SIO Driver Interrupt Based Receive

Source/Apps/XM/xmdm125.asm

@@ -328,7 +328,7 @@ MAXMIN	EQU	60	; Minutes for maximum file transfer time.
 ; Length of external patch program.  If over 128 bytes, get/set size
 ;
 LARGEIO	EQU	YES	; Yes, if modem patch area over 128 bytes
-LARSIZE	EQU	180H	; If 'LARGEIO' set patch area size (bytes) here
+LARSIZE	EQU	500H	; If 'LARGEIO' set patch area size (bytes) here
 ;
 ;=======================================================================
 ;

Source/Apps/XM/xmhb.180

@@ -67,95 +67,182 @@ MINIT:
 	LD	C,9		; BDOS string display function
 	CALL	BDOS		; Do it
 ;
-	; Get system type
-	LD	DE,00202H	; D := 2, E := 2
-	MLT	DE		; DE := D * E == 4
-	BIT	2,E		; Bit 2 wil be set if mlt happend
-	LD	HL,U_JPTBL	; Assume Z80 (UART)
-	LD	DE,UART		; UART port notification string
-	JR	Z,MINIT2	; Yes, Z80, do vector copy
-	LD	HL,A_JPTBL	; Otherwise Z180 (ASCI)
-	LD	DE,ASCI		; ASCI port notification string
+	; Identify BIOS (RomWBW HBIOS or UNA UBIOS)
+	CALL	IDBIO		; 1=HBIOS, 2=UBIOS
+	LD	(BIOID),A	; Save it
+	DEC	A		; Test for HBIOS
+	JR	Z,HINIT		; Do HBIOS setup
+	DEC	A		; Test for UBIOS
+	JR	Z,UINIT		; Do UBIOS setup
 ;
-MINIT2:
-	; Display port notification string
-	PUSH	HL		; Save HL
-	LD	C,9		; BDOS string display function
-	CALL	BDOS		; Do it
-	POP	HL		; Recover HL
-;
-	; Copy real vectors into active jump table
-	LD	DE,JPTBL	; Real jump table is destination
-	LD	BC,7 * 3	; Copy 7 3-byte entries
-	LDIR			; Do the copy
-;
-	; Check for UNA (UBIOS)
-	LD	A,(0FFFDH)	; fixed location of UNA API vector
-	CP	0C3H		; jp instruction?
-	JR	NZ,MINIT3	; if not, not UNA
-	LD	HL,(0FFFEH)	; get jp address
-	LD	A,(HL)		; get byte at target address
-	CP	0FDH		; first byte of UNA push ix instruction
-	JR	NZ,MINIT3	; if not, not UNA
-	INC	HL		; point to next byte
-	LD	A,(HL)		; get next byte
-	CP	0E5H		; second byte of UNA push ix instruction
-	JR	NZ,MINIT3	; if not, not UNA
-;
-	; Display UNA notification string
-	LD	DE,UBIOS	; BIOS notification string
-	LD	C,9		; BDOS string display function
-	CALL	BDOS
-;
-	; Get CPU speed from UNA and return
-	LD	C,0F8H		; UNA BIOS Get PHI function
-	RST	08		; Returns speed in Hz in DE:HL
-	LD	B,4		; Divide MHz in DE:HL by 100000H 
-MINIT2A:
-	SRL	D		; ... to get approx CPU speed in
-	RR	E		; ...MHz.  Throw away HL, and
-	DJNZ	MINIT2A		; ...right shift DE by 4.
-	INC	E		; Fix up for value truncation
-	LD	A,E		; Put in A
-	RET			; Done
-;
-MINIT3:
-	; Not UNA, try RomwBW HBIOS for CPU speed lookup
-	LD	HL,(0FFFEH)	; HL := HBIOS ident location
-	LD	A,'W'		; First byte of ident
-	CP	(HL)		; Compare
-	JR	NZ,MINIT4	; Not HBIOS
-	INC	HL		; Next byte of ident
-	LD	A,~'W'		; Second byte of ident
-	CP	(HL)		; Compare
-	JR	NZ,MINIT4	; Not HBIOS
-;
-	; Display RomWBW notification string
-	LD	DE,HBIOS	; BIOS notification string
-	LD	C,9		; BDOS string display function
-	CALL	BDOS		; Do it
-;
-	; Get CPU speed from RomWBW HBIOS and return
-	LD	B,0F8H		; HBIOS SYSGET function 0xF8
-	LD	C,0F0H		; CPUINFO subfunction 0xF0
-	RST	08		; Do it, L := CPU speed in MHz
-	LD	A,L		; Move it to A
-	RET			; Done
-;
-MINIT4:
