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Trailing-Edge - PDP-10 Archives - bb-bt99m-bb - ddt.p11
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; 16 OCT 79
;COPYRIGHT (C) 1978,1979,1980,1981,1984 BY DIGITAL EQUIPMENT CORP., MAYNARD, MASS.

VRDDT=5
END$$=0
.IF NDF FT.DDT
 FT.DDT=1
 END$$=1
.ENDC
.IF NE FT.DDT
; THIS IS DDT: DYNAMIC DEBUGGING TECHNIQUE FOR A PDP-11.
; IT RESEMBLES DDT FOR A PDP-10 IN AS MANY WAYS AS POSSIBLE
; AND FALLS SHORT ONLY SLIGHTLY DUE TO THE VARIETY OF PDP-11
; CONFIGURATIONS AVAILABLE.
;
; AUTHOR: STEVEN M. RUBIN (SR12) AT CARNEGIE-MELLON UNIVERSITY
;MUNGED BY RIC WERME FOR INHOUSE DEBUGGING OF THE DN87S
;MUNGED SOME MORE BY RDH FOR SAME.

.=1000
.ENABL	AMA,LC

; UN-COMMENT THE NEXT LINE IF DDT IS TO RUN ON AN LSI-11
;D.LSI	=	1		; DEFINED IF PROCESSOR IS AN LSI-11

; THE NEXT THREE DEFINES DESCRIBE THE MAIN OUTPUT DEVICE THAT
; DDT WILL USE.  ONLY 1 MAY BE DEFINED AND THE REST MUST BE
; COMMENTED OUT.
;D.GDP	=	1 		; TTY IS GRAPHICS DISPLAY PROCESSOR
D.KSR	=	1 		; TTY IS KSR-33
;D.GT40	=	1 		; TTY IS DEC GT40

	.IF	DF,D.LSI
;.PRINT	 ; *****DDT for an LSI-11*****
	 .ENABLE NSF
	 .OPDEF	MFPS,TST,106700
	 .OPDEF	MTPS,TST,106400
	.ENDC
	D.OKTTY=-1
	.IF	DF,D.GDP
	 D.OKTTY=D.OKTTY+1
	 .TITLE	D.GDP
;.PRINT	 ; *****DDT for a GDP*****
D.RDB	 =	165202		; READER DATA BUFFER
D.RCSR	 =	165200		; READER STATUS REGISTER
D.PRIO	 =	0		; RUN AT PRIORITY ZERO
	.ENDC
	.IF	DF,D.GT40
	 D.OKTTY=D.OKTTY+1
	 .TITLE	D.GT40
;.PRINT	 ; *****DDT for a GT40*****
D.RCSR	 =	177560		; READER STATUS REGISTER
D.RDB	 =	177562		; READER DATA BUFFER
D.PRIO	 =	200		; RUN AT PRIORITY FOUR
	.ENDC
	.IF	DF,D.KSR
	 D.OKTTY=D.OKTTY+1
	 .TITLE	D.KSR
	.IF EQ <PASS-2>
;.PRINT	 ; *****DDT for a TTY*****
	.ENDC
D.RCSR	 =	177560		; READER STATUS REGISTER
D.RDB	 =	177562		; READER DATA BUFFER
D.TCSR	 =	177564		; PRINTER STATUS REGISTER
D.TDB	 =	177566		; PRINTER DATA BUFFER
D.PRIO	 =	340		; RUN AT PRIORITY SEVEN
	.ENDC

.IIF NE,D.OKTTY,.ERROR	; INVALID OUTPUT DEVICE FOR DDT

D.BKP	=	8.		; NUMBER OF BREAKPOINTS
D.SYML	=	10.		; MAX NUMBER CHARS IN A SYMBOL
.IF NE END$$
R0	=	%0
R1	=	%1
R2	=	%2
R3	=	%3
R4	=	%4
R5	=	%5
SP	=	%6
PC	=	%7
PS	=	177776		; PROCESSOR STATUS
.ENDC

.IF NE,0
	DDT/11 - Dynamic Debugging Technique on the PDP-11

Each  command in DDT/11  is identical to the  PDP-10 version whenever
possible.   In some cases,  DDT/10 commands have been  omitted in the
interest  of saving core and  making good sense.  The  following is a
list of the DDT/11 commands:
 n/	Open word n.  Type contents in current mode
  /	Open word pointed to by last typed value
 n<CR>	Modify currently open word to be n.  Close word.
 n<LF>	Modify, close, open next word
 n^	Modify, close, open previous word
 n<TAB>	Modify, close, open word pointed to by last typed address
 n\	Modify, close, examine word n
  \	Examine word pointed to by last typed value
  $S	Change current mode to instruction type out ($$S for permanence)
  $A	Addresses will be typed as absolute numbers ($$A for permanence)
  $R	Addresses will be typed relative to symbols ($$R for permanence)
  $C	Change current mode to numeric type out ($$C for permanence)
 $nR	Change current radix for $C to n (n read in decimal, $$nR for permanence)
  $T	Change current mode to ASCII text output ($$T for permanence)
 $5T	Change current mode to Radix-50 text output ($$5T for permanence)
 $nO	Change current mode to n bit byte typeout ($$nO for permanence)
  $H	Change to halfword (byte) mode ($$H for permanence; reset by $5T and $S)
 n[	Open location n, type as a numeric
 n]	Open location n, type as instruction
 n!	Open location n, do not type value
  ;	Retype currently open word
  =	Retype currently open word as number
 n=	Type value of n as a number
  _	Retype currently open word as instruction
  i$X	Execute instruction i (don't execute branches)
  n$G	Start executing program at location n.  Default is to
	start executing at address in JOBSA (start of program)
  v$nB	Set breakpoint n at address v (n from 1 to 8 or can be omitted)
a,v$nB	Same as above but open address a at breakpoint
	If two altmodes are used, automatic proceding is enabled.  The
	breakpoint will cause the message to be typed and the program
	resumed.  If you type a character, the automatic proceding will stop.
  0$nB	Remove breakpoint n
   $B	Remove all breakpoints
   $P	Procede from breakpoint
  n$P	Procede from breakpoint n times (without halting)
	If two altmodes are used, the breakpoint will be proceded from automatically
  n$UW	Set offset limit to n (used when typing addresses)
   $1UT	Turn on single stepping (break at each instruction)
  a$1UT	Turn on single stepping and open location a at each break
	If two altmodes are used, the single stepping will be done automatically
   $UT	Turn off single stepping
  a:	Make current location have symbolic name a
v<a:	Make symbolic name a have value v
  a$$K	Delete symbolic name a
  a$K	Delete symbolic name a from typeout only
   $D	Perform an $K on the last symbol coloned (:)
l<u$$Z	Zero memory from l to u
  n$M	Set mask for searches (below) to n
l<u>s$W	Search core from l to u for word s.
l<u>s$E	Search core from l to u for effective address s.
l<u>s$N	Search core from l to u for word not equal to s.
 <CALL>	Soft restart at address 1004 (Graphics DDT only)
Note that numbers can be as any combination of the following:

	<Octal number>
	<Decimal number> .
	<Program symbol>
	" <Delimeter> <Two ASCII Characters> <Delimeter>
	"$ <Delimeter> <Three Radix-50 Characters> <Delimeter>
	<Instruction>

The operators +  (addition), - (subtraction), * (multiplication), and
' (division) are evaluated  from left to right unless parenthesis are
included.  The space is treated like a plus except after instructions
when  it is merely a  separator.   All input is  accepted in lower or
upper case and is folded (except for text.)

If you  are not  in DDT,  you can  re-enter with  a Meta-BREAK  on  a
graphics or  a restart  at DDT  (location typed  out initially).   In
addition to program symbols, the following are also defined for you:

 R0-R5	are the user registers.  R1/ would open register 1.
 SP	is the user's stack pointer
 PC	is the user's program counter
 $I	is the user status
 $2I	is the status of DDT
 $M	is the mask for searches
 $Q	is the value at the current address
 $V	is the value at the current address with the bytes switched
 $nB	is the address of breakpoint n
 JOBSA	is the starting address of your program.
  .	represents the current location.  Thus .$1B puts
	breakpoint 1 at the currently opened location.

When  your program is  executing, the following  unexpected traps may
occur:

   NXM! is caused when your program requests a non-existant memory or
        does a word operation on an odd address.
   ILG! is caused by an illegal instruction.
   BPT! is  caused  by  an  entry  to DDT  that  is  unexpected (i.e.
        executing the BPT instruction or setting the T-bit).

To get DDT, link your  program with SYS:LINK11 and use the /D switch.
In  order for DDT to  know all of your  program symbols, compile your
program  with MACN11 and  use the  .ENABLE ISD switch  to generate an
internal symbol dictionary.

