MAL EXIT) WITH THE C(AC)=0. POSSIBLE RETURN
/CONDITIONS ARE: 1) BUFFER IS EMPTY;  2) ^Z WAS FOUND IN BUFFER. A ^C WILL
/RETURN TO MONITOR AT 7600. XON/XOFF IS RECOGNIZED FOR THE OUTPUT DEVICE.
XMIT,	TAD CRCHAR	/SEND ONE TIME CR TO MAKE BASIC HAPPY
	JMS I IXMIT6
	DCA XMIT
	DCA XMIT+1
XMIT1,	ISZ WRDCNT
	JMP XMIT1A
EXIT5,	TAD ZEROSW
	SZA CLA
	ISZ ENTRY
XITFLD,	CDFIFX
	JMP/COM1.PA

/ORIGN SERIAL.PA

/COPYRIGHT  (C) 1981, 1982,1984 BY DIGITAL EQUIPMENT CORPORATION

/THE INFORMATION IN THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE
/AND SHOULD NOT BE CONSTRUED AS A COMMITMENT BY DIGITAL EQUIPMENT
/CORPORATION.  DIGITAL EQUIPMENT CORPORATION ASSUMES NO RESPONSIBILITY
/FOR ANY ERRORS THAT MAY APPEAR IN THIS DOCUMENT.

/THE SOFTWARE DESCRIBED IN THIS DOCUMENT IS FURNISHED TO THE PURCHASER
/UNDER A LICENSE FOR USE ON A SINGLE COMPUTER SYSTEM AND CAN BE COPIED
/(WITH INCLUSION OF DIGITAL'S COPYRIGHT NOTICE) ONLY FOR USE IN SUCH
/SYSTEM, EXCEPT AS MAY OTHERWISE BE PROVIDED IN WRITING BY DIGITAL.

/DIGITAL EQUIPMENT CORPORATION ASSUMES NO RESPONSIBILITY FOR THE USE
/OR RELIABILITY OF ITS SOFTWARE ON EQUIPMENT THAT IS NOT SUPPLIED BY
/DIGITAL.



	VERSION="B&77^100+63	/ VER B3

	NOCHK=0	/ 0 = No ctrl c check, 1 = check

	AC0004=CLA CLL IAC RTL
	AC100=CLA IAC BSW
	AC4000=CLA STL RAR
	ACM2=CLL CLA CMA RAL
	BSW=7002
	XON="Q&277
	XOFF="S&277
	CDFXXX=HLT
	CDFIFX=HLT

	RECEIVE=34
	TRANSMIT=RECEIVE+1

	XMTSKP=TRANSMIT^10+6001
	XMTLOD=TRANSMIT^10+6006

	RECSKP=RECEIVE^10+6001
	RECLOD=RECEIVE^10+6006

	*0
	7777
	DEVICE COM1
	DEVICE COM1
	0050
	ENTRY&177+4000
	0000
	0000

	*200


RENTRY,
ZEROSW,			/WHEN CLEAR, BUFFER IS BEING ZEROED PRIOR TO EXIT.
BUFRFD,	CDFXXX
	ISZ RXSWITCH	/IF -1, FUNCTION IS XMIT
	JMP RECV0	/INPUT

/TRANSMIT ROUTINES. THERE ARE NO "ERROR CONDITIONS" FOR OUTPUT. ALL TERMINATION
/WILL RETURN TO CALLER AT +5 (NORUSED TO PROTECT ISZ)
	TAD LF
	DCA I BUFRPT
	ISZ BUFRPT
XXOFF,	XOFF
	JMP ZMINCR

XXON,	XON
WRDCNT,	0
K70,	70
BUFRAD,	0
BUFRPT,	0
RXSWITCH,
CHAR3,	0	
MINZ,	-232		/-^Z
CRMLF,	15-12

/			TRAILING DATA BLOCK FOR HANDLER CALL:

/	WORD	1 FUNCTION WORD  _ _ _ ! _ _ _ ! _ _ _ ! _ _ _
/				 ! \ 	     /   FIELD   UNUSED
/		       4000= WRITE   DOUBLE      OF      IN 
/		 I ENTRY
XMIT1A,	STL
	RTL
	RTL
	SPA
	JMP XMIT1B	/FOR CHAR3
	DCA CHAR3
	TAD I BUFRPT
	JMS I IXMIT
	TAD I BUFRPT
	ISZ BUFRPT
	7400		/SERVES AS A NOP TO PROTECT ISZ
	AND .-1
	CLL RAL
	TAD CHAR3
	JMP XMIT1A+1
XMIT1B,	JMS I IXMIT
	JMP XMIT1	/FOR ANOTHER PASS

CDFCIF,	CDF CIF 0
K3700,	3700
CRCHAR,	215

IXMIT,	XMIT2-PAGE2
IXMIT6,	XMIT6-PAGE2
IDEVINPUT,DEVINPUT-PAGE2


/INPUT ROUTINES. ACCEPTS INPUT FROM THE DEVICE AND RETURNS 8-BIT ASCII
/TO THE CALLING PROGRAM BUFFER. INPUT CHARACTERS ARE SCREENED FOR A
/^Z, CR(LF).  ^Z IS THE ONLY CHARACTER THAT WILL CAUSE
/AN "ERROR" EXIT. THERE ARE NO FATAL ERRORS. ^Z AND CR WILL ECHO CRLF, PAD
/THE CALLING PROGRAM BUFFER WITH ZERO BEFORE EXITING.