 	; Neither UNA nor RomWBW
 	LD	DE,BIOERR	; BIOS error message
 	LD	C,9		; BDOS string display function
 	CALL	BDOS		; Do it
 	JP	0		; Bail out!
 ;
-RBC	DB	"RBC, 28-Aug-2017, $"
+HINIT:
 ;
-UART	DB	"UART0$"
-ASCI	DB	"ASCI0$"
+	; Display RomWBW notification string
+	LD	DE,HBIOS	; BIOS notification string
+	LD	C,9		; BDOS string display function
+	CALL	BDOS		; Do it
 ;
-UBIOS	DB	" [UNA]", 13, 10, "$"
-HBIOS	DB	" [WBW]", 13, 10, "$"
+	; Get platform id from RomWBW HBIOS and save it
+	LD	B,0F1H		; HBIOS VER function 0xF1
+	LD	C,0		; Required reserved value
+	RST	08		; Do it, L := Platform ID
+	LD	A,L		; Move to A
+	LD	(PLTID),A	; Save it
+;
+	; Get CPU speed from RomWBW HBIOS and save it
+	LD	B,0F8H		; HBIOS SYSGET function 0xF8
+	LD	C,0F0H		; CPUINFO subfunction 0xF0
+	RST	08		; Do it, L := CPU speed in MHz
+	LD	A,L		; Move it to A
+	LD	(CPUSPD),A	; Save it
+	JR	MINIT1		; Continue general initialization
+;
+UINIT:
+;
+	; Display UNA notification string
+	LD	DE,UBIOS	; BIOS notification string
+	LD	C,9		; BDOS string display function
+	CALL	BDOS		; Do it
+;
+	; Get CPU speed from UNA and save it
+	LD	C,0F8H		; UNA BIOS Get PHI function
+	RST	08		; Returns speed in Hz in DE:HL
+	LD	B,4		; Divide MHz in DE:HL by 100000H 
+UINIT1:
+	SRL	D		; ... to get approx CPU speed in
+	RR	E		; ...MHz.  Throw away HL, and
+	DJNZ	UINIT1		; ...right shift DE by 4.
+	INC	E		; Fix up for value truncation
+	LD	A,E		; Put in A
+	LD	(CPUSPD),A	; Save it
+	JR	MINIT1		; Continue general initialization
+;
+MINIT1:
+	; NOTE: PLTID is only set if RomWBW HBIOS is active.  This is OK
+	; because RC2014 is only support by RomWBW HBIOS at this point.
+	LD	A,(PLTID)	; Get the platform id
+	CP	7		; Check for RC2014
+	JR	Z,RCINIT	; Handle RC2014 special
+;
+	; Check for Z180 which implies ASCI serial port
+	LD	DE,00202H	; D := 2, E := 2
+	MLT	DE		; DE := D * E == 4
+	BIT	2,E		; Bit 2 wil be set if mlt happend
+	JR	Z,MINIT2	; Not Z180 (ASCI), look for others
+	LD	HL,ASCI_JPTBL	; Point to Z180 (ASCI) jump table
+	LD	DE,ASCI		; ASCI port notification string
+	JR	MINIT3		; Complete the initialization
+;
+MINIT2:
+	; Not a Z180, so assume RBC standard UART serial port
+	LD	HL,UART_JPTBL	; Assume Z80 (UART)
+	LD	DE,UART		; UART port notification string
+	JR	MINIT3		; Complete the initialization
+;
+RCINIT:
+	; Check for SIO/2 serial port
+	LD	C,080H		; SIO command port
+	XOR	A		; RD0
+	OUT	(C),A		; Access RD0
+	IN	A,(C)		; Get RD0 value
+	LD	B,A		; Save it
+	LD	A,1		; RD1
+	OUT	(C),A		; Access RD1
+	IN	A,(C)		; Get RD1 value
+	CP	B		; Compare
+	JR	Z,RCINIT1	; If equal, no SIO port there
+	LD	HL,SIO_JPTBL	; SIO jump table address
+	LD	DE,SIO		; SIO port notification string
+	JR	MINIT3		; Complete the initialization
+;
+RCINIT1:
+	; Assume RC2014 ACIA port
+	LD	HL,ACIA_JPTBL	; ACIA jump table address
+	LD	DE,ACIA		; ACIA port notification string
+	JR	MINIT3		; Complete the initialization
+;
+MINIT3:
+	PUSH	HL		; Save HL
+
+	; Display port notification string
+	LD	C,9		; BDOS string display function
+	CALL	BDOS		; Do it
+;
+	; Newline
+	LD	C,9		; BDOS string display function
+	LD	DE,CRLF		; Newline