.ENDC
; MAIN LOOP OF DDT

DDT:	BR	D.DDT3		; HARD ENTRY ADDRESS TO DDT
.IIF NDF,D.LSI,MOV @#PS,D.USTA	; GET USER'S STATUS
.IIF DF,D.LSI,MFPS D.USTA	; GET USER'S STATUS
	MOV	(SP)+,D.UR7	; SOFT ENTRY ASSUMES STACK HAS RETURN ADDRESS
	JSR	PC,D.SAVE	; SAVE REGISTERS
	BR	D.DDT2		; FINISH INITIALIZATION
D.DDT3:
.IIF NDF,D.LSI,MOV @#PS,D.USTA	; SAVE USER'S STATUS
	.IF	DF,D.LSI
	 HALT			; HALT TO ALLOW TYPEOUT
	 MFPS	D.USTA		; GET USER'S STATUS
	.ENDC
	CMP	SP,#400		;IS STACK REASONABLE?
	BHI	10$		;YES, SEE IF ITS ADDRESSABLE
	MOV	#D.STK,SP	;NOPE, USE OURS THEN
10$:	MOV	#D.NOSP,@#4	; SET FOR INVALID STACK INTERRUPT
	MOV	#340,@#6	; SET HIGH STATUS
	MOV	#D.ILGT,@#10	; SET FOR ILLEGAL INSTRUCTIONS
	MOV	#340,@#12	; SET HIGH STATUS
	MOV	SP,D.XXX	; SAVE HIS STACK
	MOV	#D.STK,SP	; USE OURS TEMPORARILY
	TST	@D.XXX		; DOES HIS STACK EXIST?
	MOV	D.XXX,SP	; GIVE HIM BACK HIS STACK
D.FIX:	MOV	#D.NXMT,@#4	; RESTORE FOR EXTERNAL NXMS
	MOV	JOBSA,D.UR7	; ASSUME HE CAME FROM STARTING ADDRESS
	JSR	PC,D.SAVE	; SAVE REGISTERS
	.IF	DF,D.GDP
	 MOV	#DDT+2,R0	; ADDRESS OF RESTART FOR MONITOR
	 TRAP	133		; DDTCAL
	.ENDC
	CLRB	D.NOTY		; ALLOW TYPEOUT
	JSR	PC,D.CRLF	; START OUT AT LEFT MARGIN
	MOV	#D.GRET,R4	; TELL YOU ARE HERE
	MOV	#D.GRND,R3	; END OF MESSAGE
	JSR	PC,D.STYP	; TYPE MESSAGE
;	.IF	NDF,D.GDP
;	 MOV	#DDT,R0		; ADDRESS OF RESTART
;	 JSR	PC,D.TYPN	; TYPE RESTART ADDRESS
;	.ENDC
D.DDT2:	JSR	PC,D.CRLF	; TYPE CARRIAGE RETURN-LINE FEED
	CLR	D.SD.T		; NOT IN SINGLE STEP OR TRACE
	MOVB	#-1,D.P		; DISALLOW PROCEDE
	BR	D.DCD0		; GET INTO MAIN LOOP
D.ERR:	MOV	#' ,R0		; TYPE A SPACE
	JSR	PC,D.TYPE
	MOV	#'?,R0		; ? TO BE TYPED
D.ERRO:	JSR	PC,D.TYPE	; TYPE CHARACTER
D.DCD:	JSR	PC,D.TTAB	; TYPE TAB
D.DCD0:	CLR	D.COMA		; NO , PARAMETER.  RETURN FROM <CR>HCTSAR>
	CLRB	D.FWAF		; NO < PARAMETER
.IIF NDF,D.LSI,MOV D.DSTA,@#PS	; SET DDT STATUS
.IIF DF,D.LSI,MTPS D.DSTA	; SET DDT STATUS
	MOV	#NOP,D.PARS	; FILL $X AREA WITH NOPS
	MOV	#NOP,D.PARS+2	;  IN CASE OF SHORT INSTRUCTIONS
	CLR	D.PARO		; NO OFFSET
	CLR	D.PARO+2	; NO OFFSET
D.DCD2:	CLR	D.SVR2		; RETURN FROM ,<
	CLR	D.SVR4		; D.SVR4 IS A SAVE REGISTER FOR R4
	CLR	D.OFST		; TALLY
	CLR	R2		; NUMBER TYPED FLAG
D.DCD3:	CLRB	D.ALTF		; RETURN FROM B"MVQI
D.DCD1:	CLRB	D.LEVL		; RETURN FROM $
	CLRB	D.INPA		; NOT IN INSTRUCTION TYPE-IN
	MOV	D.CAD,D.CADC	; KEEP A CURRENT COPY FOR INST TYPE-IN
	MOV	#D.STK,SP	; RESET STACK POINTER
	JSR	PC,D.EXPR	; GET EXPRESSION (R2,R4,R1)
	TST	R2		; NEED OPERANDS FOR INSTRUCTION?
	BPL	D.DCD4		; BRANCH IF NOT
	JSR	PC,D.GETI	; GET OPERANDS
D.DCD4:	TST	R2		; ANY VALUE TYPED?
	BEQ	D.DCD5		; BRANCH IF NOT
	MOV	R4,D.LASV	; STORE LAST TYPED VALUE
	MOV	R4,D.LASW	; STORE LAST TYPED WORD TOO
D.DCD5:	ASL	R1		; MULTIPLY BY TWO
	JSR	PC,@D.LGDR(R1)	; GO TO PROPER ROUTINE
	BR	D.DCD		; GET NEXT COMMAND
D.NOSP:	MOV	#D.STK,SP	; SET OWN STACK PERMANENTLY FOR USER
	BR	D.FIX		; RETURN
; ROUTINE TO GET A PRIMARY INTO R1 (COMMAND DECODER)

D.PRIM:				; PRIMARY READING SUBROUTINE
	CLR	R4		; R4 CONTAINS THE CONVERTED OCTAL
	CLR	D.DECN		; CLEAR DECIMAL NUMBER
	CLRB	D.USED		; CLEAR USE-DECIMAL NUMBER INDICATOR
	JSR	PC,D.CLSM	; CLEAR SYMBOL
D.PRI1:	JSR	PC,D.GET	; GET A CHAR, RETURN IN R0
	CMP	#'0,R0		; COMPARE WITH ASCII 0
	BHI	D.PRI3		; CHECK LEGALITY IF NON-NUMERIC
	CMP	#'9,R0		; COMPARE WITH ASCII 9
	BLO	D.PRI3		; CHECK LEGALITY IF NOT OCTAL
	CMP	D.POS,#D.SYM	; IN THE MIDDLE OF A SYMBOL?
	BNE	D.PRI6		; YES, PUT DIGIT IN SYMBOL
	SUB	#'0,R0		; CONVERT TO BCD
	ASL	R4		; MAKE ROOM
	ASL	R4		;  IN
	ASL	R4		;    R4
	ADD	R0,R4		; PACK THREE BITS IN R4
	MOV	D.DECN,R1	; GET DECIMAL NUMBER
	ASL	R1		; MULTIPLY BY 2
	ADD	R1,R0		; ADD 2X
	ASL	R1		; MULTIPLY BY 4
	ASL	R1		; MULTIPLY BY 8
	ADD	R0,R1		; ADD IN NEW DIGIT
	MOV	R1,D.DECN	; STORE IN DECIMAL NUMBER
	INC	R2		; R2 HAS NUMERIC FLAG
	BR	D.PRI1		;   AND TRY AGAIN
D.PRI2:	MOV	#'U,R0		; UNDEFINED MESSAGE
	BR	D.ERRO		; ERROR OUTPUT
D.PRI3:	CMPB	R0,#'.		; DOT FOUND?
	BEQ	D.PRI7		; BRANCH IF SO
	CLR	R1		; BASE OF CHARACTER TABLE
D.PRI4:	CMPB	D.LGCH(R1),R0	; MATCH?
	BEQ	D.PRI5		; YES
	INC	R1		; NEXT CHARACTER
	CMP	R1,#D.CLGT	; ANY MORE?
	BLT	D.PRI4		; LOOP IF SO
D.PRI6:	TST	R4		; NUMBER ALREADY?
	BNE	D.ERR		; ERROR TO START SYMBOL
	JSR	PC,D.PTSM	; PUT SYMBOL IN D.SYM
	BR	D.PRI1		; DECODE MORE CHARACTERS
D.PRI7:	TST	R2		; NUMBER BEING TYPED?
	BEQ	D.PRI6		; BRANCH IF NOT
	INCB	D.USED		; IT IS, MAKE IT DECIMAL
	BR	D.PRI1		; CONTINUE SCANNING
D.PRI5:	TSTB	D.ALTF		; ALTMODE FOUND?
	BNE	D.PRI8		; YES, DO IT
	CMP	R1,#D.LETR	; IS IT A LETTER?
	BGE	D.PRI6		; YES
D.PRI8:	CMPB	#' ,D.SYM	; ANY SYMBOL?
	BEQ	D.PRIB		; NO, RETURN
	CMP	#". ,D.SYM	; IS SYMBOL A DOT?
	BNE	D.PRI9		; BRANCH IF NOT
	MOV	D.DOT,R4	; USE VALUE OF D.DOT
	INC	R2		; NOTE THAT IT IS A NUMBER
	BR	D.PRIB		; DO THE REST
D.PRI9:	MOV	#D.SYM,R0	; ADDRESS OF SYMBOL
	JSR	PC,D.GTAD	; GET ADDRESS
	CMP	R1,#D.COLO	; COLON?
	BEQ	D.PRIC		; RETURN IF SO
	TST	R0		; CHECK SYMBOL ADDRESS
	BEQ	D.PRID		; BRANCH IF NOT AN ADDRESS
	MOV	(R0),R4		; GET SYMBOL VALUE
D.PRIA:	INC	R2		; MARK R2 AS A NUMBER
D.PRIB:	TSTB	D.USED		; USE DECIMAL NUMBER?
	BEQ	D.PRIC		; BRANCH IF NOT
	MOV	D.DECN,R4	; USE DECIMAL NUMBER
D.PRIC:	RTS	PC		; RETURN
D.PRID:	MOV	#D.COUS,R0	; ADDRESS OF OFFSET TABLE
D.PRIE:	CMP	R0,#D.ECNT	; END OF LIST?
	BHIS	D.PRI2		; YES, LOSE
	MOV	#D.SYM,R5	; SCAN THE SYMBOL
	MOV	(R0)+,R3	; GET OFFSET OF CHARACTERS
	BIC	#177400,R3	; TURN OFF EXTRA CRUFT
	CMPB	R3,(R0)		; NULL STRING?
	BEQ	D.PRIE		; YES, IGNORE IT
D.PRIF:	CMPB	D.STRS(R3),(R5)+; IS IT A CHARACTER MATCH?
	BNE	D.PRIE		; BRANCH IF NOT
	INC	R3		; NEXT CHARACTER
	CMPB	R3,(R0)		; END OF STRING?
	BNE	D.PRIF		; BRANCH IF NOT
	MOV	D.TOPS-D.COUS-2(R0),R4	;GET THE INSTRUCTION-1
	MOVB	-1(R0),R3	; GET LEGALITY BYTE
	CMPB	R3,#10		; IS IT A CONDITION CODE SET/CLEAR?
	BEQ	D.PRIK		; MAY BE
	INC	R4		; FIX INSTRUCTION
D.PRIG:	CMPB	#' ,(R5)	; BLANK AT END OF SYMBOL?
	BNE	D.PRII		; NO, HOW ABOUT "B"?
	BIC	#177774,R3	; STRIP TO MACHINE TYPE
	CMPB	R3,D.MACH	; VALID ON THIS MACHINE?
	BGT	D.PRI2		; UNDEFINED SYMBOL
D.PRIH:	MOVB	-(R0),R3	; RE-FETCH LEGALITY BYTE
	CMP	R1,#D.SPAC	; IS INSTRUCTION TERMINATED WITH SPACE?
	BNE	D.PRIA		; DON'T GET OPERANDS IF NOT
	MOV	#-2,R2		; MARK INSTRUCTION
	BR	D.PRIA		; ALL DONE
D.PRII:	CMPB	#'B,(R5)+	; BYTE INSTRUCTION MUST TERMINATE WITH "B"
	BNE	D.PRIE		; NOT AN INSTRUCTION
	TSTB	R3		; TEST LEGALITY BYTE
	BPL	D.PRIE		; NO
	ADD	#100000,R4	; ADD IN BYTE OFFSET
	BCC	D.PRIG		; AND CONTINUE, UNLESS THAT WAS A SECOND "B"
	BR	D.PRIE		; IN WHICH CASE WE LOSE