RECV0,	TAD WRDCNT
	CLL IAC RAL	/INPUT RETURNS 1 8BIT PER 1 12BIT WORD TO CALLER.
	DCA WRDCNT
	TAD XXON
	JMS I IXMIT6
RECV1,	TAD ZEROSW	/WHEN ZERO, WE ARE PADDING USER BUFFER PRIOR TO EXIT.
	SZA CLA
	JMS I IDEVINPUT	/GET A CHARACTER FROM INPUT.
RECV1A,	DCA I BUFRPT	/RETURNS 8BIT ASCII.
	TAD I BUFRPT	/USE THE CALLING BUFFER FOR TEMP STORAGE.
	TAD MINZ	/-^Z (-232)
	SNA
	JMP XITFLD	/^Z FOUND EXIT
	TAD ZMINCR	/^Z-CR (32-15)
	SNA
	JMP RECV6	/CARRIAGE RETURN
	TAD CRMLF	/CR-LF  (15-12)
	SNA CLA
	JMP RECV1	/DON'T PASS LINE FEEDS
	ISZ BUFRPT	/UPDATE BUFFER POINTER
ZMINCR,	32-15
	ISZ WRDCNT
	JMP RECV1	/FOR THE NEXT
	JMP EXIT5

RECV6,	ISZ ENTRY	/SINCE A "CLEAR" ZEROSWITCH WON'T BUMP IT FOR EXIT.
	DCA ZEROSW
	TAD XXOFF
	JMS I IXMIT6	/SEND XOFF AFTER CR
	ISZ BUFRPT
LF,	212		/(LINEFEED;        0000= INPUT   WORDS ^100  BUFFER  OS/78

/	WORD	2 ADDRESS OF BUFFER
/	WORD	3 STARTING BLOCK. IF 0, MAY DO SPECIAL INIT ROUTINES;
/			          OTHERWISE IS IGNORED FOR THIS HANDLER
/	WORD	4 ERROR. IF AC IS POSITIVE, ERROR IS NOT CONSIDERED FATAL.
/	WORD	5 NORMAL RETURN. AC IS 0.


	*350
ENTRY,	VERSION
	AC4000		/FORCE THE WRITE (OUTPUT BIT) INTO THE LINK IF
	TAD I ENTRY	/PRESENT WHEN GETTING THE FUNCTION WORD. MUST BE
	AND K70		/PRESERVED WHILE FETCHING REST OF DATA BLOCK.
	TAD CDF0
	DCA BUFRFD	/GET THE FIELD OF THE BUFFER
	SZL
	STA
	DCA RXSWITCH	/0=RECEIVE; -1=XMIT
	TAD K3700	/AND THE "DOUBLE WORDS". FOR OUTPUT, WILL REPRESENT
	AND I ENTRY	/2 PACKED WORDS OF 3 ASCII CHARS. IF INPUT, WILL BE
	CMA		/DOUBLED TO COUNT 1 8BIT CHARACTER FOR EACH 12BIT WORD.
			/NOTE: OS/8 ROUTINES CAN REQUEST THE PROCESSING OF A
			/NULL BUFFER (ZERO DOUBLE WORDS). IF SOME SPECIAL
			/ACTION IS REQUIRED, E.G. WRITING EOF OR DOING FORM
			/FEED, THE WORD COUNT WILL BE ZERO. THIS HANDLER MAY
			/OR MAY NOT HAVE SPECIAL FUNCTIONS, DEPENDING UPON
			/ASSEMBLY SPECIFICATIONS.
	DCA WRDCNT
	ISZ ENTRY
	TAD I ENTRY	/GET THE STARTING ADDRESS OF THE BUFFER.
	DCA BUFRAD
	TAD BUFRAD
	DCA BUFRPT	/WILL HAVE CURRENT POSITION OF USER'S BUFFER.
	ISZ ENTRY	/SKIP THE BLOCK NUMBER (THIS IS NON-FILE STRUCTURED)
	ISZ ENTRY	/AND LEAVE RETURN POINTING TO ERROR.
	RDF		/DATA FIELD IS SET TO CALL; INSTRUCTION FIELD IS HERE.
	TAD CDFCIF
	DCA XITFLD	/WHEN EXITING, IF/DF IS SET TO CALLING ROUTINE.
CDF0,	CDF 0		/FALL THRU TO NEXT PAGE FOR INDIRECT ADDRESS ADJUSTMENT
	PAGE