+	CALL	BDOS		; Do it
+;
+	; Copy real vectors into active jump table
+	POP	HL		; Recover HL
+	LD	DE,JPTBL	; Real jump table is destination
+	LD	BC,7 * 3	; Copy 7 3-byte entries
+	LDIR			; Do the copy
+;
+	; Return with CPU speed in A
+	LD	A,(CPUSPD)	; Get CPU speed saved above
+	RET			; and return
+;
+; Identify active BIOS.  RomWBW HBIOS=1, UNA UBIOS=2, else 0
+;
+IDBIO:
+;
+	; Check for UNA (UBIOS)
+	LD	A,(0FFFDH)	; fixed location of UNA API vector
+	CP	0C3H		; jp instruction?
+	JR	NZ,IDBIO1	; if not, not UNA
+	LD	HL,(0FFFEH)	; get jp address
+	LD	A,(HL)		; get byte at target address
+	CP	0FDH		; first byte of UNA push ix instruction
+	JR	NZ,IDBIO1	; if not, not UNA
+	INC	HL		; point to next byte
+	LD	A,(HL)		; get next byte
+	CP	0E5H		; second byte of UNA push ix instruction
+	JR	NZ,IDBIO1	; if not, not UNA, check others
+	LD	A,2		; UNA BIOS id = 2
+	RET			; and done
+;
+IDBIO1:
+	; Check for RomWBW (HBIOS)
+	LD	HL,(0FFFEH)	; HL := HBIOS ident location
+	LD	A,'W'		; First byte of ident
+	CP	(HL)		; Compare
+	JR	NZ,IDBIO2	; Not HBIOS
+	INC	HL		; Next byte of ident
+	LD	A,~'W'		; Second byte of ident
+	CP	(HL)		; Compare
+	JR	NZ,IDBIO2	; Not HBIOS
+	LD	A,1		; HBIOS BIOS id = 1
+	RET			; and done
+;
+IDBIO2:
+	; No idea what this is
+	XOR	A		; Setup return value of 0
+	RET			; and done
+;
+;
+;
+BIOID	DB	0		; BIOS ID, 1=HBIOS, 2=UBIOS
+PLTID	DB	0		; Platform ID
+CPUSPD	DB	0		; CPU speed in MHz
+;
+RBC	DB	"RBC, 06-Nov-2017$"
+;
+UART	DB	", UART0$"
+ASCI	DB	", ASCI0$"
+SIO	DB	", SIO0$"
+ACIA	DB	", ACIA0$"
+;
+UBIOS	DB	" [UNA]$"
+HBIOS	DB	" [WBW]$"
+;
+CRLF	DB	13, 10, "$"
 ;
 BIOERR	DB	13, 10, 13, 10, "*** Unknown BIOS ***", 13, 10, "$"
 ;
@@ -211,7 +298,7 @@ U_FRME	EQU	08H		; bit for framing error
 ; table at program startup.  See MINIT above.  Note that only a
 ; subset of the jump table is overlaid (SENDR to SPEED).
 ;
-U_JPTBL:
+UART_JPTBL:
 	JP	U_SENDR		; send character (via pop psw)
 	JP	U_CAROK		; test for carrier
 	JP	U_MDIN		; receive data byte
@@ -325,7 +412,7 @@ A_FRME	EQU	10H		;Z180 STAT:FE - framing error bit
 ; table at program startup.  See MINIT above.  Note that only a
 ; subset of the jump table is overlaid (SENDR to SPEED).
 ;
-A_JPTBL:
+ASCI_JPTBL:
 	JP	A_SENDR		;send character (via pop psw)
 	JP	A_CAROK		;test for carrier
 	JP	A_MDIN		;receive data byte
@@ -408,5 +495,148 @@ A_SNDRDY:
 A_SPEED:
 	LD	A,8		; arbitrarily return 9600 baud
 	RET
+;
+;=======================================================================
+;=======================================================================
+;
+; RC2014 SIO/2
+;
+;=======================================================================
+;=======================================================================
+;
+; SIO port constants
+;
+S_CMD	EQU	80H		; SIO Command port
+S_DAT	EQU	81H		; SIO Data port
+;
+; Following jump table is dynamically patched over initial jump
+; table at program startup.  See MINIT above.  Note that only a
+; subset of the jump table is overlaid (SENDR to SPEED).
+;
+SIO_JPTBL:
+	JP	S_SENDR		;send character (via pop psw)
+	JP	S_CAROK		;test for carrier
