hd6301: fix timer 2 serial clock

src/devices/cpu/m6800/m6801.cpp

@@ -2084,14 +2084,12 @@ void hd6301x_cpu_device::increment_t2cnt(int amount)
 
 		if (BIT(m_rmcr, 5) && !m_use_ext_serclock)
 		{
-			if (m_ext_serclock + amount >= 32)
+			m_ext_serclock++;
+			if (m_ext_serclock >= 32)
 			{
-				m_ext_serclock = (m_ext_serclock + amount) % 32;
-				serial_transmit();
-				serial_receive();
+				m_ext_serclock = 0;
+				machine().scheduler().synchronize(timer_expired_delegate(FUNC(hd6301x_cpu_device::sci_tick), this));
 			}
-			else
-				m_ext_serclock += amount;
 		}
 
 		m_tcsr3 |= 0x80;

src/mame/novag/snova.cpp

@@ -11,7 +11,6 @@ NVRAM won't work properly (supremo doesn't have NVRAM).
 
 TODO:
 - if/when MAME supports an exit callback, hook up nsnova power-off switch to that
-- serial port isn't working, same problem as nsvip
 - unmapped reads from 0x33/0x34 (nsnova) or 0x3c/0x3d (supremo)
 - supremo unmapped writes to 0x2000/0x6000, always 0?
 - is "Aquamarine / Super Nova" the same rom as nsnova and just a redesign?

src/mame/novag/svip.cpp

@@ -26,8 +26,7 @@ The LCD is the same as the one in Primo / Supremo / Super Nova.
 
 TODO:
 - if/when MAME supports an exit callback, hook up power-off switch to that
-- serial port isn't working, MCU emulation problem? (it has nothing to do with
-  the distributor box, that's just a dumb expander)
+- serial port isn't working for nsvip V1.x? it only sends empty chars
 - unmapped reads from 0x3* range, same as snova driver
 - is (non-super) VIP on the same hardware? minus EPROM or RS232
 
@@ -138,7 +137,7 @@ u8 svip_state::p2_r()
 		if (m_inp_mux & m_inputs[i]->read())
 			data |= 0x20 << i;
 
-	return ~data;
+	return ~data ^ 8;
 }
 
 void svip_state::p2_w(u8 data)

src/mame/saitek/turbo16k.cpp

@@ -23,7 +23,7 @@ TODO:
   and says "Sixteen Level Computerized Chess"
 
 Hardware notes:
-- HD6301Y0 MCU, 8MHz or 12MHz (LC osc, no XTAL)
+- Hitachi HD6301Y0P/F MCU, 8MHz or 12MHz (LC osc, no XTAL)
 - 16 board LEDs (can be tri-color), 7 or 8 status LEDs
 - buttons sensor board, piezo