diff --git a/src/mame/drivers/model1.cpp b/src/mame/drivers/model1.cpp
index 411311e8692..772732ad2c3 100644
--- a/src/mame/drivers/model1.cpp
+++ b/src/mame/drivers/model1.cpp
@@ -784,11 +784,24 @@ READ16_MEMBER(model1_state::network_ctl_r)
 	if(offset)
 		return 0x40;
 	else
-		return 0x00;
+		return m_io_command;
 }
 
 WRITE16_MEMBER(model1_state::network_ctl_w)
 {
+	if (offset == 0)
+	{
+		m_io_command = data & 0xff;
+
+		// totally made up; proper emulation of I/O board needed
+		// (command 3 is EEPROM write, so should take a lot longer)
+		m_io_timer->adjust(data == 3 ? attotime::from_msec(100) : attotime::from_usec(10));
+	}
+}
+
+TIMER_DEVICE_CALLBACK_MEMBER(model1_state::io_command_acknowledge)
+{
+	m_io_command = 0;
 }
 
 WRITE16_MEMBER(model1_state::md1_w)
@@ -1605,6 +1618,7 @@ static MACHINE_CONFIG_START( model1 )
 	MCFG_CPU_IRQ_ACKNOWLEDGE_DRIVER(model1_state,irq_callback)
 
 	MCFG_TIMER_DRIVER_ADD_SCANLINE("scantimer", model1_state, model1_interrupt, "screen", 0, 1)
+	MCFG_TIMER_DRIVER_ADD("iotimer", model1_state, io_command_acknowledge)
 
 	MCFG_MACHINE_START_OVERRIDE(model1_state,model1)
 	MCFG_MACHINE_RESET_OVERRIDE(model1_state,model1)
@@ -1654,7 +1668,9 @@ static MACHINE_CONFIG_START( model1_vr )
 	MCFG_CPU_PROGRAM_MAP(model1_vr_mem)
 	MCFG_CPU_IO_MAP(model1_vr_io)
 	MCFG_CPU_IRQ_ACKNOWLEDGE_DRIVER(model1_state,irq_callback)
+
 	MCFG_TIMER_DRIVER_ADD_SCANLINE("scantimer", model1_state, model1_interrupt, "screen", 0, 1)
+	MCFG_TIMER_DRIVER_ADD("iotimer", model1_state, io_command_acknowledge)
 
 	MCFG_CPU_ADD("tgp", MB86233, 16000000)
 	MCFG_CPU_PROGRAM_MAP(model1_vr_tgp_map)
diff --git a/src/mame/includes/model1.h b/src/mame/includes/model1.h
index 0c5fa94cb12..c4e4d10f86a 100644
--- a/src/mame/includes/model1.h
+++ b/src/mame/includes/model1.h
@@ -38,6 +38,7 @@ public:
 		, m_dsbz80(*this, DSBZ80_TAG)
 		, m_tgp(*this, "tgp")
 		, m_screen(*this, "screen")
+		, m_io_timer(*this, "iotimer")
 		, m_mr2(*this, "mr2")
 		, m_mr(*this, "mr")
 		, m_display_list0(*this, "display_list0")
@@ -58,6 +59,7 @@ public:
 
 	DECLARE_READ16_MEMBER(network_ctl_r);
 	DECLARE_WRITE16_MEMBER(network_ctl_w);
+	TIMER_DEVICE_CALLBACK_MEMBER(io_command_acknowledge);
 
 	DECLARE_READ16_MEMBER(io_r);
 	DECLARE_WRITE16_MEMBER(io_w);
@@ -188,6 +190,8 @@ private:
 	bool m_dump;
 	bool m_swa;
 
+	uint8_t m_io_command;
+
 	// Devices
 	required_device<v60_device> m_maincpu;          // V60
 	required_device<segam1audio_device> m_m1audio;  // Model 1 standard sound board
@@ -196,6 +200,7 @@ private:
 	optional_device<dsbz80_device> m_dsbz80;        // Digital Sound Board
 	optional_device<mb86233_cpu_device> m_tgp;
 	required_device<screen_device> m_screen;
+	required_device<timer_device> m_io_timer;
 
 	required_shared_ptr<uint16_t> m_mr2;
 	required_shared_ptr<uint16_t> m_mr;
diff --git a/src/mame/machine/model1.cpp b/src/mame/machine/model1.cpp
index f763ab83701..57be8288de5 100644
--- a/src/mame/machine/model1.cpp
+++ b/src/mame/machine/model1.cpp
@@ -1942,6 +1942,7 @@ WRITE16_MEMBER(model1_state::model1_tgp_copro_ram_w)
 MACHINE_START_MEMBER(model1_state,model1)
 {
 	m_ram_data = std::make_unique<uint32_t[]>(0x10000);
+	m_io_command = 0;
 
 	save_pointer(NAME(m_ram_data.get()), 0x10000);
 	save_item(NAME(m_ram_adr));
@@ -1959,6 +1960,7 @@ MACHINE_START_MEMBER(model1_state,model1)
 	save_item(NAME(m_mat_stack_pos));
 	save_item(NAME(m_acc));
 	save_item(NAME(m_list_length));
+	save_item(NAME(m_io_command));
 }
 
 void model1_state::tgp_reset(bool swa)