+	JP	S_MDIN		;receive data byte
+	JP	S_GETCHR	;get character from modem
+	JP	S_RCVRDY	;check receive ready
+	JP	S_SNDRDY	;check send ready
+	JP	S_SPEED		;get speed value for file transfer time
+;
+;-----------------------------------------------------------------------
+;
+; Send character on top of stack
+;
+S_SENDR:
+	POP	AF		; get character to send from stack
+	OUT	(S_DAT),A	; send to port
+	RET
+;
+;-----------------------------------------------------------------------
+;
+; Test and rep;ort carrier status, Z set if carrier present
+;
+S_CAROK:
+	XOR	A		; not used, always indicate present
+	RET
+;
+;-----------------------------------------------------------------------
+;
+; Get a character (assume character ready has already been tested)
+;
+S_MDIN:
+S_GETCHR:
+	IN	A,(S_DAT)	; read character from port
+	RET
+;
+;-----------------------------------------------------------------------
+;
+; Test for character ready to receive, Z = ready
+; Error code returned in A register
+; *** Error code does not seem to be used ***
+;
+S_RCVRDY:
+	XOR	A		; A := 0
+	OUT	(S_CMD),A	; Access RD0
+	IN	A,(S_CMD)	; Get RD0
+	AND	00000001B	; Isolate rx ready bit
+	CP	00000001B	; ZF = rx ready
+;
+	 IF ERRDET
+;
+	; With error detection (slower)
+	PUSH	BC		; save BC
+	PUSH	AF		; save AF
+	LD	A,1		; A := 1
+	OUT	(S_CMD),A	; Access RD1
+	IN	A,(S_CMD)	; Get RD1
+	AND	01110000B	; isolate line err bits
+	POP	AF		; restore AF
+	LD	A,B		; err bits (B) to A
+	POP	BC		; restore BC
+;
+	 ELSE
+;
+	; No error detection (faster)
+	LD	A,0		; report no line errors
+;
+	 ENDIF
+;
+	RET
+;
+;-----------------------------------------------------------------------
+;
+; Test for ready to send a character, Z = ready
+;
+S_SNDRDY:
+	XOR	A		; A := 0
+	OUT	(S_CMD),A	; Access RD0
+	IN	A,(S_CMD)	; Get RD0
+	AND	00000100B	; Isolate tx empty bit
+	CP	00000100B	; ZF = tx empty
+	RET
+;
+;-----------------------------------------------------------------------
+;
+; Report baud rate (index into SPTBL returned in regsiter A)
+;
+S_SPEED:
+	LD	A,8		; arbitrarily return 9600 baud
+	RET
+;
+;=======================================================================
+;=======================================================================
+;
+; RC2014 ACIA
+;
+;=======================================================================
+;=======================================================================
+;
+; ACIA port constants
+;
+C_CMD	EQU	80H		; SIO Command port
+C_DAT	EQU	81H		; SIO Data port
+;
+; Following jump table is dynamically patched over initial jump
+; table at program startup.  See MINIT above.  Note that only a
+; subset of the jump table is overlaid (SENDR to SPEED).
+;
+ACIA_JPTBL:
+	JP	C_SENDR		;send character (via pop psw)
+	JP	C_CAROK		;test for carrier
+	JP	C_MDIN		;receive data byte
+	JP	C_GETCHR	;get character from modem
+	JP	C_RCVRDY	;check receive ready
+	JP	C_SNDRDY	;check send ready
+	JP	C_SPEED		;get speed value for file transfer time
+;
+C_SENDR:
+C_CAROK:
+C_MDIN:
+C_GETCHR:
+C_RCVRDY:
+C_SNDRDY:
+C_SPEED:
+	; Not yet implemeted...
+	JP	0
 ;
 	END

