diff --git a/src/devices/cpu/z80/nsc800.cpp b/src/devices/cpu/z80/nsc800.cpp
index bb5f47bb217..02d16e85f79 100644
--- a/src/devices/cpu/z80/nsc800.cpp
+++ b/src/devices/cpu/z80/nsc800.cpp
@@ -59,7 +59,6 @@ void nsc800_device::execute_set_input(int inputnum, int state)
 {
 	switch (inputnum)
 	{
-	case INPUT_LINE_IRQ0:
 	case NSC800_RSTA:
 		m_nsc800_irq_state[0] = state;
 		break;
diff --git a/src/devices/cpu/z80/z80.h b/src/devices/cpu/z80/z80.h
index 6822d81ea53..addab5979b5 100644
--- a/src/devices/cpu/z80/z80.h
+++ b/src/devices/cpu/z80/z80.h
@@ -10,7 +10,6 @@
 enum
 {
 	Z80_INPUT_LINE_WAIT = INPUT_LINE_IRQ0 + 1,
-	Z80_INPUT_LINE_BOGUSWAIT, // WAIT pin implementation used to be nonexistent, please remove this when all drivers are updated with Z80_INPUT_LINE_WAIT
 	Z80_INPUT_LINE_BUSRQ,
 
 	Z80_INPUT_LINE_MAX
diff --git a/src/mame/adc/super6.cpp b/src/mame/adc/super6.cpp
index b1b7bc96d06..6afe2d17f0d 100644
--- a/src/mame/adc/super6.cpp
+++ b/src/mame/adc/super6.cpp
@@ -2,20 +2,17 @@
 // copyright-holders:Curt Coder
 /*
 
-
-ToDo:
+TODO:
 - peripheral interfaces
 
 - Fix floppy. It needs to WAIT the cpu whenever port 0x14 is read, wait
   for either DRQ or INTRQ to assert, then release the cpu and then do the
-  actual port read. Our Z80 cannot do that.
+  actual port read. But it doesn't work properly at the moment. It gets stuck
+  if you load up the cpm disk (from software list). The other disks are useless.
+
   The schematic isn't clear, but it seems the 2 halves of U16 (as shown) have
   a common element, so that activity on one side can affect what happens on
   the other side.
-  If you uncomment the line in fdc_intrq_w, and change the BOGUSWAIT to WAIT
-  in fdc_r, then load up the cpm disk (from software list), it will read the
-  CP/M boot track into memory and attempt to run it. However, it has an issue
-  and returns to the monitor. The other disks are useless.
 
 */
 
@@ -201,7 +198,16 @@ uint8_t super6_state::fdc_r()
 
 	*/
 
-	m_maincpu->set_input_line(Z80_INPUT_LINE_BOGUSWAIT, ASSERT_LINE);
+	if (!machine().side_effects_disabled())
+	{
+		if (!m_z80_wait)
+		{
+			m_maincpu->set_input_line(Z80_INPUT_LINE_WAIT, ASSERT_LINE);
+			m_maincpu->defer_access();
+		}
+
+		m_z80_wait = !m_z80_wait;
+	}
 
 	return m_fdc->intrq_r() ? 0x7f : 0xff;
 }
@@ -384,7 +390,6 @@ void super6_state::fdc_intrq_w(int state)
 	if (state) m_maincpu->set_input_line(Z80_INPUT_LINE_WAIT, CLEAR_LINE);
 
 	m_ctc->trg3(state);   // J6 pin 7-8
-	// m_maincpu->set_state_int(Z80_AF, 0x7f00);   // hack, see notes
 }
 
 void super6_state::fdc_drq_w(int state)
@@ -420,6 +425,7 @@ void super6_state::fdc_drq_w(int state)
 void super6_state::machine_start()
 {
 	// state saving
+	save_item(NAME(m_z80_wait));
 	save_item(NAME(m_s100));
 	save_item(NAME(m_bank0));
 	save_item(NAME(m_bank1));
@@ -428,6 +434,7 @@ void super6_state::machine_start()
 
 void super6_state::machine_reset()
 {
+	m_z80_wait = false;
 	m_bank0 = m_bank1 = 0;
 
 	bankswitch();
diff --git a/src/mame/adc/super6.h b/src/mame/adc/super6.h
index db0cdb58019..78dc74d2b6a 100644
--- a/src/mame/adc/super6.h
+++ b/src/mame/adc/super6.h
@@ -80,6 +80,8 @@ private:
 	required_region_ptr<uint8_t> m_rom;
 	required_ioport m_j7;
 
+	bool m_z80_wait = false;
+
 	// memory state
 	uint8_t m_s100 = 0;
 	uint8_t m_bank0 = 0;
diff --git a/src/mame/enterprise/ep64.cpp b/src/mame/enterprise/ep64.cpp
index f9c9ccb07f6..46cc80829d4 100644
--- a/src/mame/enterprise/ep64.cpp
+++ b/src/mame/enterprise/ep64.cpp
@@ -608,7 +608,7 @@ void ep64_state::ep64(machine_config &config)
 	m_exp->set_io_space(m_dave, AS_IO);
 	m_exp->irq_wr().set_inputline(m_maincpu, INPUT_LINE_IRQ0);
 	m_exp->nmi_wr().set_inputline(m_maincpu, INPUT_LINE_NMI);
-	m_exp->wait_wr().set_inputline(m_maincpu, Z80_INPUT_LINE_BOGUSWAIT);
+	m_exp->wait_wr().set_inputline(m_maincpu, Z80_INPUT_LINE_WAIT);
 
