diff --git a/src/mame/drivers/excali64.cpp b/src/mame/drivers/excali64.cpp
index 51626c0bc56..ec881b12608 100644
--- a/src/mame/drivers/excali64.cpp
+++ b/src/mame/drivers/excali64.cpp
@@ -280,11 +280,12 @@ WRITE8_MEMBER( excali64_state::porte4_w )
 
 /*
 d0 = precomp (selectable by jumper)
-d1 = size select (we only support 13cm)
+d1 = size select
 d2 = density select (0 = double)
 */
 WRITE8_MEMBER( excali64_state::portec_w )
 {
+	m_fdc->enmf_w(BIT(data, 1));
 	m_fdc->dden_w(BIT(data, 2));
 }
 
@@ -603,7 +604,7 @@ void excali64_state::excali64(machine_config &config)
 	CASSETTE(config, m_cass);
 	m_cass->add_route(ALL_OUTPUTS, "mono", 0.05);
 
-	WD2793(config, m_fdc, 16_MHz_XTAL / 16);
+	WD2793(config, m_fdc, 16_MHz_XTAL / 8);
 	m_fdc->drq_wr_callback().set(m_dma, FUNC(z80dma_device::rdy_w));
 	FLOPPY_CONNECTOR(config, "fdc:0", excali64_floppies, "525qd", excali64_state::floppy_formats).enable_sound(true);
 	FLOPPY_CONNECTOR(config, "fdc:1", excali64_floppies, "525qd", excali64_state::floppy_formats).enable_sound(true);
diff --git a/src/mame/drivers/super6.cpp b/src/mame/drivers/super6.cpp
index 3226df0480d..ebc6161cffd 100644
--- a/src/mame/drivers/super6.cpp
+++ b/src/mame/drivers/super6.cpp
@@ -247,7 +247,7 @@ WRITE8_MEMBER( super6_state::fdc_w )
 	m_fdc->dden_w(!BIT(data, 3));
 
 	// disk size
-	m_fdc->set_unscaled_clock (BIT(data, 4) ? 1'000'000 : 2'000'000);  // division occurs inside fdc depending on ENMF
+	m_fdc->enmf_w(!BIT(data, 4));
 }