/PROCEDURE FOR ADJUSTING THE ABSOLUTE ADDRESSES OF INDIRECT LOCATIONS:

/THIS HANDLER IS ASSEMBLED WITH A STARTING LOCATION OF 200. THIS IS PARTLY
/ARBITRARY AND PARTLY BECAUSE OF THE REQUIREMENTS OF THE BUILD PROGRAM.
/A "MARK" IS ESTABLISHED TO BE USED DURING ASSEMBLY TIME TO SET THE VALUE
/OF THE INDIRECT ADDRESS POINTERS TO THE RELATIVE DIFFERENCE BETWEEN THE 
/POINTER AND THE ROUTINE REQUESTED. FOR CONVENIENCE, THIS MARKER IS CALLED
/"PAGE2" AND IS ESTABLISHED AT THE TOP OF THE SECOND PAGE. THE ADJUSTMENT
/ROUTINE FINDS THE BASE ABSOLUTE ADDRESS FROM THE "JMS ." THEN ADDS IT
/TO THE THE VALUE IN "DIFFTABLE". THE CONTENTS OF DIFFTABLE ARE THE
/RELATIVE DIFFERENCES BETWEEN PAGE2 AND THE INDIRECT ADDRESS POINTERS TO
/BE MODIFIED. THIS DIFFERENCE PLUS THE BASE ABSOLUTE ADDRESS FORMS AN
/ABSOLUTE POINTER TO THE ADDRESS TO BE MODIFIED. THE CONTENTS OF THE AD-
/DRESS TO BE MODIFIED IS ALSO THE RELATIVE DIFFERENCE BETWEEN THE MARK
/AND THE ADDRESS DESIRED. USING THE TEMPORARY ABSOLUTE POINTER, THIS DIF-
/FERENCE IS ADDED TO THE BASE ADDRESS THEN RESTORED TO THE INDIRECT
/POINTER AS AN ABSOLUTE VALUE.



ENTRY1,	NOP		/GETS JMP I IRENTRY AFTER INIT.
PAGE2A,	JMS .		/TO FIND OUT WHERE WE ARE. LEAVE 2A SO WE CAN MOVE.
PAGE2,
ADJUST,	TAD DIFFTABLE
	SNA
	JMP ALLSET
	TAD PAGE2A	/AS THE BASE.
	DCA TEMPOINT
	TAD I TEMPOINT
	TAD PAGE2A
	DCA I TEMPOINT
	ISZ ADJUST
	JMP ADJUST

XMIT6,	0
	TAD (400
	XMTLOD
	XMTSKP
	JMP .-1
OS8MON,	7600		/USE A GROUP 2 CLA TO GET THE MONITOR RETURN POINT.
	JMP I XMIT6

IEXIT5,	EXIT5-PAGE2
IRENTRY,RENTRY-PAGE2

DIFFTA,	IXMIT-PAGE2	/SET UP CROSS PAGE LINKAGE
	IXMIT6-PAGE2
	IDEVINPUT-PAGE2
XMIT3,	IEXIT5-PAGE2
XOFFLAG,IRENTRY-PAGE2

XMIT2,	0		/SCREEN CHARACTER BEFORE OUTPUT
	AND (177
	TAD (200
	DCA XMIT3	/SAVE CHARACTER.
	JMS CHKTTY
XMIT2B,	JMS DEVIN1	/CHECK DEVICE FOR XON/OFF
	SNA
	JMP XMIT2D	/NO FLAG
	TAD (-XON
	SNA
	JMP XMIT2A
	TAD (XON-XOFF
	SNA CLA
	JMP XMIT2C	/SET XOFF FLAG
XMIT2D,	ISZ XOFFLAG	/WORKING ON XOFF ALREADY?
	JMP XMIT2A	/NO. IGNORE THE INPUT
XMIT2C,	STA		/[RE]SET THE FLAG
	DCA XOFFLAG
	JMP XMIT2B	/AND KEEP LOOKING.
XMIT2A,	DCA XOFFLAG	/KEEP CLEARED WHEN NOT WORKING ON XOFF.
	TAD XMIT3
	TAD (-232
	SNA
	JM,0
	JMS CHKTTY
	JMS DEVIN1
	SNA
	JMP DEVINPUT+1	/WAIT HERE FOR SOME INPUT
	JMP I DEVINPUT

DEVIN1,	0
	RECSKP
	JMP I DEVIN1	/NO FLAG.
	RECLOD
	SNA		/FILTER NULLS
	JMP DEVIN1+1
	AND (177
	TAD (200
	JMP I DEVIN1	/WITH 8BIT.

CHKTTY,	0
IFNZRO	NOCHK < KSF >
IFZERO	NOCHK < NOP >
	JMP I CHKTTY
	KRB
	AND (177
	TAD (-3		/IS IT A CTRL C
	SZA CLA
	JMP I CHKTTY
	CDF CIF 0
	JMP I OS8MON	/BEFORE EXITING TO MONITOR