D.PRIJ:	BITB	(SP),R4		; BIT ALREADY ON?
	BNE	D.PRIN		; YES, LOSE
	BISB	(SP),R4		; SET IT
	CMPB	(SP)+,(R5)+	; BUMP SP BY 2, R5 BY 1
	CMPB	#' ,(R5)	; SPACE YET?
	BEQ	D.PRIH		; YES, ALL DONE.
D.PRIK:	MOVB	#10,-(SP)	; SET UP MAGIC BIT
	MOV	#D.NZVC+4,R3	; CHARACTER POINTER
D.PRIL:	CMPB	(R5),-(R3)	; MATCH?
	BEQ	D.PRIJ		; BRANCH IF SO
	ASRB	(SP)		; MOVE BIT
	BNE	D.PRIL		; AND LOOP
D.PRIN:	TSTB	(SP)+
	BR	D.PRIE		; ELSE NOT THE RIGHT INSTRUCTION
; ROUTINES TO HANDLE THE SYMBOL TABLE

D.GTAD:	MOV	R0,-(SP)	; SAVE CHARACTER ADDRESS
	JSR	PC,D.RD50	; CONVERT FIRST 3 TO RAD50
	MOV	R0,D.RAD1	; SAVE VALUE
	MOV	(SP)+,R0	; GET CHARACTER ADDRESS
	ADD	#3,R0		; POINT TO LAST 3 CHARACTERS
	JSR	PC,D.RD50	; CONVERT TO RAD50
	MOV	R0,D.RAD2	; STORE IT AWAY
D.GTAC:	MOV	#D.SYMA-2,R0	; ADDRESS OF SYMBOL TABLE
D.GTA2:	TST	(R0)+		; BUMP R0 BY 2
	CMP	(R0)+,(R0)	; BUMP R0 BY 2 MORE, CHECK IF END OF TABLE
	BNE	D.GTA6
	TST	(R0)		; WERE BOTH SYMBOL HALVES 0?
	BNE	D.GTA6		; NO, KEEP LOOKING
	CLR	R0		; NOT FOUND...MARK RETURN REGISTER
	RTS	PC		; RETURN
D.GTA6:	CMP	D.RAD2,(R0)+	; DO SECOND THREE CHARACTERS MATCH?
	BNE	D.GTA2		; NO, GO TO NEXT SYMBOL
	CMP	-4(R0),D.RAD1	; YES, HOW ABOUT THE FIRST THREE?
	BNE	D.GTA2		; NO, GO TO NEXT SYMBOL
	RTS	PC		; RETURN

D.GTSM:	CLR	-(SP)		; SPACE FOR TEMPORARIES
	MOV	D.FENC,R2	; FIND CLOSEST SYMBOL <= R0
	MOV	D.RFNL,R1	; WHICH IS ALSO >= R0-D.RFNL
D.GTS1:	CMP	(R2)+,(R2)+	; SKIP OVER THE NAME
	BEQ	D.GTS3
D.GTS2:	MOV	R0,R3		; SET A TEMPORARY
	SUB	(R2)+,R3	; OBTAIN DIFERENCE
	BLO	D.GTS1		; IF SYMBOL HIGHER THAN R0, NO GO
	SUB	R1,R3		; ARE WE CLOSER THAN BEFORE?
	BHI	D.GTS1		; NO, FURTHER
	MOV	R2,(SP)		; SAVE POINTER TO SYMBOL
	ADD	R3,R1		; SAVE DIFFERENCE
	BR	D.GTS1		; AND LOOK FOR ONE CLOSER
D.GTS3:	TST	-2(R2)		; AT END OF TABLE?
	BNE	D.GTS2		; NO, KEEP GOING
	MOV	(SP)+,R1	; GET SYMBOL PTR
	BEQ	D.GTS4		; BRANCH IF NOT FOUND.
	CMP	-(R1),#400	; IGNORE SMALL SYMBOLS
	BLO	D.GTS4
	SUB	(R1),R0		; RECOMPUTE DIFFERENCE
	MOV	R0,-(SP)	; SAVE DIFFERENCE
	MOV	-(R1),-(SP)	; GET LAST THREE CHARACTERS
	MOV	-(R1),R0	; GET FIRST THREE
	MOV	#D.SYM,R1	; ADDRESS TO PUT CHARACTERS
	JSR	PC,D.CHAR	; CONVERT TO ASCII
	MOV	(SP)+,R0	; GET FIRST RAD50 WORD
	JSR	PC,D.CHAR	; CONVERT TO ASCII
	MOV	(SP)+,R0	; RESTORE DIFFERENCE
	MOV	#D.SYM,R1	; POINT TO CHARACTERS
	RTS	PC		; RETURN
D.GTS4:	CLR	R1		; NOT FOUND...MARK IT SO
	RTS	PC		; RETURN
; ROUTINE TO GET AN EXPRESSION (VALUE IN R4, FLAG IN R2, TERMINATOR IN R1)

D.CEXP:	INCB	D.INPA		; NOT IN INSTRUCTION
	CLR	D.OFST		; START OUT FRESH
D.EXPR:	MOV	#D.ADD,D.OPER	; INITIAL FUNCTION
D.EXP7:	JSR	PC,D.PRIM	; GET PRIMARY EXPRESSION
	TST	R2		; INSTRUCTION?
	BMI	D.EXP1		; EXIT IF SO
	CMP	R1,#D.OPAR	; OPEN PARENTHESIS OR OPERATOR?
	BLT	D.EXP1		; BRANCH IF NEITHER
	BEQ	D.EXP2		; BRANCH IF OPEN PARENTHESIS
	CMP	R1,#D.CPAR	; CLOSE PARENTHESIS OR OPERATOR?
	BLT	D.EXP3		; BRANCH IF OPERATOR
	BEQ	D.EXP4		; BRANCH IF CLOSE PARENTHESIS
D.EXP1:	TSTB	D.LEVL		; TERMINATOR FOUND...AT UPPER LEVEL?
	BEQ	D.EXP5		; BRANCH IF SO
	BR	D.ERRD		; ERROR
D.EXP2:	TSTB	D.INPA		; IN AN INSTRUCTION TYPE-IN?
	BNE	D.EXP5		; BRANCH IF SO (INSTRUCTION FORMAT)
	INCB	D.LEVL		; GO DOWN TO NEXT PARENTHESIS LEVEL
	MOV	D.OFST,-(SP)	; SAVE TALLY
	MOV	D.OPER,-(SP)	; SAVE OPERATION
	CLR	D.OFST		; CLEAR TALLY
	JSR	PC,D.EXPR	; RECURSION!
	MOV	(SP)+,D.OPER	; RESTORE OPERATION
	MOV	(SP)+,D.OFST	; RESTORE TALLY
	JSR	PC,@D.OPER	; COMBINE THEM
	BR	D.EXPR		; LOOP
D.EXP4:	DECB	D.LEVL		; UP TO HIGHER PARENTHESIS LEVEL
	BMI	D.ERRD		; ERROR IF NONE HIGHER
D.EXP5:	JSR	PC,@D.OPER	; DO OPERATION
	MOV	D.OFST,R4	; GET TALLY AS RETURN PARAMETER
	RTS	PC		; RETURN (POSSIBLY TO SELF)
D.EXP3:	JSR	PC,@D.OPER	; DO OPERATION
	ASL	R1		; AND GET
	MOV	D.LGDR(R1),D.OPER ;   THE NEXT
	BR	D.EXP7		; LOOP
; ROUTINE TO HANDLE PARAMETERS FOR INSTRUCTION TYPE-IN

D.GETI:	ASR	R3		; PARAMETER CODE
	BIC	#177741,R3	; MASK OUT OTHER BITS
	MOV	R4,-(SP)	; SAVE OPERATION MASK
	JSR	PC,@D.PARG(R3)	; GET PARAMETERS
	BIS	(SP)+,R4	; PUT OPERATION MASK INTO OPERANDS
	MOV	#1,R2		; MARK A GOOD NUMBER
	RTS	PC		; RETURN

D.GR:	JSR	PC,D.PRIM	; GET PRIMARY
D.REDR:	SUB	#D.UR0,R4	; GET REGISTER ADDRESS
	ASR	R4		; MAKE INTEGER FROM ADDRESS
	BIT	#177770,R4	; ANY HIGH BITS ON?
	BNE	D.ERRD		; ERROR IF NOT A REGISTER
D.NONE:	RTS	PC		; RETURN

D.GGET:	MOV	R0,-(SP)	; SAVE WHAT MUST BE READ
D.GGE2:	JSR	PC,D.GET	; GET LETTER
	CMP	R0,(SP)		; EQUAL?
	BEQ	D.GGE1		; YES, RETURN
D.ERRD:	JMP	D.ERR		; ERROR
D.GGE1:	TST	(SP)+		; FIX STACK
	RTS	PC		; RETURN

D.PSAV:	MOV	(SP),-(SP)	; PUSH RETURN ADDRESS DOWN
	SWAB	R4		; MOVE
	ASR	R4		;  TO
	ASR	R4		;   HIGH POSITION
	MOV	R4,2(SP)	; PUT PARAMETERS IN
	CMP	R1,#D.COMM	; COMMA IN-BETWEEN?
	BNE	D.ERRD		; ERROR IF NOT
	RTS	PC		; RETURN

D.DISP:	JSR	PC,D.CEXP	; GET EXPRESSION
	SUB	D.DOT,R4	; COMPUTE OFFSET
	ASR	R4		; SHIFT
	DEC	R4		; POINTS TO PROPER WORD
	BIC	#177400,R4	; CLEAR HIGH BITS
	RTS	PC		; RETURN

D.GRNN:	JSR	PC,D.GR		; GET REGISTER
	JSR	PC,D.PSAV	; SAVE PARAMETERS
	JSR	PC,D.DISP	; GET ADDRESS
	MOVB	R4,R4		;MAKE IT A FULLWORD
	NEG	R4		;NEGATE IT
	BIT	#^C77,R4	;POSITIVE & 6 BITS?
	BNE	D.ERRD		;BR IF OUT OF RANGE
D.GGE3:	BIS	(SP)+,R4	; ADD IN REGISTER
	RTS	PC		; RETURN
D.GSD:	JSR	PC,D.GDD	; GET 6-BIT OPERAND
D.GGE4:	JSR	PC,D.PSAV	; SAVE PARAMETER
	JSR	PC,D.GDD	; GET OTHER PARAMETER
	BR	D.GGE3		; DO THE REST
D.GRSS:	JSR	PC,D.GR		; GET REGISTER
	BR	D.GGE4		; DO THE REST
D.GDDR:	JSR	PC,D.GDD	; GET 6-BIT-OPERAND
	MOV	R4,-(SP)	; SAVE OPERAND
	JSR	PC,D.GR		; GET REGISTER
	SWAB	R4		; SHIFT
	ASR	R4		;  INTO
	ASR	R4		;   HIGH PLACE
	BR	D.GGE3		; DO THE REST