Source/HBIOS/cfg_rc.asm

@@ -8,7 +8,7 @@
 CPUOSC		.EQU	7372800		; CPU OSC FREQ
 RAMSIZE		.EQU	512		; SIZE OF RAM IN KB, MUST MATCH YOUR HARDWARE!!!
 DEFSERCFG	.EQU	SER_115200_8N1	; DEFAULT SERIAL LINE CONFIG (SHOULD MATCH ABOVE)
-INTTYPE		.EQU	IT_NONE		; INTERRUPT HANDLING TYPE (IT_NONE, IT_SIMH, IT_Z180, IT_CTC, ...)
+INTTYPE		.EQU	IT_RC		; INTERRUPT HANDLING TYPE (IT_NONE, IT_SIMH, IT_Z180, IT_CTC, ...)
 ;
 CRTACT		.EQU	FALSE		; CRT ACTIVATION AT STARTUP
 VDAEMU		.EQU	EMUTYP_ANSI	; DEFAULT VDA EMULATION (EMUTYP_TTY, EMUTYP_ANSI, ...)

Source/HBIOS/hbios.asm

@@ -476,8 +476,24 @@ INT_TIMER:	; TIMER INTERRUPT HANDLER
 ;
 INT_BAD:	; BAD INTERRUPT HANDLER
 	PUSH	HL				; SAVE HL
-	LD	HL,HB_BADINT
-	JR	HBX_INT
+	LD	HL,HB_BADINT			; HL := INT HANDLER IN BIOS BANK
+	JR	HBX_INT				; TO TO ROUTING CODE
+;
+#IF (SIOENABLE)
+INT_SIO:	; SIO DEVICE INTERRUPT HANDLER
+	;PUSH	AF
+	;IN	A,(SIOA_DAT)
+	;LD	A,'='
+	;OUT	(SIOA_DAT),A
+	;POP	AF
+	;EI
+	;RETI
+
+
+	PUSH	HL				; SAVE HL
+	LD	HL,SIO_INT			; HL := SIO INT HANDLER IN BIOS BANK
+	JR	HBX_INT				; TO TO ROUTING CODE
+#ENDIF
 ;
 ; COMMON INTERRUPT DISPATCHING CODE
 ; SETUP AND CALL HANDLER IN BIOS BANK
@@ -791,8 +807,39 @@ HB_START1:			; BNKCALL ARRIVES HERE, BUT NOW RUNNING IN RAM BANK
 ;	
 #ENDIF
 ;
+#IF (INTTYPE == IT_RC)
+;
+	; SETUP Z80 IVT
+	LD	A,HBX_IVT >> 8		; SETUP HI BYTE OF IVT ADDRESS
+	LD	I,A			; ... AND PLACE IT IN I REGISTER
+;
+	IM	2			; SWITCH TO INT MODE 2
+;
+#IF (SIOENABLE)
+	; SETUP SIO INTERRUPT VECTOR IN IVT
+	LD	HL,INT_SIO
+	LD	(HBX_IVT + 4),HL
+#ENDIF
+	
+	
+	
+	
+;
+;	IM	1
+;
+;#IF (SIOENABLE)
+;;
+;	; SETUP SIO INT VECTOR VIA INT MODE 1 IN PAGE ZERO
+;	;LD	A,$C3			; JP OPCODE
+;	;LD	($38),A			; ... AT INT VECTOR ADDRESS
+;	;LD	HL,INT_SIO		; ADDRESS OF SIO INT HANDLER
+;	;LD	($39),HL		; ... IS TARGET OF JP
+;;
+;#ENDIF
+;
+#ENDIF
+;
 #ENDIF
-
 	HB_EI				; END OF CRITICAL SECTION
 ;
 ; DISPLAY PLATFORM INFORMATION

Source/HBIOS/ide.asm

@@ -38,7 +38,7 @@
 ;	| IDE_IO_STAT		| 0x07	| R	| STATUS REGISTER		|
 ;	| IDE_IO_CMD		| 0x07	| W	| COMMAND REGISTER (EXECUTE)	|
 ;	+-----------------------+-------+-------+-------------------------------+
-;	* LBA0-4 ARE ALTERNATE DEFINITIONS OF SECT, CYL, AND DRVHD PORTS
+;	* LBA0-3 ARE ALTERNATE DEFINITIONS OF SECT, CYL, AND DRVHD PORTS
 ;
 ;	=== STATUS REGISTER ===
 ;

Source/HBIOS/sio.asm

@@ -11,10 +11,17 @@
 ;    F   E   D   C   B   A   9   8     7   6   5   4   3   2   1   0
 ;       -- MSB (D REGISTER) --           -- LSB (E REGISTER) --
 ;
-SIO_DEBUG		.EQU	FALSE
-;
-SIO_NONE		.EQU	0
-SIO_SIO			.EQU	1
+SIO_DEBUG	.EQU	FALSE
+;               
+SIO_NONE	.EQU	0
+SIO_SIO		.EQU	1
+;               
+;               
+;               
+SIOA_CMD	.EQU	$80
+SIOA_DAT	.EQU	$81
+SIOB_CMD	.EQU	$82
+SIOB_DAT	.EQU	$83
 ;
 ;
 ;
@@ -24,6 +31,8 @@ SIO_PREINIT:
 ;
 	LD	B,SIO_CNT		; LOOP CONTROL
 	LD	C,0			; PHYSICAL UNIT INDEX
+	XOR	A			; ZERO TO ACCUM
+	LD	(SIO_DEV),A		; CURRENT DEVICE NUMBER
 SIO_PREINIT0:	
 	PUSH	BC			; SAVE LOOP CONTROL
 	LD	A,C			; PHYSICAL UNIT TO A
@@ -51,10 +60,11 @@ SIO_PREINIT0:
 SIO_PREINIT2:	
 	INC	C			; NEXT PHYSICAL UNIT
 	DJNZ	SIO_PREINIT0		; LOOP UNTIL DONE
+;	
 	XOR	A			; SIGNAL SUCCESS
 	RET				; AND RETURN
 ;
-;
+; SIO INITIALIZATION ROUTINE
 ;
 SIO_INITUNIT:
 	CALL	SIO_DETECT		; DETERMINE SIO TYPE
@@ -89,6 +99,8 @@ SIO_INIT1:
 	PUSH	HL			; COPY CFG DATA PTR
 	POP	IY			; ... TO IY
 	
