Update uart.asm

Fixed some stuff in 16C2552 support
- Concurrent write was being enabled unintentionally
- Swapped the EPDSER UART base ports to match the boards annotations

Source/HBIOS/uart.asm

@@ -230,11 +230,23 @@ UART_INITDEV1:
 	LD	A,C
 	UART_OUTP(UART_DLL)		; SET DIVISOR (LS)
 ;
-	; SETUP FCR (DLAB MUST STILL BE ON FOR ACCESS TO BIT 5)
-	LD	A,%00100111		; FIFO ENABLE & RESET, 64 BYTE FIFO ENABLE ON 750+
+	; FOR 750+, WE ENABLE THE 64-BYTE FIFO
+	; DLAB MUST STILL BE ON FOR ACCESS TO BIT 5
+	; WE DO *NOT* ENABLE ANY OTHER FCR BITS HERE
+	; BEACAUSE IT WILL SCREW UP THE 2552!!!
+	LD	A,%00100000
 	UART_OUTP(UART_FCR)		; DO IT
 ;
-	; SETUP LCR FROM SECOND CONFIG BYTE (DLAB IS CLEARED)
+	XOR	A			; DLAB OFF NOW
+	UART_OUTP(UART_LCR)		; DO IT
+;
+	; SETUP FCR, BIT 5 IS KEPT ON EVEN THOUGH IT IS PROBABLY
+	; IRRELEVANT BECAUSE IT ONLY APPLIES TO 750 AND DLAB IS
+	; NOW OFF, BUT DOESN'T HURT.
+	LD	A,%00100111		; FIFO ENABLE & RESET
+	UART_OUTP(UART_FCR)		; DO IT
+;
+	; SETUP LCR FROM SECOND CONFIG BYTE
 	LD	A,(IY + 4)		; GET CONFIG BYTE
 	AND	~$C0			; ISOLATE PARITY, STOP/DATA BITS
 	UART_OUTP(UART_LCR)		; SAVE IT
@@ -364,8 +376,9 @@ UART_DETECT:
 	CP	$5A			; SPR STILL THERE?
 	JR	NZ,UART_DETECT1		; NOPE, HIDDEN, MUST BE 16650/850
 ;
-	; RESET LCR TO DEFAULT
-	LD	A,$80			; DLAB BIT ON
+	; RESET LCR TO DEFAULT (DLAB OFF)
+	;LD	A,$80			; DLAB BIT ON
+	XOR	A			; DLAB BIT OFF
 	UART_OUTP(UART_LCR)		; RESET LCR
 ;
 	; TEST FCR TO ISOLATE 16450/550/550A
@@ -381,6 +394,9 @@ UART_DETECT:
 	JR	UART_DETECT_16750	; ONLY THING LEFT IS 16750
 ;
 UART_DETECT1:	; PICK BETWEEN 16650/850
+	; RESET LCR TO DEFAULT (DLAB OFF)
+	XOR	A			; DLAB BIT OFF
+	UART_OUTP(UART_LCR)		; RESET LCR
 	; NOT SURE HOW TO DIFFERENTIATE 16650 FROM 16850 YET
 	JR	UART_DETECT_16650	; ASSUME 16650
 	RET
@@ -630,15 +646,15 @@ UART_CFG:
 	; UARTRC SERIAL PORT A
 	.DB	0				; DEVICE NUMBER (UPDATED DURING INIT)
 	.DB	0				; UART TYPE
-	.DB	$A0				; IO PORT BASE (RBR, THR)
-	.DB	$A0 + UART_LSR			; LINE STATUS PORT (LSR)
+	.DB	$A8				; IO PORT BASE (RBR, THR)
+	.DB	$A8 + UART_LSR			; LINE STATUS PORT (LSR)
 	.DW	UARTCFG				; LINE CONFIGURATION
 	.FILL	2,$FF				; FILLER
 	; UARTRC SERIAL PORT B
 	.DB	0				; DEVICE NUMBER (UPDATED DURING INIT)
 	.DB	0				; UART TYPE
-	.DB	$A8				; IO PORT BASE (RBR, THR)
-	.DB	$A8 + UART_LSR			; LINE STATUS PORT (LSR)
+	.DB	$A0				; IO PORT BASE (RBR, THR)
+	.DB	$A0 + UART_LSR			; LINE STATUS PORT (LSR)
 	.DW	UARTCFG				; LINE CONFIGURATION
 	.FILL	2,$FF				; FILLER
 #ENDIF