 	CENTRONICS(config, m_centronics, centronics_devices, "printer");
 	m_centronics->busy_handler().set(FUNC(ep64_state::write_centronics_busy));
diff --git a/src/mame/morrow/mpz80.cpp b/src/mame/morrow/mpz80.cpp
index fef2ceab601..642f4326444 100644
--- a/src/mame/morrow/mpz80.cpp
+++ b/src/mame/morrow/mpz80.cpp
@@ -723,7 +723,7 @@ void mpz80_state::mpz80(machine_config &config)
 	S100_BUS(config, m_s100, XTAL(4'000'000) / 2);
 	m_s100->irq().set(FUNC(mpz80_state::s100_pint_w));
 	m_s100->nmi().set(FUNC(mpz80_state::s100_nmi_w));
-	m_s100->rdy().set_inputline(m_maincpu, Z80_INPUT_LINE_BOGUSWAIT);
+	m_s100->rdy().set_inputline(m_maincpu, Z80_INPUT_LINE_WAIT);
 	S100_SLOT(config, S100_TAG ":1", mpz80_s100_cards, "mm65k16s");
 	S100_SLOT(config, S100_TAG ":2", mpz80_s100_cards, "wunderbus");
 	S100_SLOT(config, S100_TAG ":3", mpz80_s100_cards, "dj2db");
diff --git a/src/mame/northstar/horizon.cpp b/src/mame/northstar/horizon.cpp
index d8397baa6c4..be99777a29c 100644
--- a/src/mame/northstar/horizon.cpp
+++ b/src/mame/northstar/horizon.cpp
@@ -213,7 +213,7 @@ void horizon_state::horizon(machine_config &config)
 
 	// S-100
 	S100_BUS(config, m_s100, XTAL(8'000'000) / 4);
-	m_s100->rdy().set_inputline(m_maincpu, Z80_INPUT_LINE_BOGUSWAIT);
+	m_s100->rdy().set_inputline(m_maincpu, Z80_INPUT_LINE_WAIT);
 	//S100_SLOT(config, S100_TAG":1", horizon_s100_cards, nullptr, nullptr); // CPU
 	S100_SLOT(config, "s100:2", horizon_s100_cards, nullptr); // RAM
 	S100_SLOT(config, "s100:3", horizon_s100_cards, "mdsad"); // MDS
diff --git a/src/mame/pinball/mrgame.cpp b/src/mame/pinball/mrgame.cpp
index 8efd90dd314..e7a29a866cd 100644
--- a/src/mame/pinball/mrgame.cpp
+++ b/src/mame/pinball/mrgame.cpp
@@ -728,7 +728,7 @@ void mrgame_state::mrgame(machine_config &config)
 	dacvol.add_route(0, "rdac", -1.0, DAC_INPUT_RANGE_LO);
 
 	tms5220_device &tms(TMS5220(config, "tms", 672000)); // uses a RC combination. 672k copied from jedi.h
-	tms.ready_cb().set_inputline("audiocpu2", Z80_INPUT_LINE_BOGUSWAIT);
+	tms.ready_cb().set_inputline("audiocpu2", Z80_INPUT_LINE_WAIT);
 	tms.add_route(ALL_OUTPUTS, "lspeaker", 1.0);
 	tms.add_route(ALL_OUTPUTS, "rspeaker", 1.0);
 
diff --git a/src/mame/skeleton/xor100.cpp b/src/mame/skeleton/xor100.cpp
index 709b4576de9..85a2b51233b 100644
--- a/src/mame/skeleton/xor100.cpp
+++ b/src/mame/skeleton/xor100.cpp
@@ -32,7 +32,7 @@ Note some of the commands are a bit buggy, eg F doesn't fill the last byte
 TODO:
 - Fix floppy. It needs to WAIT the cpu whenever port 0xFC is read, wait
   for either DRQ or INTRQ to assert, then release the cpu and then do the
-  actual port read. Our Z80 cannot do that.
+  actual port read.
 - The only available disks crash MAME when loaded.
 - honor jumper settings
 - CTC signal header
@@ -280,7 +280,7 @@ uint8_t xor100_state::fdc_wait_r()
 	{
 		if (!m_fdc_irq && !m_fdc_drq)
 		{
-			m_maincpu->set_input_line(Z80_INPUT_LINE_BOGUSWAIT, ASSERT_LINE);
+			//m_maincpu->set_input_line(Z80_INPUT_LINE_WAIT, ASSERT_LINE);
 		}
 	}
 
@@ -640,7 +640,7 @@ void xor100_state::xor100(machine_config &config)
 
 	// S-100
 	S100_BUS(config, m_s100, 8_MHz_XTAL / 4);
-	m_s100->rdy().set_inputline(m_maincpu, Z80_INPUT_LINE_BOGUSWAIT);
+	m_s100->rdy().set_inputline(m_maincpu, Z80_INPUT_LINE_WAIT);
 	S100_SLOT(config, S100_TAG ":1", xor100_s100_cards, nullptr);
 	S100_SLOT(config, S100_TAG ":2", xor100_s100_cards, nullptr);
 	S100_SLOT(config, S100_TAG ":3", xor100_s100_cards, nullptr);