+	LD	A,(IY + 1)		; GET SIO TYPE
+	OR	A			; SET FLAGS
 	CALL	NZ,SIO_PRTCFG		; PRINT IF NOT ZERO
 	
 	POP	BC			; RESTORE LOOP CONTROL
@@ -98,6 +110,78 @@ SIO_INIT1:
 	XOR	A			; SIGNAL SUCCESS
 	RET				; DONE
 ;
+; INTERRUPT HANDLER
+;
+SIO_INT:
+	; CHECK FOR RECEIVE PENDING ON CHANNEL A
+	XOR	A			; A := 0
+	OUT	(SIOA_CMD),A		; ADDRESS RD0
+	IN	A,(SIOA_CMD)		; GET RD0
+	RRA				; RECEIVE READY BIT TO CF
+	JR	NC,SIOB_INT		; NOTHING HERE, TRY B CHANNEL
+;
+	; HANDLE CHANNEL A
+	IN	A,(SIOA_DAT)		; READ PORT
+	LD	E,A			; SAVE BYTE READ
+	LD	A,(SIOA_CNT)		; GET CURRENT BUFFER USED COUNT
+	CP	SIOA_BUFSZ		; COMPARE TO BUFFER SIZE
+	RET	Z			; BAIL OUT IF BUFFER FULL, RCV BYTE DISCARDED
+	INC	A			; INCREMENT THE COUNT
+	LD	(SIOA_CNT),A		; AND SAVE IT
+	CP	SIOA_BUFSZ - 5		; BUFFER GETTING FULL?
+	JR	NZ,SIOA_INT0		; IF NOT, BYPASS CLEARING RTS
+	LD	A,5			; RTS IS IN WR5
+	OUT	(SIOA_CMD),A		; ADDRESS WR5
+	LD	A,$E8			; VALUE TO CLEAR RTS
+	OUT	(SIOA_CMD),A		; DO IT
+SIOA_INT0:
+	LD	HL,(SIOA_HD)		; GET HEAD POINTER
+	LD	A,L			; GET LOW BYTE
+	CP	SIOA_BUFEND & $FF	; PAST END?
+	JR	NZ,SIO_INT1		; IF NOT, BYPASS POINTER RESET
+	LD	HL,SIOA_BUF		; ... OTHERWISE, RESET TO START OF BUFFER
+SIO_INT1:
+	LD	A,E			; RECOVER BYTE READ
+	LD	(HL),A			; SAVE RECEIVED BYTE TO HEAD POSITION
+	INC	HL			; INCREMENT HEAD POINTER
+	LD	(SIOA_HD),HL		; SAVE IT
+	RET				; AND RETURN
+;
+SIOB_INT:
+	; CHECK FOR RECEIVE PENDING ON CHANNEL B
+	XOR	A			; A := 0
+	OUT	(SIOB_CMD),A		; ADDRESS RD0
+	IN	A,(SIOB_CMD)		; GET RD0
+	RRA				; RECEIVE READY BIT TO CF
+	RET	NC			; NOTHING HERE, GIVE UP
+;
+	; HANDLE CHANNEL B
+	IN	A,(SIOB_DAT)		; READ PORT
+	LD	E,A			; SAVE BYTE READ
+	LD	A,(SIOB_CNT)		; GET CURRENT BUFFER USED COUNT
+	CP	SIOB_BUFSZ		; COMPARE TO BUFFER SIZE
+	RET	Z			; BAIL OUT IF BUFFER FULL, RCV BYTE DISCARDED
+	INC	A			; INCREMENT THE COUNT
+	LD	(SIOB_CNT),A		; AND SAVE IT
+	CP	SIOB_BUFSZ - 5		; BUFFER GETTING FULL?
+	JR	NZ,SIOB_INT0		; IF NOT, BYPASS CLEARING RTS
+	LD	A,5			; RTS IS IN WR5
+	OUT	(SIOB_CMD),A		; ADDRESS WR5
+	LD	A,$E8			; VALUE TO CLEAR RTS
+	OUT	(SIOB_CMD),A		; DO IT
+SIOB_INT0:
+	LD	HL,(SIOB_HD)		; GET HEAD POINTER
+	LD	A,L			; GET LOW BYTE
+	CP	SIOB_BUFEND & $FF	; PAST END?
+	JR	NZ,SIOB_INT1		; IF NOT, BYPASS POINTER RESET
+	LD	HL,SIOB_BUF		; ... OTHERWISE, RESET TO START OF BUFFER
+SIOB_INT1:
+	LD	A,E			; RECOVER BYTE READ
+	LD	(HL),A			; SAVE RECEIVED BYTE TO HEAD POSITION
+	INC	HL			; INCREMENT HEAD POINTER
+	LD	(SIOB_HD),HL		; SAVE IT
+	RET				; AND RETURN
+;
 ;
 ;
 SIO_DISPATCH:
