diff --git a/src/mame/sinclair/specnext_divmmc.cpp b/src/mame/sinclair/specnext_divmmc.cpp
new file mode 100644
index 0000000000000..c3741877bb567
--- /dev/null
+++ b/src/mame/sinclair/specnext_divmmc.cpp
@@ -0,0 +1,140 @@
+// license:BSD-3-Clause
+// copyright-holders:Andrei I. Holub
+/**********************************************************************
+    Spectrum Next DivMMC
+**********************************************************************/
+
+#include "emu.h"
+#include "specnext_divmmc.h"
+
+
+specnext_divmmc_device::specnext_divmmc_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
+	: device_t(mconfig, SPECNEXT_DIVMMC, tag, owner, clock)
+{
+}
+
+bool specnext_divmmc_device::conmem() const noexcept
+{
+	return BIT(m_divmmc_reg, 7);
+}
+
+bool specnext_divmmc_device::mapram() const noexcept
+{
+	return BIT(m_divmmc_reg, 6);
+}
+
+bool specnext_divmmc_device::page0() const noexcept
+{
+	return m_cpu_a_15_13 == 0;
+}
+
+bool specnext_divmmc_device::page1() const noexcept
+{
+	return m_cpu_a_15_13 == 1;
+}
+
+bool specnext_divmmc_device::rom_en() const noexcept
+{
+	return page0() && (conmem() || automap()) && !mapram();
+}
+
+bool specnext_divmmc_device::ram_en() const noexcept
+{
+	return (page0() && (conmem() || automap()) && mapram()) || (page1() && (conmem() || automap()));
+}
+
+u8 specnext_divmmc_device::ram_bank() const noexcept
+{
+	return page0() ? 3 : (m_divmmc_reg & 0x0f);
+}
+
+bool specnext_divmmc_device::automap_nmi_instant_on() const noexcept
+{
+	return m_automap_nmi_instant_on && m_button_nmi;
+}
+
+bool specnext_divmmc_device::automap_nmi_delayed_on() const noexcept
+{
+	return m_automap_nmi_delayed_on && m_button_nmi;
+}
+
+bool specnext_divmmc_device::automap() const noexcept
+{
+	return !m_automap_reset && (m_automap_held
+			|| (m_automap_active && (m_automap_instant_on || automap_nmi_instant_on()))
+			|| (m_automap_rom3_active && m_automap_rom3_instant_on));
+}
+
+void specnext_divmmc_device::clock_w() noexcept
+{
+	// Rising edge
+	if (m_automap_reset || m_retn_seen)
+		m_button_nmi = 0;
+	else if (m_divmmc_button)
+		m_button_nmi = 1;
+	else if (m_automap_held)
+		m_button_nmi = 0;
+
+	if (m_automap_reset || m_retn_seen)
+	{
+		m_automap_hold = 0;
+	}
+	else if (!m_cpu_mreq_n && !m_cpu_m1_n)
+	{
+		m_automap_hold = (m_automap_active && (m_automap_instant_on || m_automap_delayed_on || automap_nmi_instant_on() || automap_nmi_delayed_on()))
+				|| (m_automap_rom3_active && (m_automap_rom3_instant_on || m_automap_rom3_delayed_on))
+				|| (m_automap_held && !(m_automap_active && m_automap_delayed_off));
+	}
+
+	if (m_automap_reset || m_retn_seen)
+		m_automap_held = 0;
+	else if (m_cpu_mreq_n)
+		m_automap_held = m_automap_hold;
+}
+
+
+void specnext_divmmc_device::device_start()
+{
+	save_item(NAME(m_cpu_a_15_13));
+	save_item(NAME(m_cpu_mreq_n));
+	save_item(NAME(m_cpu_m1_n));
+	save_item(NAME(m_en));
+	save_item(NAME(m_automap_reset));
+	save_item(NAME(m_automap_active));
+	save_item(NAME(m_automap_rom3_active));
+	save_item(NAME(m_retn_seen));
+	save_item(NAME(m_divmmc_button));
+	save_item(NAME(m_divmmc_reg));
+	save_item(NAME(m_automap_instant_on));
+	save_item(NAME(m_automap_delayed_on));
+	save_item(NAME(m_automap_delayed_off));
+	save_item(NAME(m_automap_rom3_instant_on));
+	save_item(NAME(m_automap_rom3_delayed_on));
+	save_item(NAME(m_automap_nmi_instant_on));
+	save_item(NAME(m_automap_nmi_delayed_on));
+	save_item(NAME(m_button_nmi));
+	save_item(NAME(m_automap_hold));
+	save_item(NAME(m_automap_held));
+}
+
+void specnext_divmmc_device::device_reset()
+{
