diff --git a/src/mame/drivers/mbee.cpp b/src/mame/drivers/mbee.cpp
index 7b2153e249b..baaf4d4a4cb 100644
--- a/src/mame/drivers/mbee.cpp
+++ b/src/mame/drivers/mbee.cpp
@@ -241,11 +241,10 @@ void mbee_state::mbeepc_io(address_map &map)
 	map(0x0000, 0x0003).mirror(0xff10).rw(m_pio, FUNC(z80pio_device::read_alt), FUNC(z80pio_device::write_alt));
 	map(0x0008, 0x0008).mirror(0xff10).rw(FUNC(mbee_state::port08_r), FUNC(mbee_state::port08_w));
 	map(0x0009, 0x0009).mirror(0xff00).nopw();
+	map(0x000a, 0x000a).select(0xff10).rw(FUNC(mbee_state::telcom_r), FUNC(mbee_state::port0a_w));
 	map(0x000b, 0x000b).mirror(0xff10).w(FUNC(mbee_state::port0b_w));
 	map(0x000c, 0x000c).mirror(0xff10).r(m_crtc, FUNC(mc6845_device::status_r)).w(FUNC(mbee_state::m6545_index_w));
 	map(0x000d, 0x000d).mirror(0xff10).r(m_crtc, FUNC(mc6845_device::register_r)).w(FUNC(mbee_state::m6545_data_w));
-	map(0x000a, 0x000a).mirror(0xfe10).rw(FUNC(mbee_state::telcom_low_r), FUNC(mbee_state::port0a_w));
-	map(0x010a, 0x010a).mirror(0xfe10).rw(FUNC(mbee_state::telcom_high_r), FUNC(mbee_state::port0a_w));
 }
 
 void mbee_state::mbeeppc_io(address_map &map)
@@ -254,12 +253,11 @@ void mbee_state::mbeeppc_io(address_map &map)
 	map(0x0000, 0x0003).mirror(0xff10).rw(m_pio, FUNC(z80pio_device::read_alt), FUNC(z80pio_device::write_alt));
 	map(0x0008, 0x0008).mirror(0xff10).rw(FUNC(mbee_state::port08_r), FUNC(mbee_state::port08_w));
 	map(0x0009, 0x0009).mirror(0xff00).nopw();
+	map(0x000a, 0x000a).select(0xff10).rw(FUNC(mbee_state::telcom_r), FUNC(mbee_state::port0a_w));
 	map(0x000b, 0x000b).mirror(0xff10).w(FUNC(mbee_state::port0b_w));
 	map(0x000c, 0x000c).mirror(0xff00).r(m_crtc, FUNC(mc6845_device::status_r)).w(FUNC(mbee_state::m6545_index_w));
 	map(0x000d, 0x000d).mirror(0xff10).r(m_crtc, FUNC(mc6845_device::register_r)).w(FUNC(mbee_state::m6545_data_w));
 	map(0x001c, 0x001c).mirror(0xff00).rw(FUNC(mbee_state::port1c_r), FUNC(mbee_state::port1c_w));
-	map(0x000a, 0x000a).mirror(0xfe10).rw(FUNC(mbee_state::telcom_low_r), FUNC(mbee_state::port0a_w));
-	map(0x010a, 0x010a).mirror(0xfe10).rw(FUNC(mbee_state::telcom_high_r), FUNC(mbee_state::port0a_w));
 }
 
 void mbee_state::mbeett_io(address_map &map)
@@ -270,15 +268,13 @@ void mbee_state::mbeett_io(address_map &map)
 	map(0x0006, 0x0006).mirror(0xff00).w(FUNC(mbee_state::port06_w));
 	map(0x0007, 0x0007).mirror(0xff00).r(FUNC(mbee_state::port07_r));
 	map(0x0008, 0x0008).mirror(0xff00).rw(FUNC(mbee_state::port08_r), FUNC(mbee_state::port08_w));
+	map(0x000a, 0x000a).select(0xff10).rw(FUNC(mbee_state::telcom_r), FUNC(mbee_state::port0a_w));
 	map(0x000b, 0x000b).mirror(0xff00).w(FUNC(mbee_state::port0b_w));
 	map(0x000c, 0x000c).mirror(0xff00).r(m_crtc, FUNC(mc6845_device::status_r)).w(FUNC(mbee_state::m6545_index_w));
 	map(0x000d, 0x000d).mirror(0xff00).r(m_crtc, FUNC(mc6845_device::register_r)).w(FUNC(mbee_state::m6545_data_w));
 	map(0x0018, 0x001b).mirror(0xff00).r(FUNC(mbee_state::port18_r));
 	map(0x001c, 0x001f).mirror(0xff00).rw(FUNC(mbee_state::port1c_r), FUNC(mbee_state::port1c_w));
-	map(0x0009, 0x0009).mirror(0xfe00).r(FUNC(mbee_state::speed_low_r));
-	map(0x0109, 0x0109).mirror(0xfe00).r(FUNC(mbee_state::speed_high_r));
-	map(0x000a, 0x000a).mirror(0xfe00).rw(FUNC(mbee_state::telcom_low_r), FUNC(mbee_state::port0a_w));
-	map(0x010a, 0x010a).mirror(0xfe00).rw(FUNC(mbee_state::telcom_high_r), FUNC(mbee_state::port0a_w));
+	map(0x0009, 0x0009).select(0xff00).r(FUNC(mbee_state::speed_r));
 	map(0x0068, 0x006f).mirror(0xff00).noprw();    // swallow i/o to SCC which was never fitted to production machines
 }
 