D.NEXP:	MOV	D.CADC,R0	; GET CAD COPY
	TST	(R0)+		; BUMP TO NEXT
	MOV	R0,D.CADC	; RESTORE NEW VALUE
	TST	(R0)+		; INCREMENT AGAIN
	RTS	PC		; RETURN

D.GDD:	CLR	R2		; NO PARAMETERS YET
	JSR	PC,D.CEXP	; GET EXPRESSION
	CMP	R1,#D.OPAR	; OPEN PARENTHESIS?
	BEQ	D.G02		; BRANCH IF SO
	CMP	R1,#D.HASH	; HASH MARK?
	BEQ	D.G05		; BRANCH IF SO
	BLO	D.G03		; BRANCH IF AT-SIGN
	CMP	R4,#D.UR0	; REGISTER?
	BLO	D.NOTR		; BRANCH IF NOT
	CMP	R4,#D.UR7	; REGISTER?
	BHI	D.NOTR		; BRANCH IF NOT
	SUB	#D.UR0,R4	; NORMALIZE
	ASR	R4
	RTS	PC		; RETURN
D.NOTR:	JSR	PC,D.NEXP	; POINT TO NEXT PARAMETER
	MOV	R0,-(SP)	; SAVE RELOCATION
	SUB	D.CAD,R0	; GET PARAMETER OFFSET
	MOV	(SP)+,D.PARO-4(R0) ; PUT IN OFFSET
	MOV	R4,D.PARS-4(R0)	; PUT VALUE IN
	MOV	#67,R4		; RELATIVE PC ADDRESSING
	RTS	PC		; DONE
D.G05:	JSR	PC,D.CEXP	; GET EXPRESSION
D.G014:	JSR	PC,D.NEXP	; NEXT PARAMETER
	SUB	D.CAD,R0	; GET PARAMETER OFFSET
	CLR	D.PARO-4(R0)	; NO RELOCATION
	MOV	R4,D.PARS-4(R0)	; PUT VALUE IN
	MOV	#27,R4		; IMMEDIATE ADDRESSING
	RTS	PC		; RETURN
D.G02:	TST	R2		; "(" FOUND, ANY OFFSET?
	BNE	D.G013		; BRANCH IF SO (INDEX ADDRESSING)
	CMP	D.OPER,#D.SUBT	; "-(R)" ?
	BNE	D.G016		; BRANCH IF NOT
	JSR	PC,D.GR		; GET REGISTER
	ADD	#40,R4		; ADD IN AUTO-DECR OFFSET
	BR	D.G09		; SKIP TO COMMAND AND RETURN
D.G016:	JSR	PC,D.GR		; GET REGISTER..."(R)" OR "(R)+"
	JSR	PC,D.G09	; SKIP TO NEXT PARAMETER
	CMP	R1,#D.ADDS	; PLUS SIGN?
	BNE	D.G012		; BRANCH IF NOT
	ADD	#20,R4		; ADD IN AUTO-INCR OFFSET
	BR	D.G09		; SKIP TO COMMAND AND RETURN
D.G013:	JSR	PC,D.G014	; PUT PARAMETER IN
	JSR	PC,D.GR		; GET REGISTER
	ADD	#60,R4		; ADD IN INDEX OFFSET
	BR	D.G09		; SKIP TO COMMAND AND RETURN
D.G03:	CLR	R2		; "@" FOUND, MARK NO NUMBER FOUND YET
	JSR	PC,D.CEXP	; AN "@" WAS FOUND, LOOK TO NEXT
	CMP	R1,#D.HASH	; "@#" MEANS ABSOLUTE ADDRESSING
	BEQ	D.G06		; BRANCH IF SO
	CMP	R1,#D.OPAR	; COULD BE "@(" OR "@X("
	BEQ	D.G07		; BRANCH IF EITHER
	CMP	R4,#D.UR0	; IS IT @R?
	BLO	D.G08		; BRANCH IF NOT
	CMP	R4,#D.UR7	; TEST UPPER RANGE
	BHI	D.G08		; BRANCH IF NOT
	JSR	PC,D.REDR	; REDUCE TO REGISTER NUMBER
D.G012:	ADD	#10,R4		; ADD IN REG-DEFERRED OFFSET
	RTS	PC		; THATS ALL...RETURN
D.G08:	JSR	PC,D.NOTR	; PERFORM NORMAL RELOCATION
	MOV	#77,R4		; MARK RELATIVE DEFERRED ADDRESSING
	RTS	PC		; RETURN
D.G07:	TST	R2		; ANY NUMBER THERE?
	BEQ	D.G010		; BRANCH IF "@("
	JSR	PC,D.G014	; GET OFFSET INTO PARAMETER
	JSR	PC,D.GR		; NOW GET REGISTER
	ADD	#70,R4		; ADD IN INDEX DEFERRED OFFSET
D.G09:	MOV	R4,-(SP)	; SAVE VALUE
	JSR	PC,D.PRIM	; SKIP TO NEXT COMMAND
	MOV	(SP)+,R4	; RESTORE VALUE
	RTS	PC		; RETURN
D.G010:	CMP	D.OPER,#D.SUBT	; "@-(" ?
	BNE	D.G015		; BRANCH IF NOT
	JSR	PC,D.GR		; GET REGISTER
	ADD	#50,R4		; ADD IN AUTO-DECR DEFERRED OFFSET
	BR	D.G09		; SKIP TO COMMAND AND RETURN
D.G015:	JSR	PC,D.GR		; GET REGISTER
	MOV	#'+,R0		; FORM IS "@(R)+"
	JSR	PC,D.GGET	; GET THE PLUS
	ADD	#30,R4		; ADD IN AUTO-INCR DEFERRED OFFSET
	BR	D.G09		; SKIP TO COMMAND AND RETURN
D.G06:	JSR	PC,D.G05	; GET ABSOLUTE ADDRESS
	MOV	#37,R4		; MARK ABSOLUTE MODE
	RTS	PC		; DONE
D.GNUM:	JMP	D.PRIM		; GET NUMBER AND RETURN
; SYMBOL MANIPULATION SUBROUTINES

D.PTSM:	MOV	D.POS,R1	; GET POSITION ADDRESS
	CMP	R1,#D.SYM+D.SYML; NO MORE ROOM?
	BHIS	D.PTS1		; EXIT IF SO
	MOVB	R0,(R1)+	; PUT CHARACTER IN
	MOV	R1,D.POS	; RESTORE POINTER
D.PTS1:	RTS	PC		; RETURN

D.CLSM:	MOV	#D.SYM+D.SYML,R0
D.CLS3:	MOVB	#' ,-(R0)
	CMP	R0,#D.SYM
	BHI	D.CLS3
	MOV	R0,D.POS
	RTS	PC		; RETURN

; ADDITION, SUBTRACTION, MULTIPLICATION, DIVISION FOR DECODER

D.ADD:	ADD	R4,D.OFST	; ADD OPERANDS
	RTS	PC		; RETURN
D.SUBT:	SUB	R4,D.OFST	; SUBTRACT OPERANDS
	RTS	PC		; RETURN
D.MULT:	CLR	R0		; MULTIPLY THEM
	MOV	#16.,-(SP)	; LOOPER
D.MUL1:	ASR	R4		; GET BOTTOM BIT
	BCC	D.MUL2		; SKIP IF OFF
	ADD	D.OFST,R0	; ADD IN OPERAND
D.MUL2:	ASL	D.OFST		; SHIFT OPERAND
	DEC	(SP)		; MORE TO LOOP?
	BGT	D.MUL1		; LOOP IF SO
	MOV	R0,D.OFST	; RESULT IN D.OFST
	TST	(SP)+		; FIX STACK
	RTS	PC		; RETURN
D.DIV:	MOV	R1,-(SP)	; SAVE R1
	MOV	D.OFST,R0	; GET OPERAND
	MOV	R4,R2		; GET OTHER OPERAND
	JSR	PC,D.DIVD	; DIVIDE THEM
	MOV	R0,D.OFST	; GET RESULT
	MOV	(SP)+,R1	; RESTORE R1
	RTS	PC		; RETURN

; MANIPULATION OF THE SYMBOL TABLE

D.SWAP:	MOV	#3,R2		; COUNTER
D.SWA1:	MOV	-(R1),-(SP)	; GET WORD
	MOV	(R0),(R1)	; PUT OTHER WORD IN
	MOV	(SP)+,(R0)	; AND FINISH SWAP
	TST	-(R0)		; MOVE WORD
	DEC	R2		; LOOPER
	BGT	D.SWA1		; LOOP IF MORE
	RTS	PC		; RETURN
; PROCESS : - DEFINE SYMBOL

D.COLN:	CMPB	D.SYM,#' 	; NULL SYMBOL?
	BEQ	D.ERRB		; ERROR IF SO
	MOV	D.DOT,R4	; ASSUME DOT ADDRESS
	TSTB	D.FWAF		; REAL VALUE GIVEN?
	BEQ	D.COL1		; BRANCH IF NOT
	MOV	D.FWA,R4	; GET REAL VALUE
D.COL1:	TST	R0		; IN SYMBOL TABLE?
	BNE	D.COL2		; BRANCH IF SO
	MOV	D.RAD1,-(SP)	; SAVE RAD50 OF NAME
	MOV	D.RAD2,-(SP)	; BOTH HALVES
	MOV	#-1,D.RAD1	; ASSUME NULL RAD50 LABEL
	MOV	#-1,D.RAD2	; IN BOTH HALVES
	JSR	PC,D.GTAC	; LOOK IT UP
	TST	R0		; FOUND?
	BEQ	D.ERRB		; ERROR IF NOT
	MOV	(SP)+,-(R0)	; FILL LABEL IN
	MOV	(SP)+,-(R0)	;  BY SETTING BOTH WORDS
	CMP	(R0)+,(R0)+	; NOW FIX POSITION
D.COL2:	MOV	R4,(R0)		; AND SET VALUE
	MOV	R0,D.LASC	; SET LAST COLONED WORD
	MOV	D.FENC,R1	; GET FENCE
	CMP	R0,R1		; BEHIND FENCE?
	BHI	D.COL5		; DONE IF NOT
	JSR	PC,D.SWAP	; SWAP SYMBOLS
	MOV	R1,D.FENC	; STORE IN FENCE
D.COL5:	RTS	PC		; RETURN
D.ERRB:	JMP	D.ERR		; ERROR