+	m_cpu_mreq_n = 0;
+	m_cpu_m1_n = 0;
+
+	m_automap_instant_on = 0;
+	m_automap_delayed_on = 0;
+	m_automap_delayed_off = 0;
+	m_automap_rom3_instant_on = 0;
+	m_automap_rom3_delayed_on = 0;
+	m_automap_nmi_instant_on = 0;
+	m_automap_nmi_delayed_on = 0;
+
+	m_automap_hold = 0;
+	m_automap_held = 0;
+	m_button_nmi = 0;
+}
+
+
+// device type definition
+DEFINE_DEVICE_TYPE(SPECNEXT_DIVMMC, specnext_divmmc_device, "specnext_divmmc", "Spectrum Next DivMMC")
diff --git a/src/mame/sinclair/specnext_divmmc.h b/src/mame/sinclair/specnext_divmmc.h
new file mode 100644
index 0000000000000..27d6023e18879
--- /dev/null
+++ b/src/mame/sinclair/specnext_divmmc.h
@@ -0,0 +1,89 @@
+// license:BSD-3-Clause
+// copyright-holders:Andrei I. Holub
+#ifndef MAME_SINCLAIR_SPECNEXT_DIVMMC_H
+#define MAME_SINCLAIR_SPECNEXT_DIVMMC_H
+
+#pragma once
+
+class specnext_divmmc_device : public device_t
+{
+public:
+	specnext_divmmc_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock);
+
+	void cpu_a_15_13_w(u8 data) { m_cpu_a_15_13 = data & 0x07; };
+	void cpu_mreq_n_w(bool data) { m_cpu_mreq_n = data; }
+	void cpu_m1_n_w(bool data) { m_cpu_m1_n = data; }
+	void automap_active_w(bool data) { m_automap_active = data; }
+	void automap_rom3_active_w(bool data) { m_automap_rom3_active = data; }
+
+	void en_w(bool data) { m_en = data; }
+	void automap_reset_w(bool data) { m_automap_reset = data; }
+	void retn_seen_w(bool data) { m_retn_seen = data; }
+
+	void divmmc_button_w(bool data) { m_divmmc_button = data; }
+	void divmmc_reg_w(u8 data) { m_divmmc_reg = data; }
+
+	void automap_instant_on_w(bool data) { m_automap_instant_on = data; }
+	void automap_delayed_on_w(bool data) { m_automap_delayed_on = data; }
+	void automap_delayed_off_w(bool data) { m_automap_delayed_off = data; }
+	void automap_rom3_instant_on_w(bool data) { m_automap_rom3_instant_on = data; }
+	void automap_rom3_delayed_on_w(bool data) { m_automap_rom3_delayed_on = data; }
+	void automap_nmi_instant_on_w(bool data) { m_automap_nmi_instant_on = data; }
+	void automap_nmi_delayed_on_w(bool data) { m_automap_nmi_delayed_on = data; }
+
+	bool divmmc_rom_en_r() const { return rom_en() && m_en; }
+	bool divmmc_ram_en_r() const { return ram_en() && m_en; }
+	bool divmmc_rdonly_r() const { return page0() || (mapram() && ram_bank() == 3); }
+	u8 divmmc_ram_bank_r() const { return ram_bank() & 0x0f; }
+
+	void clock_w() noexcept; // called on active clock edge
+
+protected:
+	virtual void device_start() override ATTR_COLD;
+	virtual void device_reset() override ATTR_COLD;
+
+private:
+	// in
+	u8 m_cpu_a_15_13;
+	bool m_cpu_mreq_n;
+	bool m_cpu_m1_n;
+
+	bool m_en;
+	bool m_automap_reset;
+	bool m_automap_active;
+	bool m_automap_rom3_active;
+	bool m_retn_seen;
+
+	bool m_divmmc_button;
+	u8 m_divmmc_reg;
+
+	bool m_automap_instant_on;
+	bool m_automap_delayed_on;
+	bool m_automap_delayed_off;
+	bool m_automap_rom3_instant_on;
+	bool m_automap_rom3_delayed_on;
+	bool m_automap_nmi_instant_on;
+	bool m_automap_nmi_delayed_on;
+
+	// internal
+	bool m_button_nmi;
+	bool m_automap_hold;
+	bool m_automap_held;
+
+	// signal
+	bool conmem() const noexcept;
+	bool mapram() const noexcept;
+	bool page0() const noexcept;
+	bool page1() const noexcept;
+	bool rom_en() const noexcept;
+	bool ram_en() const noexcept;
+	u8 ram_bank() const noexcept;
+	bool automap_nmi_instant_on() const noexcept;
+	bool automap_nmi_delayed_on() const noexcept;
+	bool automap() const noexcept;
+
+};
+
+DECLARE_DEVICE_TYPE(SPECNEXT_DIVMMC, specnext_divmmc_device)
+
+#endif // MAME_SINCLAIR_SPECNEXT_DIVMMC_H