@@ -323,8 +319,7 @@ void mbee_state::mbee256_io(address_map &map)
 	map(0x0006, 0x0006).mirror(0xff00).w(FUNC(mbee_state::port06_w));
 	map(0x0007, 0x0007).mirror(0xff00).r(FUNC(mbee_state::port07_r));
 	map(0x0008, 0x0008).mirror(0xff00).rw(FUNC(mbee_state::port08_r), FUNC(mbee_state::port08_w));
-	map(0x0009, 0x0009).mirror(0xfd00).r(FUNC(mbee_state::speed_low_r));
-	map(0x0209, 0x0209).mirror(0xfd00).r(FUNC(mbee_state::speed_high_r));
+	map(0x0009, 0x0009).select(0xff00).r(FUNC(mbee_state::speed_r));
 	map(0x0009, 0x0009).mirror(0xff00).nopw();
 	map(0x000b, 0x000b).mirror(0xff00).w(FUNC(mbee_state::port0b_w));
 	map(0x000c, 0x000c).mirror(0xff00).r(m_crtc, FUNC(mc6845_device::status_r)).w(FUNC(mbee_state::m6545_index_w));
diff --git a/src/mame/includes/mbee.h b/src/mame/includes/mbee.h
index 91f11882d41..3c6de28bf36 100644
--- a/src/mame/includes/mbee.h
+++ b/src/mame/includes/mbee.h
@@ -100,10 +100,8 @@ private:
 	u8 port1c_r();
 	void port1c_w(u8 data);
 	void port50_w(u8 data);
-	u8 telcom_low_r();
-	u8 telcom_high_r();
-	u8 speed_low_r();
-	u8 speed_high_r();
+	u8 telcom_r(offs_t);
+	u8 speed_r(offs_t);
 	void m6545_index_w(u8 data);
 	void m6545_data_w(u8 data);
 	u8 video_low_r(offs_t offset);
diff --git a/src/mame/machine/mbee.cpp b/src/mame/machine/mbee.cpp
index 6daefa6fbb9..5e541956e68 100644
--- a/src/mame/machine/mbee.cpp
+++ b/src/mame/machine/mbee.cpp
@@ -202,19 +202,12 @@ u8 mbee_state::port18_r()
 
 ************************************************************/
 
-u8 mbee_state::speed_low_r()
+u8 mbee_state::speed_r(offs_t offset)
 {
-	m_maincpu->set_unscaled_clock(3375000);
+	m_maincpu->set_unscaled_clock(BIT(offset, 8, 2) ? 6750000 : 3375000);
 	return 0xff;
 }
 
-u8 mbee_state::speed_high_r()
-{
-	m_maincpu->set_unscaled_clock(6750000);
-	return 0xff;
-}
-
-
 
 /***********************************************************
 
@@ -388,20 +381,12 @@ void mbee_state::port0a_w(u8 data)
 	m_0a = data & 15;
 }
 
-u8 mbee_state::telcom_low_r()
+// Banking of Telcom rom
+// Todo: implement 4 banks, however no roms use it.
+u8 mbee_state::telcom_r(offs_t offset)
 {
-/* Read of port 0A - set Telcom rom to first half */
 	if (m_telcom)
-		m_telcom->set_entry(0);
-
-	return m_0a;
-}
-
-u8 mbee_state::telcom_high_r()
-{
-/* Read of port 10A - set Telcom rom to 2nd half */
-	if (m_telcom)
-		m_telcom->set_entry(1);
+		m_telcom->set_entry(BIT(offset, 8));
 
 	return m_0a;
 }