; PROCESS D - DELETE LAST COLONED SYMBOL

D.DELE:	MOV	D.LASC,R0	; GET LAST COLONED SYMBOL
	BEQ	D.ERRB		; ERROR IF NONE
	CLR	D.LASC		; LAST TIME TO COLON IT
	BR	D.KIL3		; NOW KILL IT

; PROCESS K - KILL SYMBOL

D.KILL:	JSR	PC,D.GTAC	; GET ADDRESS OF SYMBOL
	TST	R0		; ANY SYMBOL?
	BEQ	D.ERRB		; ERROR IF NOT
	CMPB	D.ALTF,#1	; HOW MANY ALTMODES?
	BGT	D.KIL1		; BRANCH IF 2
D.KIL3:	MOV	D.FENC,R1	; GET FENCE
	CMP	R0,R1		; SYMBOL BEHIND FENCE?
	BLO	D.KIL4		; BRANCH IF ALREADY KILLED
	ADD	#6,R1		; PUSH UP FENCE
	MOV	R1,D.FENC	; AND STORE IT
	JMP	D.SWAP		; SWAP SYMBOLS AND RETURN
D.KIL1:	CLR	(R0)		; CLEAR ADDRESS
	MOV	#-1,-(R0)	; PUT IN NULL SYMBOL
	MOV	#-1,-(R0)	; IN BOTH WORDS
D.KIL4:	RTS	PC		; RETURN
; PROCESS ALTMODE

D.ALTM:	TSTB	D.ALTF		; ALREADY AN ALTMODE TYPED?
	BNE	D.ALT1		; BRANCH IF SO
	MOV	R2,D.SVR2	; AN ALTMODE HAS BEEN RECEIVED
	MOV	R4,D.SVR4	; NUMERIC FLAG TO D.SVR2, CONTENTS TO D.SVR4
D.ALT1:	CLR	R2		; NO ARGS TYPED YET
	CLR	D.OFST		; CLEAR OFFSET
	INCB	D.ALTF		; COUNT NUMBER OF ALTMODES
	JMP	D.DCD1		; RETURN

; PROCESS / - OPEN WORD

D.WRD:	MOV	D.CURM,D.OMOD	; TEMP COPY OF ROUTINE ADDRESS
D.WRD1:	TST	R2		; NUMBER THERE?
	BNE	D.WRD3		; BRANCH IF SO
D.WRD4:	MOV	D.LASV,D.CAD	; SET LAST ADDRESS
	BR	D.SEMI		; DO IT
D.WRD3:	MOV	R4,D.DOT	; SET DOT
D.WRD5:	MOV	D.DOT,D.CAD	; SET CURRENT ADDRESS

; PROCESS ; - RETYPE WORD

D.SEMI:	JMP	@D.OMOD		; TYPE WORD AND RETURN

; PROCESS <TAB> - OPEN INDIRECT

D.ORAB:	JSR	PC,D.CLSE	; CLOSE WORD
	MOV	D.LASV,D.DOT	; INDIRECT REFERENCE
	BR	D.OP2		; OPEN IT AND RETURN

; PROCESS ! - OPEN WORD SILENTLY

D.EXCL:	MOV	#D.RTS,D.OMOD	; NULL ROUTINE FOR TYPING
	BR	D.WRD1		; OPEN WORD

; PROCESS \ - OPEN LAST REFERENCED WORD

D.BKSL:	TST	R2		; ANY PARAMETER?
	BEQ	D.WRD4		; BRANCH IF NOT
	JSR	PC,D.CLSE	; CLOSE WORD
	BR	D.WRD4		; OPEN INDIRECT
; PROCESS <LF> - OPEN NEXT WORD

D.OP1:	JSR	PC,D.CLSE	; CLOSE WORD
	ADD	D.BW,D.DOT	; ADD IN BYTE/WORD INCREMENT
	ADD	D.LFIN,D.DOT	; ADD IN LINE-FEED INCREMENT
D.OP2:	JSR	PC,D.CRLF	; TYPE CRLF
D.OP3:	MOV	D.DOT,R0	; GET WORD
	JSR	PC,D.RFND	; TYPE ADDRESS
	MOV	#'/,R0		; SLASH
	JSR	PC,D.TYPE	; TYPE IT
	BR	D.WRD5		; TYPE CONTENTS

; PROCESS [ - OPEN WORD AS NUMERIC

D.OPBR:	MOV	#D.CADV,D.OMOD	; NUMBER ROUTINE
	BR	D.WRD1		; DO ROUTINE

; PROCESS ] - OPEN WORD AS INSTRUCTION

D.CLBR:	MOV	#D.INST,D.OMOD	; INSTRUCTION ROUTINE
	BR	D.WRD1		; DO IT

; PROCESS ^ - OPEN PREVIOUS WORD

D.BACK:	JSR	PC,D.CLSE	; CLOSE WORD
	SUB	D.BW,D.DOT	; SUBTRACT BYTE/WORD INCREMENT
	BR	D.OP2		; OPEN WORD

; PROCESS _ - TYPE WORD SYMBOLICALLY

D.ORPC:	MOV	D.LASW,R0	; GET LAST TYPED WORD
	CLR	D.LFIN		; NO LINE-FEED INCREMENT
	TSTB	D.ALTF		; IS IT AN $_ ?
	BEQ	D.ORP1		; BRANCH IF NOT
	JMP	D.RFND		; TYPE SYMBOLICALLY AND RETURN
D.ORP1:	JMP	D.INST		; TYPE INSTRUCTION AND RETURN

; PROCESS = - TYPE WORD AS NUMBER

D.EQAL:	MOV	D.LASW,R0	; GET LAST TYPED WORD
	CLR	D.LFIN		; NO LINE-FEED INCREMENT
	JMP	D.TYPN		; TYPE AS A NUMBER
; PROCESS , - COMMA PARAMETER

D.DCOM:	TST	R2		; ANY PARAMETER?
	BEQ	D.FWA1		; BRANCH IF NOT
	MOV	R4,D.COMA	; PUT IN PARAMETER AREA
	BR	D.FWA1		; RETURN

; PROCESS < - STORE FIRST WORD ADDRESS FOR SEARCH

D.FWAS:	MOV	R4,D.FWA	; SET FIRST WORD
	INCB	D.FWAF		; MARK FIRST WORD FOUND
D.FWA1:	JMP	D.DCD2		; RETURN

; PROCESS Z - ZERO CORE

D.ZERO:	MOV	D.FWA,R0	; FIRST WORD
D.ZER1:	CMP	R0,D.SVR4	; AT LAST WORD?
	BHI	D.ONE1		; DONE IF SO
	CLR	(R0)+		; CLEAR WORD
	BR	D.ZER1		; LOOP

; PROCESS U - SECOND SET OF INSTRUCTIONS

D.SNGL:	CLR	R5		; OFFSET
	JSR	PC,D.GET	; GET CHARACTER
D.SNG2:	CMPB	D.UTAB(R5),R0	; MATCH?
	BNE	D.SNG1		; NO
	ASL	R5		; MULTIPLY BY 2
	JMP	@D.UADD(R5)	; DO THIS ROUTINE
D.SNG1:	INC	R5		; NEXT CHARACTER
	CMP	R5,#D.ENUT	; END OF LIST?
	BLT	D.SNG2		; LOOP IF NOT
D.ERRE:	JMP	D.ERR		; RETURN

; PROCESS UT - SET SINGLE INSTRUCTION

D.ONES:	MOVB	R4,D.S		; SET INDICATOR
	CLR	D.CT		; SET FOR AUTOMATIC PROCEDE
	CMPB	D.ALTF,#1	; TWO ALTMODES?
	BGT	D.ONE2		; FINISH UP IF SO
	INC	D.CT		; SET NORMAL PROCEDE
D.ONE2:	MOV	D.SVR4,D.OPEN	; SET ADDRESS TO OPEN AT BREAK
D.ONE1:	RTS	PC		; RETURN

; PROCESS UW - SET RFND LIMIT

D.WULF:	MOV	D.SVR4,D.RFNL	; SET LIMIT
	RTS	PC		; RETURN

; PROCESS UG - RETURN USER DISPLAY

	.IF	DF,D.GDP
D.GRAP:	 TRAP	144
	 MOV	#104544,D.SAV9	; UG! SELF MODIFYING-CODE
	 RTS	PC
	.ENDC
; PROCESS E, N AND W - SEARCHES

D.EFF:	MOV	#1,R1		; SET EFFECTIVE SEARCH
	BR	D.WDS		; DO SEARCH
D.NSCH:	MOV	#-1,R1		; SET NON-SEARCH
	BR	D.WDS		; DO SEARCH
D.WSCH:	CLR	R1		; SET WORD SEARCH
D.WDS:	TST	D.SVR2		; NUMBER TO SEARCH FOR?
	BEQ	D.ERRE		; ERROR IF NOT
	MOV	D.CAD,-(SP)	; THIS IS "MOST RECENT VALUE" OF D.CAD
	MOV	D.FWA,R2	; SET ORIGIN
D.WDS2:	.IF	NDF,D.KSR
	 TSTB	@#D.RCSR	; CHARACTER TYPED?
	 BMI	D.WDS6		; BRANCH IF SO
	.ENDC
	.IF	DF,D.KSR
	 JSR	PC,D.POLL	; CHECK FOR TYPED CHARACTER
	 CMP	D.INPU,D.OUTP	; ANY CHARACTERS IN BUFFER?
	 BNE	D.WDS6
	.ENDC
	CMP	R2,D.LWA	; IS THE SEARCH ALL DONE?
	BHI	D.WDS6		;  YES
	MOV	D.SVR4,R5	; GET NUMBER TO SEARCH FOR
	MOV	D.MASK,R4	; GET MASK
	COM	R4		; COMPLEMENT IT
	MOV	(R2),R0		; GET OBJECT
	MOV	R2,D.CAD	; THIS IS CURRENT ADDRESS
	BIC	R4,R0		; TURN OFF BITS NOT BEING SEARCHED FOR
	BIC	R4,R5		; TURN OFF BITS NOT BEING SEARCHED FOR
	MOV	R1,-(SP)	; STORE AND TEST
	BMI	D.WDS5		; BRANCH IF NON-SEARCH
	BGT	D.WDS7		; BRANCH IF EFFECTIVE SEARCH
	CMP	R0,R5		; EQUALITY?
	BNE	D.WDS4		; RE-LOOP IF NO MATCH
D.WDS1:	JSR	PC,D.CRLF	; TYPE CRLF
	MOV	D.CAD,R0	; GET READY TO TYPE
	MOV	R0,2(SP)	; SET MOST RECENT VALUE OF D.CAD
	JSR	PC,D.RFND	; RELOCATE
	MOV	#'/,R0		; SLASH TO R0
	JSR	PC,D.TYPE	; TYPE IT
	JSR	PC,@D.CURM	; TYPE CONTENTS
D.WDS4:	MOV	(SP)+,R1	; RESTORE R1
	MOV	D.CAD,R2	; RESTORE R2
	TST	(R2)+		; INCREMENT TO NEXT CELL AND
	BR	D.WDS2		;    RETURN
D.WDS7:	MOV	#1,D.BOTH	; MARK NOTHING FOUND AND DON'T TYPE INSTRUCTION
	JSR	PC,D.INST	; "TYPE" THE INSTRUCTION
	DEC	D.BOTH		; ALLOW TYPEOUT AND TEST FOUND INDICATOR
D.WDS9:	BEQ	D.WDS4		; BRANCH IF NOT FOUND
	BR	D.WDS1		; BRANCH IF FOUND
D.WDS5:	CMP	R0,R5		; EQUALITY?
	BR	D.WDS9		; BRANCH TO DECIDE
D.WDS6:	MOV	(SP)+,D.CAD	; RESTORE MOST RECENT VALUE OF D.CAD
	RTS	PC		; RETURN
; PROCESS H - HALF WORD TYPEOUT