@@ -127,10 +211,65 @@ SIO_FTBL:
 ;
 ;
 SIO_IN:
-	CALL	SIO_IST			; RECEIVED CHAR READY?
-	JR	Z,SIO_IN		; LOOP IF NOT
-	LD	C,(IY + 2)		; C := BASE SIO PORT (WHICH IS ALSO RBR REG)
-	IN	E,(C)			; CHAR READ TO E
+	LD	A,(IY + 0)		; GET DEVICE NUMBER
+	OR	A			; SET FLAGS
+	JR	Z,SIOA_IN		; HANDLE CHANNEL A
+	DEC	A			; TEST FOR NEXT DEVICE
+	JR	Z,SIOB_IN		; HANDLE CHANNEL B
+	CALL 	PANIC			; ELSE FATAL ERROR
+	RET				; ... AND RETURN
+;
+SIOA_IN:
+	CALL	SIOA_IST		; RECEIVED CHAR READY?
+	JR	Z,SIOA_IN		; LOOP TILL WE HAVE SOMETHING IN BUFFER
+	DI				; AVOID COLLISION WITH INT HANDLER
+	LD	A,(SIOA_CNT)		; GET COUNT
+	DEC	A			; DECREMENT COUNT
+	LD	(SIOA_CNT),A		; SAVE SAVE IT
+	CP	5			; BUFFER LOW THRESHOLD
+	JR	NZ,SIOA_IN0		; IF NOT, BYPASS SETTING RTS
+	LD	A,5			; RTS IS IN WR5
+	OUT	(SIOA_CMD),A		; ADDRESS WR5
+	LD	A,$EA			; VALUE TO SET RTS
+	OUT	(SIOA_CMD),A		; DO IT
+SIOA_IN0:
+	LD	HL,(SIOA_TL)		; GET BUFFER TAIL POINTER
+	LD	E,(HL)			; GET BYTE
+	INC	HL			; BUMP TAIL POINTER
+	LD	A,L			; GET LOW BYTE
+	CP	SIOA_BUFEND & $FF	; PAST END?
+	JR	NZ,SIOA_IN1		; IF NOT, BYPASS POINTER RESET
+	LD	HL,SIOA_BUF		; ... OTHERWISE, RESET TO START OF BUFFER
+SIOA_IN1:
+	LD	(SIOA_TL),HL		; SAVE UPDATED TAIL POINTER
+	EI				; INTERRUPTS OK AGAIN
+	XOR	A			; SIGNAL SUCCESS
+	RET				; AND DONE
+;
+SIOB_IN:
+	CALL	SIOB_IST		; RECEIVED CHAR READY?
+	JR	Z,SIOB_IN		; LOOP TILL WE HAVE SOMETHING IN BUFFER
+	DI				; AVOID COLLISION WITH INT HANDLER
+	LD	A,(SIOB_CNT)		; GET COUNT
+	DEC	A			; DECREMENT COUNT
+	LD	(SIOB_CNT),A		; SAVE SAVE IT
+	CP	5			; BUFFER LOW THRESHOLD
+	JR	NZ,SIOB_IN0		; IF NOT, BYPASS SETTING RTS
+	LD	A,5			; RTS IS IN WR5
+	OUT	(SIOA_CMD),A		; ADDRESS WR5
+	LD	A,$EA			; VALUE TO SET RTS
+	OUT	(SIOA_CMD),A		; DO IT
+SIOB_IN0:
+	LD	HL,(SIOB_TL)		; GET BUFFER TAIL POINTER
+	LD	E,(HL)			; GET BYTE
+	INC	HL			; BUMP TAIL POINTER
+	LD	A,L			; GET LOW BYTE
+	CP	SIOB_BUFEND & $FF	; PAST END?
+	JR	NZ,SIOB_IN1		; IF NOT, BYPASS POINTER RESET
+	LD	HL,SIOB_BUF		; ... OTHERWISE, RESET TO START OF BUFFER
+SIOB_IN1:
+	LD	(SIOB_TL),HL		; SAVE UPDATED TAIL POINTER
+	EI				; INTERRUPTS OK AGAIN
 	XOR	A			; SIGNAL SUCCESS
 	RET				; AND DONE
 ;
@@ -147,14 +286,24 @@ SIO_OUT:
 ;
 ;
 SIO_IST:
-	LD	C,(IY + 3)		; CMD PORT
-	XOR	A			; WR0
-	OUT	(C),A			; DO IT
-	IN	A,(C)			; GET STATUS
-	AND	$01			; ISOLATE BIT 0 (RECEIVE DATA READY)
+	LD	A,(IY + 0)		; GET DEVICE NUMBER
+	OR	A			; SET FLAGS
+	JR	Z,SIOA_IST		; HANDLE CHANNEL A
+	DEC	A			; TEST FOR NEXT DEVICE
+	JR	Z,SIOB_IST		; HANDLE CHANNEL B
+	CALL 	PANIC			; ELSE FATAL ERROR
