diff --git a/scripts/src/bus.lua b/scripts/src/bus.lua
index 4892fd8b9b1..90e2a936c18 100644
--- a/scripts/src/bus.lua
+++ b/scripts/src/bus.lua
@@ -4108,6 +4108,8 @@ end
 ---------------------------------------------------
 if (BUSES["EPSON_QX"]~=null) then
 	files {
+		MAME_DIR .. "src/devices/bus/epson_qx/cqgmem.cpp",
+		MAME_DIR .. "src/devices/bus/epson_qx/cqgmem.h",
 		MAME_DIR .. "src/devices/bus/epson_qx/cr1510.cpp",
 		MAME_DIR .. "src/devices/bus/epson_qx/cr1510.h",
 		MAME_DIR .. "src/devices/bus/epson_qx/ide.cpp",
diff --git a/src/devices/bus/epson_qx/cqgmem.cpp b/src/devices/bus/epson_qx/cqgmem.cpp
new file mode 100644
index 00000000000..822e1ed516d
--- /dev/null
+++ b/src/devices/bus/epson_qx/cqgmem.cpp
@@ -0,0 +1,134 @@
+// license:BSD-3-Clause
+// copyright-holders:Brian Johnson
+/*******************************************************************
+ *
+ * commodity quote graphics 1 megabyte memory expansion
+ *
+ *******************************************************************/
+
+#include "emu.h"
+#include "cqgmem.h"
+
+//**************************************************************************
+//  CQGMEM DEVICE
+//**************************************************************************
+
+DEFINE_DEVICE_TYPE(EPSON_QX_OPTION_CQGMEM, bus::epson_qx::cqgmem_device, "option_cqgmem", "Epson QX-10 1MB Memory Expansion")
+
+namespace bus::epson_qx {
+
+static INPUT_PORTS_START( cqgmem )
+	PORT_START("IOBASE")
+	PORT_CONFNAME(0xf0, 0xf0, "IO Base Address Selection")
+	PORT_CONFSETTING(0x80, "&80")
+	PORT_CONFSETTING(0x90, "&90")
+	PORT_CONFSETTING(0xa0, "&A0")
+	PORT_CONFSETTING(0xb0, "&B0")
+	PORT_CONFSETTING(0xc0, "&C0")
+	PORT_CONFSETTING(0xd0, "&D0")
+	PORT_CONFSETTING(0xe0, "&E0")
+	PORT_CONFSETTING(0xf0, "&F0")
+INPUT_PORTS_END
+
+//-------------------------------------------------
+//  cqgmem_device - constructor
+//-------------------------------------------------
+cqgmem_device::cqgmem_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) :
+	device_t(mconfig, EPSON_QX_OPTION_CQGMEM, tag, owner, clock),
+	device_option_expansion_interface(mconfig, *this),
+	device_memory_interface(mconfig, *this),
+	m_ram(*this, "xmem", 0x100000, ENDIANNESS_LITTLE),
+	m_banks(*this, "bank%u", 0U),
+	m_iobase(*this, "IOBASE"),
+	m_space_config("xmem", ENDIANNESS_LITTLE, 8, 20, 0, address_map_constructor(FUNC(cqgmem_device::xmem_map), this)),
+	m_installed(false)
+{
+}
+
+//-------------------------------------------------
+//  device_input_ports - device-specific ports
+//-------------------------------------------------
+ioport_constructor cqgmem_device::device_input_ports() const
+{
+	return INPUT_PORTS_NAME( cqgmem );
+}
+
+//-------------------------------------------------
+//  device_start - device-specific startup
+//-------------------------------------------------
+void cqgmem_device::device_start()
+{
+	m_installed = false;
+
+	save_item(NAME(m_installed));
+	save_item(NAME(m_banks_enabled));
+}
+
+//-------------------------------------------------
+//  device_reset - device-specific reset
+//-------------------------------------------------
+void cqgmem_device::device_reset()
+{
+	if (!m_installed) {
+		address_space &space = m_bus->iospace();
+		offs_t iobase = m_iobase->read() & 0xf0;
+		space.install_device(iobase, iobase+0x07, *this, &cqgmem_device::io_map);
+
+		for (int i = 0; i < m_banks.size(); ++i) {
+			m_banks[i]->configure_entries(0, 128, m_ram, 0x2000);
+		}
+	}
+
+	m_banks_enabled = 0;
+
+	for (int i = 0; i < m_banks.size(); ++i) {
+		m_banks[i]->set_entry(0);
+	}
+}
+
+//  memory_space_config - return a description of
+//  any address spaces owned by this device
+//-------------------------------------------------