D.INHA:	MOV	#1,D.BW		; SET HALF WORD MODE

; PROCESS C - SET NUMERIC TYPEOUT

D.INNM:	MOV	#D.CADV,D.CURM	; SET NUMERIC MODE
D.INN3:	MOV	D.CURM,D.OMOD	; SET LF AND ^ TYPEOUT MODE
D.INN2:	CMPB	D.ALTF,#2	; TWO ALTMODES TYPED?
	BLT	D.CRE1		; RETURN IF NOT
	MOV	#D.CURM,R0	; ADDRESS OF TEMPORARY TABLE
	MOV	#D.PERM,R1	; ADDRESS OF PERMANENT TABLE

D.SWAM:	MOV	#4,R2		; SWAP MODES: WORD COUNTER IN R2
D.SWA2:	MOV	(R0)+,(R1)+	; MOVE A WORD
	DEC	R2		; DECREMENT COUNTER
	BGT	D.SWA2		; LOOP TILL DONE
	RTS	PC		; RETURN

; PROCESS T - TEXT TYPEOUT

D.INTX:	MOV	#D.ASCI,D.CURM	; DEFAULT TO ASCII
	CMP	R4,#5		; RAD50?
	BNE	D.INN3		; RETURN IF NOT
	MOV	#D.RADC,D.CURM	; RAD50
	BR	D.INM1		; RETURN

; PROCESS O - BYTE TYPEOUT

D.BYTE:	MOV	#D.PART,D.CURM	; IN BYTE TYPEOUT MODE
	MOV	D.DECN,D.SIZE	; SET BYTE SIZE
	BR	D.INM1		; RETURN

; PROCESS S - INSTRUCTION TYPEOUT

D.INMD:	MOV	#D.INST,D.CURM	; IN INSTRUCTION MODE
D.INM1:	MOV	#2,D.BW		; MUST BE FULLWORD MODE
	BR	D.INN3		; RETURN

; PROCESS A - ABSOLUTE ADDRESS TYPEOUT

D.ABS:	MOV	#1,D.IFMT	; SET ABSOLUTE ADDRESSING
	BR	D.INN2		; RETURN

; PROCESS R - SET RADIX

D.INRD:	TST	R2		; RADIX SPECIFIED?
	BEQ	D.INR1		; BRANCH IF NOT
	CMP	D.DECN,#2	; MUST BE GREATER THAN 1
	BLT	D.ERRC		; BRANCH IF NOT
	MOV	D.DECN,D.DVTB	; ALWAYS DECIMAL RADIX
	BR	D.INN2		; RETURN
D.INR1:	CLR	D.IFMT		; TURN ON RELATIVE ADDRESSING
	BR	D.INN2		; RETURN

; PROCESS <CR> - CLOSE WORD AND RESET PERMANENT MODES

D.CRET:	JSR	PC,D.CLSE	; CLOSE LOCATION
	MOV	#D.PERM,R0	; ADDRESS OF PERMANENT TABLE
	MOV	#D.CURM,R1	; ADDRESS OF TEMPORARY TABLE
	JSR	PC,D.SWAM	; SWAP MODES
	MOV	D.CURM,D.OMOD	; SET LF AND ^ TYPEOUT MODE
D.CRE1:	JMP	D.DCD0		; RETURN
; PROCESS > - STORE LAST WORD ADDRESS FOR SEARCH

D.LWAS:	MOV	R4,D.LWA	; SET LAST WORD
	TST	R2		; ANY WORD THERE?
	BNE	D.CRE1		; BRANCH IF NOT
	MOV	#DDT-2,D.LWA	; SET HIGH LAST WORD
	BR	D.CRE1		; RETURN

; PROCESS B - SET AND REMOVE BREAKPOINTS

D.BKPT:	TST	D.SVR2		; DID HE GIVE A FIRST ARG?
	BEQ	D.BKP9
	ASL	R4		; MULTIPLY NUMBER BY TWO
	MOV	D.SVR4,R5	; GET FIRST NUMBER
	BEQ	D.BKP4		; REMOVE BREAK IF FIRST ARG 0
	TST	(R5)		; VALID ADDRESS? NXM IF NOT
	TST	R4		; SPECIFIC CELL REQUESTED?
	BNE	D.BKP1		; JUMP IF SO
	MOV	#2,R4
D.BKP3:	MOV	D.BKTB-2(R4),R0	; IS THIS CELL FREE?
	BEQ	D.BKP2		; JUMP IF YES
	CMP	R0,R5		; IS BREAK ALREADY SET FOR THIS ADDRESS?
	BEQ	D.BKP2		; BRANCH IF YES
	TST	(R4)+		; INCREMENT BY TWO
	CMP	R4,#D.BKP*2	; ARE WE AT THE END OF OUR ROPE?
	BLOS	D.BKP3		; NO, KEEP LOOKING
D.BKP1:	CMP	R4,#D.BKP*2	; REQUESTED NUMBER TOO LARGE?
	BHI	D.ERRC		; ERROR IF TOO LARGE
D.BKP2:	MOV	R5,D.BKTB-2(R4)	; SET BREAKPOINT
	MOV	D.COMA,D.OPEN(R4) ; SET WORD TO OPEN AT BREAKPOINT
	CLR	D.CT(R4)	; SET CONTINUE COUNT
	CMPB	D.ALTF,#1	; TWO ALTMODES?
	BGT	D.BKP8		; BRANCH IF NOT
	INC	D.CT(R4)	; DO NOT SET AUTOMATIC PROCEDE
D.BKP8:	RTS	PC		; RETURN
D.BKP4:	TST	R2		; IF NO NUMBER WAS TYPED...
	BEQ	D.BKP6		; GO REMOVE ALL
	CMP	R4,#D.BKP*2	; WAS THE TYPED NUMBER VALID?
	BHI	D.ERRC		; JUMP IF NOT
	CLR	D.BKTB-2(R4)	; CLEAR BREAKPOINT
	RTS	PC		; RETURN
D.BKP5:	ASL	R4
D.BKP6:	MOV	#D.BKTB+<D.BKP*2>,R4
D.BKP7:	CLR	-(R4)
	CMP	R4,#D.BKTB
	BHI	D.BKP7
	RTS	PC		; RETURN
D.BKP9:	TST	R2
	BEQ	D.BKP5
	DEC	R4
	CMP	R4,#D.BKP	; WAS THE TYPED NUMBER VALID?
	BHIS	D.ERRC		; JUMP IF NOT
	ADD	#D.BKTB-2+1,R4
	BR	D.MAS2
D.ERRC:	JMP	D.ERR		; INTERMEDIATE HELP
; PROCESS M - TYPE AND SET MASK

D.MAST:	MOV	#D.MASK,-(SP)	; GET MASK
	TST	D.SVR2		; NUMBER THERE?
	BNE	D.MAS3		; BRANCH IF SO
D.MAS1:	MOV	(SP)+,R4	; ADDRESS TO OPEN
D.MAS2:	JSR	PC,@D.OPER	; COMBINE VALUE WITH CURRENT EXPRESSION
	INC	R2		; MARK A TYPED NUMBER
	JMP	D.DCD3		; CONTINUE SCANNING
D.MAS3:	MOV	D.SVR4,@(SP)+	; SET MASK
	RTS	PC		; RETURN

; PROCESS V - GET CONTENTS OF D.DOT SWABBED

D.ALTV:	MOV	@D.DOT,R4	; CONTENTS OF WORD
	SWAB	R4		; SWAB IT
	BR	D.MAS2		; RETURN

; PROCESS Q - GET CONTENTS OF D.DOT

D.ALTQ:	MOV	@D.DOT,R4	; CONTENTS OF WORD
	BR	D.MAS2		; RETURN

; PROCESS I - GET ADDRESS OF USER STATUS

D.ALTI:	MOV	#D.USTA,R4	; ADDRESS OF STATUS
	BR	D.MAS2		; RETURN

; PROCESS " - GET TEXT

D.TEXT:	JSR	PC,D.GET	; GET NEXT CHARACTER
	CLR	R2		; RAD50/ASCII INDICATOR
	CMP	R0,#33		; ALTMODE?
	BNE	D.TEX1		; BRANCH IF NOT
	INC	R2		; SET INDICATOR
	JSR	PC,D.GET	; GET NEXT CHARACTER
D.TEX1:	MOV	R1,R5		; DELIMETER (EXACT CHARACTER)
D.TEX2:	JSR	PC,D.GET	; GET CHARACTER
	CMP	R1,R5		; DELEMETER?
	BEQ	D.TEX3		; BRANCH IF SO
	MOV	R1,R0		; PUT IN ARGUMENT PLACE
	JSR	PC,D.PTSM	; PUT IN SYMBOL
	BR	D.TEX2		; LOOP
D.TEX3:	TST	R2		; ASCII?
	BNE	D.TEX4		; BRANCH IF NOT
	MOV	D.SYM,R4	; GET ASCII CHARACTERS
	BR	D.MAS2		; RETURN
D.TEX4:	MOV	#D.SYM,R0	; ADDRESS OF FIRST THREE CHARACTERS
	JSR	PC,D.RD50	; CONVERT TO RAD50
	MOV	R0,R4		; NOW CURRENT VALUE
	BR	D.MAS2		; RETURN

; PROCESS <CALL> - SOFT RESTART

	.IF	DF,D.GDP
D.SOFT:	 MOV	#1004,R5	; ADDRESS OF SOFT RESTART
	 BR	D.GO3		; GO THERE
	.ENDC
; PROCESS G - GO

D.GO:	MOV	D.SVR4,R5	; GET STARTING ADDRESS
	TST	D.SVR2		; STARTING ADDRESS SPECIFIED?
	BNE	D.GO3		; IF NOT, USE USER SA
	MOV	JOBSA,R5	; GET STARTING ADDRESS
D.GO3:	TST	(R5)		; VALID ADDRESS? NXM IF NOT
	JSR	PC,D.CRLF
D.GO5:	TST	D.SD.T		; SHOULD THE T-BIT BE ON?
	BEQ	D.GO2		; BRANCH IF NO
D.GO4:	BIS	#20,D.USTA	; SET T-BIT
D.GO2:	MOV	R5,D.UR7
	JSR	PC,D.REST	; RESTORE REGISTERS
	MOV	D.USTA,-(SP)	;    AND STATUS
	MOV	D.UR7,-(SP)	;    AND PC
D.GO1:	RTI			; THIS IS "RTT" IF 11/40...

