diff --git a/src/mame/drivers/vt100.cpp b/src/mame/drivers/vt100.cpp
index 810587b7c46..3561394bfbe 100644
--- a/src/mame/drivers/vt100.cpp
+++ b/src/mame/drivers/vt100.cpp
@@ -424,7 +424,7 @@ static MACHINE_CONFIG_START( vt100, vt100_state )
 	MCFG_VT_VIDEO_RAM_CALLBACK(READ8(vt100_state, vt100_read_video_ram_r))
 	MCFG_VT_VIDEO_CLEAR_VIDEO_INTERRUPT_CALLBACK(WRITELINE(vt100_state, vt100_clear_video_interrupt))
 
-	MCFG_DEVICE_ADD("i8251", I8251, 0)
+	MCFG_DEVICE_ADD("i8251", I8251, 0) // 2.7648Mhz phi-clock (not used for tx clock or rx clock?)
 	MCFG_I8251_TXD_HANDLER(DEVWRITELINE(RS232_TAG, rs232_port_device, write_txd))
 	MCFG_I8251_DTR_HANDLER(DEVWRITELINE(RS232_TAG, rs232_port_device, write_dtr))
 	MCFG_I8251_RTS_HANDLER(DEVWRITELINE(RS232_TAG, rs232_port_device, write_rts))
@@ -433,7 +433,7 @@ static MACHINE_CONFIG_START( vt100, vt100_state )
 	MCFG_RS232_RXD_HANDLER(DEVWRITELINE("i8251", i8251_device, write_rxd))
 	MCFG_RS232_DSR_HANDLER(DEVWRITELINE("i8251", i8251_device, write_dsr))
 
-	MCFG_DEVICE_ADD(COM5016T_TAG, COM8116, XTAL_5_0688MHz)
+	MCFG_DEVICE_ADD(COM5016T_TAG, COM8116, XTAL_5_0688MHz/*XTAL_24_8832MHz / 9*/) // COM5016T-013, 2.7648Mhz Clock, currently hacked wrongly
 	MCFG_COM8116_FR_HANDLER(DEVWRITELINE("i8251", i8251_device, write_rxc))
 	MCFG_COM8116_FT_HANDLER(DEVWRITELINE("i8251", i8251_device, write_txc))
 
diff --git a/src/mame/machine/trs80.cpp b/src/mame/machine/trs80.cpp
index b2f706028e5..8c60a20d60a 100644
--- a/src/mame/machine/trs80.cpp
+++ b/src/mame/machine/trs80.cpp
@@ -420,7 +420,9 @@ WRITE8_MEMBER( trs80_state::trs80m4_e9_w )
     CCh    4800
     DDh    7200
     EEh    9600
-    FFh    19200 */
+    FFh    19200
+Note: this may be a COM5016 dual baud rate generator, or may be an equivalent circuit embedded in the gate array ASIC on the trs80 model 4
+	*/
 
 	static const int baud_clock[]={ 800, 1200, 1760, 2152, 2400, 4800, 9600, 19200, 28800, 32000, 38400, 57600, 76800, 115200, 153600, 307200 };
 	m_ay31015->set_receiver_clock(baud_clock[data & 0x0f]);