+	RET				; ... AND RETURN
+;
+SIOA_IST:
+	LD	A,(SIOA_CNT)		; GET BUFFER UTILIZATION COUNT
+	OR	A			; SET FLAGS
+	JP	Z,CIO_IDLE		; NOT READY, RETURN VIA IDLE PROCESSING
+	RET				; AND DONE
+;
+SIOB_IST:
+	LD	A,(SIOB_CNT)		; GET BUFFER UTILIZATION COUNT
+	OR	A			; SET FLAGS
 	JP	Z,CIO_IDLE		; NOT READY, RETURN VIA IDLE PROCESSING
-	XOR	A			; ZERO ACCUM
-	INC	A			; ACCUM := 1 TO SIGNAL 1 CHAR WAITING
 	RET				; DONE
 ;
 ;
@@ -183,7 +332,9 @@ SIO_INITDEV:
 SIO_INITVALS:
 	.DB	$00, $18	; WR0: CHANNEL RESET
 	.DB	$04, $C4	; WR4: CLK/64=115200 BAUD, NO PARITY, 1 STOP BIT
-	.DB	$01, $00	; WR1: NO INTERRUPTS
+;	.DB	$01, $00	; WR1: NO INTERRUPTS
+	.DB	$01, $18	; WR1: INTERRUPT ON ALL RECEIVE CHARACTERS
+	.DB	$02, $04	; WR2: INTERRUPT VECTOR OFFSET
 	.DB	$03, $C1	; WR3: 8 BIT RCV, RX ENABLE
 	.DB	$05, $EA	; WR5: DTR, 8 BITS SEND,  TX ENABLE, RTS
 SIO_INITLEN	.EQU	$ - SIO_INITVALS
@@ -270,22 +421,38 @@ SIO_STR_SIO	.DB	"SIO$"
 ;
 SIO_DEV		.DB	0		; DEVICE NUM USED DURING INIT
 ;
+; CHANNEL A RECEIVE BUFFER
+SIOA_CNT	.DB	0		; CHARACTERS IN RING BUFFER
+SIOA_BUF	.FILL	32,'%'		; RECEIVE RING BUFFER
+SIOA_BUFEND	.EQU	$		; END OF BUFFER
+SIOA_BUFSZ	.EQU	$ - SIOA_BUF	; SIZE OF RING BUFFER
+SIOA_HD		.DW	SIOA_BUF	; BUFFER HEAD POINTER
+SIOA_TL		.DW	SIOA_BUF	; BUFFER TAIL POINTER
+;
+; CHANNEL B RECEIVE BUFFER
+SIOB_CNT	.DB	0		; CHARACTERS IN RING BUFFER
+SIOB_BUF	.FILL	32,'%'		; RECEIVE RING BUFFER
+SIOB_BUFEND	.EQU	$		; END OF BUFFER
+SIOB_BUFSZ	.EQU	$ - SIOB_BUF	; SIZE OF RING BUFFER
+SIOB_HD		.DW	SIOB_BUF	; BUFFER HEAD POINTER
+SIOB_TL		.DW	SIOB_BUF	; BUFFER TAIL POINTER
+;
 ; SIO PORT TABLE
 ;
 SIO_CFG:
 	; SIO/2 CHANNEL A
 	.DB	0			; DEVICE NUMBER (UPDATED DURING INIT)
 	.DB	0			; SIO TYPE
-	.DB	$81			; DATA PORT
-	.DB	$80			; CMD PORT
+	.DB	SIOA_DAT		; DATA PORT
+	.DB	SIOA_CMD		; CMD PORT
 	.DW	DEFSERCFG		; LINE CONFIGURATION
 	.FILL	2,$FF			; FILLER
 ;
 	; SIO/2 CHANNEL B
 	.DB	0			; DEVICE NUMBER (UPDATED DURING INIT)
 	.DB	0			; SIO TYPE
-	.DB	$83			; DATA PORT
-	.DB	$82			; CMD PORT
+	.DB	SIOB_DAT		; DATA PORT
+	.DB	SIOB_CMD		; CMD PORT
 	.DW	DEFSERCFG		; LINE CONFIGURATION
 	.FILL	2,$FF			; FILLER
 ;

Source/HBIOS/std.asm

@@ -163,6 +163,7 @@ IT_NONE		.EQU	0
 IT_SIMH		.EQU	1
 IT_Z180		.EQU	2
 IT_CTC		.EQU	3
+IT_RC		.EQU	4
 ;
 #INCLUDE "build.inc"			; INCLUDE USER CONFIG, ADD VARIANT, TIMESTAMP, & ROMSIZE
 ;

Source/HBIOS/uart.asm

@@ -116,7 +116,6 @@ UART_INITUNIT:
 ;
 ;
 ;
-;
 UART_INIT:
 	LD	B,UART_CNT		; COUNT OF POSSIBLE UART UNITS
 	LD	C,0			; INDEX INTO UART CONFIG TABLE