; PROCESS P - PROCEED 

D.PROC:	TST	R2		; CHECK FOR ILLEGAL COUNT
	BNE	D.ERRA		; JUMP IF ILLEGAL
	MOV	D.UR7,R5	; GET PC
	TST	(R5)		; VALID ADDRESS? NXM IF NOT
	MOVB	D.P,R0		; DID WE ENTER VIA A BREAK?
	BLT	D.PRO3		; NO, RETURN TO CALLER
	MOV	D.SVR4,R4	; GET COUNT
	TST	D.SVR2		; WAS COUNT SPECIFIED?
	BNE	D.PRO1		; NO
	MOV	#1,R4		; SET COUNT OF 1
D.PRO1:	CMPB	D.ALTF,#1	; AUTOMATIC PROCEDE?
	BLE	D.PRO6		; BRANCH IF NOT
	NEG	R4		; SET TO AUTOMATIC
D.PRO6:	MOV	R4,D.CT(R0)	; PUT AWAY COUNT
D.PRO7:	JSR	PC,D.CRLF	; CARRIAGE RETURN LINE FEED
D.PRO2:	INCB	D.T		; SET SPECIAL BIT TO 1
	MOV	R5,D.TPC	; SAVE PC FOR 11/40 KLUDGE
	BR	D.GO5
D.PRO3:	TST	D.SVR2		; COUNT SPECIFIED?
	BEQ	D.GO3		; NO, OK, RETURN TO CALLER OF DDT
D.ERRA:	JMP	D.ERR		; ELSE ERROR
D.PRO4:	TSTB	D.MACH		; 11/40,45?
	BEQ	D.PRO5		; NO, DON'T NEED TO KLUDGE
	CMP	R5,D.TPC	; DID WE NOT EXECUTE THE BROKEN INSTRUCTION?
	BEQ	D.GO4		; YES, TRY IT AGAIN
D.PRO5:	CLRB	D.T		; WE CAN CONTINUE NORMALLY
	TSTB	D.S		; UNLESS WE ARE SINGLE STEPPING
	BEQ	D.GO5
	BR	D.BRK2		; IN WHICH CASE WE BREAK IMMEDIATELY
; PROCESS X - EXECUTE INSTRUCTION

D.EXEC:	TST	D.SVR2		; ANY INSTRUCTION?
	BEQ	D.ERRA		; ERROR IF NOT
	MOV	#D.SVR4,R5	; INSTRUCTION STARTING ADDRESS
	TST	D.PARO		; RELOCATE FIRST WORD?
	BEQ	D.EXE1		; BRANCH IF NOT
	SUB	#D.PARS+2,D.PARS; RELOCATE FIRST WORD
D.EXE1:	TST	D.PARO+2	; RELOCATE SECOOND WORD?
	BEQ	D.EXE3		; BRANCH IF NOT
	SUB	#D.PARS+4,D.PARS+2 ; RELOCATE SECOND WORD
D.EXE3:	MOV	D.UR7,D.SVR7	; SAVE PC
	BR	D.GO5		; EXECUTE INSTRUCTION

D.EXE2:
.IIF NDF,D.LSI,MOV @#PS,D.USTA	; GET PS
.IIF DF,D.LSI,MFPS D.USTA	; GET PS
	MOV	D.SVR7,D.UR7	; RESTORE CORRECT PC
	JSR	PC,D.SAVE	; SAVE ALL REGISTERS
	BR	D.BRK8		; RETURN

; ERROR TRAPS

D.NXMT:	MOV	#D.NM,D.ERF	; NXM TRAP SERVICE
	BR	D.BRK		; HANDLE BREAKPOINT
D.ILGT:	MOV	#D.IM,D.ERF	; ILLEGAL INSTRUCTION
; BREAKPOINT HANDLER

D.BRK:	MOV	(SP)+,D.UR7	; SAVE PC AND STATUS
	BIC	#20,(SP)	; TURN OFF T-BIT
	MOV	(SP)+,D.USTA	; SAVE PS
	JSR	PC,D.SAVE	; SAVE VARIOUS REGISTERS
	MOV	D.UR7,R5	; GET PC, IT POINTS TO THE INSTRUCTION
	TST	D.ERF		; TEST ADDRESS OF ERROR MESSAGE
	BNE	D.BRK7		; BRANCH IF ERROR
	TSTB	D.T		; WERE WE PROCEEDING AFTER A BREAK?
	BGT	D.PRO4		; YES, FIX IT UP
D.BRK2:	MOV	#D.BKP*2,R4	; GET A COUNTER
	TSTB	D.S		; DID WE ENTER VIA BPT?
	BNE	D.BRK3
	TST	-(R5)		; YES, BACK UP A WORD
D.BRK3:	CMP	R5,D.BKTB-2(R4)	; IS THIS THE BPT?
	BEQ	D.BRK4		; BRANCH IF YES
	SUB	#2,R4
	BHI	D.BRK3		; LOOP, UNLESS DONE
	TSTB	D.S		; SINGLE STEP MODE?
	BEQ	D.BRK6		; NO, WE SHOULDN'T HAVE BEEN CALLED.
D.BRK4:	MOV	R5,D.UR7	; UPDATE THE PC, IF WE DECREMENTED IT
	MOVB	R4,D.P		; AND SET THE BREAKPOINT FLAG
	TST	D.CT(R4)	; AUTOMATIC PROCEDE?
	BMI	D.BRK9		; BRANCH IF GETTING THERE
	BEQ	D.BRKA		; BRANCH IF AUTOMATIC PROCEDE
	DEC	D.CT(R4)	; TEST REPEAT COUNT
	BLE	D.BRKC		; BRANCH IF NO REPEAT
D.BRKD:	BR	D.PRO2		; PROCEDE
D.BRKC:	MOV	#1,D.CT(R4)	; RESET COUNT TO 1
D.BRKA:	MOV	D.CT(R4),-(SP)	; SAVE COUNT
	ASR	R4		; FIX IT
	ADD	#'0,R4		; MAKE IT ASCII
	MOVB	R4,D.BMES+1	; PUT IN STRING
	MOV	#D.BMES,R4	; REST OF MESSAGE
	MOV	#D.BMES+6,R3	; END OF MESSAGE
	JSR	PC,D.STYP	; TYPE IT
	MOV	R5,R0		; GET ADDRESS OF BREAK
	MOV	R5,-(SP)	; AND SAVE IN CASE OF AUTO REPEAT
	JSR	PC,D.RFND	; RELOCATE
	MOVB	D.P,R4		; PROCEED ALLOWED?
	BMI	D.BRK8		; NO
	MOV	D.OPEN(R4),R0	; ANY WORD TO OPEN AT BREAKPOINT?
	BEQ	D.BRKB		; BRANCH IF NOT
	MOV	R0,D.DOT	; PUT IN CURRENT WORD
	JSR	PC,D.TTAB	; TYPE A TAB
	JSR	PC,D.OP3	; OPEN IT
D.BRKB:	MOV	(SP)+,R5	; RESTORE R5
	TST	(SP)+		; AUTOMATIC PROCEDE?
	BNE	D.BRK8		; RETURN IF NOT
	TSTB	@#D.RCSR	; CHARACTER TYPED?
	BMI	D.BRK8		; EXIT IF SO
	JMP	D.PRO7		; CONTINUE BREAKPOINT
D.BRK9:	INC	D.CT(R4)	; COUNT 'EM OFF
	BMI	D.BRKD		; PROCEDE IF STILL NEGATIVE
	BR	D.BRKA		; DO THE BREAK
D.BRK6:	MOV	#D.BE,D.ERF	; ERROR: UNEXPECTED BREAK
D.BRK7:	MOV	D.UR7,R0	; GET ADDRESS OF BREAK
	JSR	PC,D.RFND	; RELOCATE
	MOV	D.ERF,R3	; GET CODE
	MOV	R3,R4		; OBTAIN END
	ADD	#4,R3		; BY ADDING 4 TO BEGIN
	JSR	PC,D.STYP	; TYPE MESSAGE
	CLR	D.ERF		; REMOVE TRACES OF THIS ENTRY
	MOVB	#-1,D.P		; DISALLOW PROCEED
	CLRB	D.T		; TURN OFF BIT
D.BRK8:	JMP	D.DCD		; RETURN
; CONVERT 3 ASCII CHARACTERS AT (R0) TO RAD50 WORD IN R0

D.RD50:	MOV	R2,-(SP)	; SAVE R2
	MOV	R1,-(SP)	; SAVE R1 ALSO
	MOV	#-3,-(SP)	; CHARACTER LOOPER
	CLR	R2		; NOW CLEAR IT
D.RD51:	CLR	R1		; OFFSET OF CHARACTERS
D.RD52:	CMPB	D.RDTB(R1),(R0)	; CHARACTER MATCH?
	BEQ	D.RD53		; BRANCH IF SO
	INC	R1		; NEXT CHARACTER
	CMP	R1,#D.ENTB	; AT END OF TABLE
	BLT	D.RD52		; BRANCH IF NOT
D.ERRF:	JMP	D.ERR		; BAD CHARACTERS
D.RD53:	ASL	R2		; MULTIPLY BY 2
	ASL	R2		; MULTIPLY BY 4
	ASL	R2		; MULTIPLY BY 8
	MOV	R2,-(SP)	; STORE AWAY
	ASL	R2		; MULTIPLY BY 16
	ASL	R2		; MULTIPLY BY 32
	ADD	(SP)+,R2	; ADD 8X TO MAKE IT 40X
	ADD	R1,R2		; PUT IN NEW CHARACTER
	INC	R0		; POINT TO NEXT CHARACTER
	INC	(SP)		; INCREMENT LOOPER
	BMI	D.RD51		; BRANCH IF MORE
	TST	(SP)+		; RESET STACK
	MOV	R2,R0		; RESULT IN R0
	MOV	(SP)+,R1	; RESTORE R1
	MOV	(SP)+,R2	; RESTORE R2
	RTS	PC		; RETURN

