UART Driver Interrupt Driven Receive

- The UART driver has been enhanced to allow use of interrupt driven receive buffer and RTS flow control.  It will only be used if enabled and the chip detected has no auto-flow control capability.

Source/Apps/XM/xmhb.180

@@ -112,11 +112,22 @@ MINIT_HB1:
 	RST	08		; Do it, D=device type
 	LD	A,D		; Put result in A
 	CP	00H		; UART?
-	JP	Z,UA_INIT	; If so, do UART H/W init
+	JP	Z,MINIT_HB2	; If so, do UART H/W init
 	CP	80H		; USB-FIFO?
 	JP	Z,UF_INIT	; If so, do USB-FIFO H/W init
 	JP	HB_INIT		; Otherwise, use BIOS I/O
 ;
+MINIT_HB2:
+	; Handle UART driver special.  If receive interrupts active,
+	; we must use BIOS I/O.  Otherwise, direct UART I/O is best
+	LD	B,06H		; Serial device function
+	LD	A,(UNIT)	; Get xfer unit
+	LD	C,A		; Put in C
+	RST	08		; Do it, H = UART TYPE
+	BIT	7,H		; Check for interrupt driven receive
+	JP	Z,UA_INIT	; If not, do direct UART I/O
+	JP	HB_INIT		; else use BIOS I/O
+;
 MINIT_UB:
 	; Display UNA notification string
 	LD	DE,UB_TAG	; BIOS notification string