdsp_device::speedup_addon_bios_access()
+{
+	m_upd7725->space(AS_PROGRAM).install_read_bank(0x0000, 0x07ff, "dsp_prg");
+	m_upd7725->space(AS_DATA).install_read_bank(0x0000, 0x03ff, "dsp_data");
+	membank("dsp_prg")->set_base(m_dsp_prg);
+	membank("dsp_data")->set_base(m_dsp_data);
+	// copy data in the correct format
+	for (int x = 0; x < 0x800; x++)
+		m_dsp_prg[x] = (m_bios[x * 4] << 24) | (m_bios[x * 4 + 1] << 16) | (m_bios[x * 4 + 2] << 8) | 0x00;
+	for (int x = 0; x < 0x400; x++)
+		m_dsp_data[x] = (m_bios[0x2000 + x * 2] << 8) | m_bios[0x2000 + x * 2 + 1];
+}
+
+void sns_rom21_necdsp_device::speedup_addon_bios_access()
+{
+	m_upd7725->space(AS_PROGRAM).install_read_bank(0x0000, 0x07ff, "dsp_prg");
+	m_upd7725->space(AS_DATA).install_read_bank(0x0000, 0x03ff, "dsp_data");
+	membank("dsp_prg")->set_base(m_dsp_prg);
+	membank("dsp_data")->set_base(m_dsp_data);
+	// copy data in the correct format
+	for (int x = 0; x < 0x800; x++)
+		m_dsp_prg[x] = (m_bios[x * 4] << 24) | (m_bios[x * 4 + 1] << 16) | (m_bios[x * 4 + 2] << 8) | 0x00;
+	for (int x = 0; x < 0x400; x++)
+		m_dsp_data[x] = (m_bios[0x2000 + x * 2] << 8) | m_bios[0x2000 + x * 2 + 1];
+}
+
+void sns_rom_setadsp_device::speedup_addon_bios_access()
+{
+	m_upd96050->space(AS_PROGRAM).install_read_bank(0x0000, 0x3fff, "dsp_prg");
+	m_upd96050->space(AS_DATA).install_read_bank(0x0000, 0x07ff, "dsp_data");
+	membank("dsp_prg")->set_base(m_dsp_prg);
+	membank("dsp_data")->set_base(m_dsp_data);
+	// copy data in the correct format
+	for (int x = 0; x < 0x3fff; x++)
+		m_dsp_prg[x] = (m_bios[x * 4] << 24) | (m_bios[x * 4 + 1] << 16) | (m_bios[x * 4 + 2] << 8) | 0x00;
+	for (int x = 0; x < 0x07ff; x++)
+		m_dsp_data[x] = (m_bios[0x10000 + x * 2] << 8) | m_bios[0x10000 + x * 2 + 1];
+}
+
+
 
 
 // Legacy versions including DSP dump roms, in order to support faulty dumps missing DSP data...
diff --git a/src/mess/machine/sns_upd.h b/src/mess/machine/sns_upd.h
index f937aa0a10c..245f1e82505 100644
--- a/src/mess/machine/sns_upd.h
+++ b/src/mess/machine/sns_upd.h
@@ -19,6 +19,7 @@ public:
 	virtual void device_start();
 	virtual void device_config_complete() { m_shortname = "sns_rom_necdsp"; }
 	virtual machine_config_constructor device_mconfig_additions() const;
+	virtual void speedup_addon_bios_access();
 
 	required_device<upd7725_device> m_upd7725;
 
@@ -28,6 +29,9 @@ public:
 
 	virtual DECLARE_READ32_MEMBER(necdsp_prg_r);
 	virtual DECLARE_READ16_MEMBER(necdsp_data_r);
+	
+	UINT32 *m_dsp_prg;
+	UINT16 *m_dsp_data;
 };
 
 // ======================> sns_rom21_necdsp_device
@@ -43,6 +47,7 @@ public:
 	virtual void device_start();
 	virtual void device_config_complete() { m_shortname = "sns_rom21_necdsp"; }
 	virtual machine_config_constructor device_mconfig_additions() const;
+	virtual void speedup_addon_bios_access();
 
 	required_device<upd7725_device> m_upd7725;
 
@@ -52,6 +57,9 @@ public:
 
 	virtual DECLARE_READ32_MEMBER(necdsp_prg_r);
 	virtual DECLARE_READ16_MEMBER(necdsp_data_r);
+
+	UINT32 *m_dsp_prg;
+	UINT16 *m_dsp_data;
 };
 
 // ======================> sns_rom_setadsp_device
@@ -65,6 +73,7 @@ public:
 	// device-level overrides
 	virtual void device_start();
 	virtual void device_config_complete() { m_shortname = "sns_rom_setadsp"; }
+	virtual void speedup_addon_bios_access();
 
 	required_device<upd96050_device> m_upd96050;
 
@@ -74,6 +83,9 @@ public:
 
 	virtual DECLARE_READ32_MEMBER(setadsp_prg_r);
 	virtual DECLARE_READ16_MEMBER(setadsp_data_r);
+	
+	UINT32 *m_dsp_prg;
+	UINT16 *m_dsp_data;
 };
 
 // ======================> sns_rom_seta10dsp_device