+
+device_memory_interface::space_config_vector cqgmem_device::memory_space_config() const
+{
+	return space_config_vector {
+		std::make_pair(0, &m_space_config)
+	};
+}
+
+void cqgmem_device::xmem_map(address_map &map)
+{
+	map(0x00000, 0xfffff).ram().share("xmem");
+}
+
+void cqgmem_device::write(offs_t offset, uint8_t data)
+{
+	memory_view::memory_view_entry &view = m_bus->memview();
+
+	uint8_t bank = offset & 0x07;
+	uint8_t page = data & 0x7f;
+	uint8_t enable = (m_banks_enabled & ~((data & 0x80) >> bank)) |  ((data & 0x80) >> bank);
+	uint16_t bank_addr = bank * 0x2000;
+
+	m_banks[bank]->set_entry(page);
+
+	if (data & 0x80) {
+		if (enable != m_banks_enabled) {
+			view.unmap_readwrite(bank_addr, bank_addr + 0x1fff);
+			view.install_readwrite_bank(bank_addr, bank_addr + 0x1fff, m_banks[bank]);
+		}
+	} else {
+		if (enable != m_banks_enabled) {
+			view.unmap_readwrite(bank_addr, bank_addr + 0x1fff);
+		}
+	}
+	m_banks_enabled = enable;
+}
+
+void cqgmem_device::io_map(address_map &map)
+{
+	map(0x00, 0x06).w(FUNC(cqgmem_device::write));
+}
+
+} // namespace bus::epson_qx
diff --git a/src/devices/bus/epson_qx/cqgmem.h b/src/devices/bus/epson_qx/cqgmem.h
new file mode 100644
index 00000000000..ba019059c3e
--- /dev/null
+++ b/src/devices/bus/epson_qx/cqgmem.h
@@ -0,0 +1,61 @@
+// license:BSD-3-Clause
+// copyright-holders:Brian Johnson
+/*******************************************************************
+ *
+ * commodity quote graphics 1 megabyte memory expansion
+ *
+ *******************************************************************/
+
+#ifndef MAME_BUS_EPSON_QX_CQGMEM_H
+#define MAME_BUS_EPSON_QX_CQGMEM_H
+
+#pragma once
+
+#include "option.h"
+
+namespace bus::epson_qx {
+
+//**************************************************************************
+//  TYPE DEFINITIONS
+//**************************************************************************
+
+/* commodity quote graphics 1M memory expansion */
+
+class cqgmem_device : public device_t, public device_option_expansion_interface, public device_memory_interface
+{
+public:
+	// construction/destruction
+	cqgmem_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
+
+protected:
+	// device-level overrides
+	virtual void device_start() override;
+	virtual void device_reset() override;
+
+	// optional information overrides
+	virtual ioport_constructor device_input_ports() const override;
+	virtual space_config_vector memory_space_config() const override;
+
+	void write(offs_t offset, uint8_t data);
+
+	void io_map(address_map &map);
+	void xmem_map(address_map &map);
+
+private:
+	uint8_t m_banks_enabled;
+
+	memory_share_creator<uint8_t> m_ram;
+	memory_bank_array_creator<7> m_banks;
+	required_ioport m_iobase;
+	const address_space_config m_space_config;
+
+	bool m_installed;
+};
+
+} // namespace bus::epson_qx
+
+// device type definition
+DECLARE_DEVICE_TYPE_NS(EPSON_QX_OPTION_CQGMEM, bus::epson_qx, cqgmem_device)
+
+
+#endif // MAME_BUS_EPSON_QX_CQGMEM_H
diff --git a/src/devices/bus/epson_qx/option.cpp b/src/devices/bus/epson_qx/option.cpp
index 5b6ad3a0f3e..620570e2b22 100644
--- a/src/devices/bus/epson_qx/option.cpp
+++ b/src/devices/bus/epson_qx/option.cpp
@@ -8,6 +8,7 @@
 #include "emu.h"
 #include "option.h"
 
+#include "cqgmem.h"
 #include "cr1510.h"
 #include "ide.h"
 #include "multifont.h"
@@ -210,6 +211,7 @@ void device_option_expansion_interface::interface_pre_start()
 
 void option_bus_devices(device_slot_interface &device)
 {
+	device.option_add("cqgmem", EPSON_QX_OPTION_CQGMEM);
 	device.option_add("cr1510", EPSON_QX_OPTION_CR1510);
 	device.option_add("ide", EPSON_QX_OPTION_IDE);
 	device.option_add("multifont", EPSON_QX_OPTION_MULTIFONT);