; CONVERT RAD50 WORD IN R0 TO THREE ASCII CHARACTERS AT (R1)

D.CHAR:	MOV	R1,R3		; INDEX HERE SINCE D.DIVD WILL USE R1
	MOV	#1600.,R2	; OTHER OPERAND
	JSR	PC,D.DIVD	; DIVIDE THEM
	MOVB	D.RDTB(R0),(R3)+; MOVE A CHARACTER IN
	MOV	#40.,R2		; OPERAND
	MOV	R1,R0		; GET NEW NUMERATOR
	JSR	PC,D.DIVD	; DIVIDE THEM
	MOVB	D.RDTB(R0),(R3)+; MOVE ANOTHER CHARACTER IN
	MOVB	D.RDTB(R1),(R3)+; MOVE LAST CHARACTER IN
	MOV	R3,R1		; RESTORE FOR THE USER
	RTS	PC		; RETURN
; SAVE THE WORLD

D.SAVE:	MOV	(SP)+,D.XXX	; PICK UP RETURN ADDRESS FROM STACK
	MOV	SP,D.UR6	; SAVE USER STACK ADDRESS
	MOV	#D.UR6,SP	; SET TO INTERNAL STACK
	MOV	R5,-(SP)	; SAVE
	MOV	R4,-(SP)	; REGISTERS
	MOV	R3,-(SP)	; 0
	MOV	R2,-(SP)	;  THRU
	MOV	R1,-(SP)	;      5
	MOV	R0,-(SP)	; HERE
	.IF	DF,D.GDP
	 TRAP	72		; USECLR
D.SAV9:	 NOP			; MAY HAVE USERET
	 TRAP	107		; SCRUNB
	.ENDC
	TST	D.SD.T		; TEST D.S AND D.T
	BNE	D.SAV3		; SKIP BREAKPOINTS IF SO
	CLR	R4		; REMOVE ALL BREAKPOINTS
D.SAV1:	MOV	D.BKTB(R4),R5	; GET ADDRESS OF BREAKPOINT
	BEQ	D.SAV2		; BRANCH IF NOT FILLED
	MOV	D.UIN(R4),(R5)	; RESTORE USER'S INSTRUCTION
D.SAV2:	TST	(R4)+		; LOOP
	CMP	R4,#D.BKP*2	; AT END?
	BLT	D.SAV1		; RE-LOOP UNTIL DONE
D.SAV3:	MOV	#340,R1		; PS
	MOV	#4,R0		; START FILLING AT WORD 4
	MOV	(R0),-(SP)	; 4
	MOV	#D.SAV5,(R0)+	; INTERNAL NXMS
	MOV	(R0),-(SP)	; 6
	MOV	R1,(R0)+	; SET VECTOR PS

	MOV	(R0),-(SP)	; 10
	MOV	#D.SAV5,(R0)+	; INTERRUPT FOR ILLEGAL INSTRUCTION
	MOV	(R0),-(SP)	; 12
	MOV	R1,(R0)+	; SET VECTOR PS

	MOV	#D.BRK,(R0)+	; BPT VECTOR
	MOV	R1,(R0)		; SET VECTOR PS
	MOV	@#D.RCSR,-(SP)	; SAVE KEYBOARD STATUS
	CLR	@#D.RCSR	; TURN OFF ALL INTERRUPTS
	.IF	DF,D.KSR
	 MOV	@#D.TCSR,-(SP)	; SAVE PRINTER STATUS
	 CLR	@#D.TCSR	; REMOVE ALL ENABLES
	.ENDC
	MOVB	#2,D.MACH	; SET MACHINE TO 11/45
	SXT	R1		; 11/40,45 INSTRUCTION
	CMPB	D.MACH,#1	; 11/15?
	BEQ	D.SAV4		; BRANCH IF NOT
	MOV	#RTT,D.GO1	; USE RTT INSTRUCTION
D.SAV4:	TST	@#177772	; WORD ONLY EXISTS ON 11/45
	MOV	#D.ERR,@#4	; RESET NXM ADDRESS
	MOV	#D.ILGT,@#10	; ILLEGAL INSTRUCTION
	JMP	@D.XXX		; RETURN

D.SAV5:	DECB	D.MACH		; IT FAILED, DIFFERENT MACHINE
	RTI			; RETURN
; RESTORE THE WORLD AS WE FOUND IT

D.REST:	MOV	(SP)+,D.XXX	; GET RETURN ADDRESS FROM STACK
	TST	D.SD.T		; TEST D.S AND D.T
	BNE	D.RES3		; SKIP BREAKPOINTS IF SO
	MOV	#<D.BKP*2>-2,R4	; RESTORE ALL BREAKPOINTS
D.RES1:	MOV	D.BKTB(R4),R5	; GET ADDRESS OF BREAKPOINT
	BEQ	D.RES2		; BRANCH IF NO BREAKPOINT
	MOV	(R5),D.UIN(R4)	; SAVE CONTENTS OF USER LOCATION
	MOV	#BPT,(R5)	; PUT BREAKPOINT THERE
D.RES2:	SUB	#2,R4		; DECREMENT
	BGE	D.RES1		; RE-LOOP UNTIL DONE
D.RES3:	MOV	#D.STK,SP	; SET STACK POINTER TO BASE
.IIF DF,D.KSR,MOV (SP)+,@#D.TCSR; PUT TELETYPE STATUS BACK
	MOV	(SP)+,@#D.RCSR	; PUT KEYBOARD STATUS BACK
	MOV	#12,R0		; RESTORE HIS VECTORS
	MOV	(SP)+,(R0)	; 12
	MOV	(SP)+,-(R0)	; 10
	MOV	(SP)+,-(R0)	; 6
	MOV	(SP)+,-(R0)	; 4
.IIF DF,D.GDP,TRAP 144		; USERET
	MOV	(SP)+,R0	; RESTORE
	MOV	(SP)+,R1	; USER
	MOV	(SP)+,R2	; REGISTERS
	MOV	(SP)+,R3	;  0
	MOV	(SP)+,R4	;  THRU
	MOV	(SP)+,R5	;    5
	MOV	(SP),SP		; RESTORE USER STACK
	JMP	@D.XXX		; AND RETURN
; TYPE R0 IN ADDRESS FORM

D.RFND:	MOV	R1,-(SP)	; SAVE R1
	MOV	R0,-(SP)	; SAVE ADDRESS FOR LATER
	CMP	R0,D.SVR4	; IS IT THE ADDRESS WE ARE LOOKING FOR?
	BNE	D.RFN2		; BRANCH IF NOT
	INCB	D.FIND		; MARK IT FOUND
D.RFN2:	TST	D.IFMT		; ABSOLUTE ADDRESSING?
	BNE	D.RFN7		; BRANCH IF SO
	JSR	PC,D.GTSM	; GET SYMBOL (IF ANY)
	TST	R1		; ANY SYMBOL?
	BEQ	D.RFN7		; BRANCH IF NOT
	MOV	R0,-(SP)	; SAVE OFFSET VALUE
	MOV	#6,-(SP)	; REPEAT COUNT
D.RFN5:	MOVB	(R1)+,R0	; GET CHARACTER
	CMPB	R0,#40		; IS IT A BLANK?
	BEQ	D.RFN6		; DONE IF SO
	JSR	PC,D.TYPE	; TYPE IT
	DEC	(SP)		; DECREMENT COUNT
	BGT	D.RFN5		; LOOP IF MORE
D.RFN6:	TST	(SP)+		; RESET STACK
	MOV	(SP)+,R1	; GET OFFSET
	BEQ	D.RFN1		; BRANCH IF NONE
	MOV	#'+,R0		; MAKE A PLUS
	JSR	PC,D.TYPE	; TYPE IT
	MOV	R1,R0		; GET OFFSET
D.RFN7:	JSR	PC,D.TYPN	; TYPE THE NUMBER
D.RFN1:	MOV	(SP),D.LASW	; LAST TYPED WORD
	MOV	(SP)+,D.LASV	; LAST TYPED ADDRESS
	MOV	(SP)+,R1	; RESTORE R1
	RTS	PC		; RETURN

; CLOSE WORD OR BYTE

D.CLSE:	TST	R2		; IF NO NUMBER WAS TYPED THERE IS
	BEQ	D.CLS1		; NOTHING TO CLOSE
	CMP	D.CAD,#177776	; ANY OPEN WORD?
	BEQ	D.CLS1		; BRANCH IF NOT
	CLR	D.LFIN		; NO LINE FEED INCREMENT
	CMP	#1,D.BW		; BYTE MODE?
	BEQ	D.CLS2		; JUMP IF BYTE MODE
	MOV	D.CAD,R2	; WORD ADDRESS
	MOV	R4,(R2)+	; STORE VALUE
	MOV	R2,R4		; PUT INTO R4 FOR COMPUTATION
	SUB	D.CADC,R4	; SUBTRACT COPY
	BGT	D.CLS1		; BRANCH IF NO MORE
	MOV	#2,D.LFIN	; LINE FEED INCREMENT
	MOV	D.PARS,(R2)	; MOVE ANOTHER WORD (2 OR 3 WORD INST)
	SUB	D.PARO,(R2)+	; RELOCATE WORD
	TST	R4		; THIRD PARAMETER?
	BEQ	D.CLS1		; BRANCH IF NOT
	MOV	#4,D.LFIN	; LINE FEED INCREMENT
	MOV	D.PARS+2,(R2)	; PUT THIRD WORD IN
	SUB	D.PARO+2,(R2)	; RELOCATE WORD
	BR	D.CLS1		; FINISH UP
D.CLS2:	MOVB	R4,@D.CAD	; STORE BYTE
D.CLS1:	MOV	#177776,D.CAD	; CLOSE WORD
	RTS	PC		; RETURN
; SUBROUTINE TO TYPE @D.CAD IN NUMBER FORM

D.CADV:	CMP	#1,D.BW		; BYTE MODE?
	BEQ	D.CAD1		; BRANCH IF SO
	MOV	@D.CAD,R0	; GET OPERAND
	JSR	PC,D.RFND	; TYPE NUMBER
	BR	D.ASC2		; RETURN
D.CAD1:	MOVB	@D.CAD,R0	; GET OPERAND
	BIC	#177400,R0	; CLEAR HIGH BITS
	JSR	PC,D.TYPN	; TYPE IT
	BR	D.ASC2		; RETURN

; SUBROUTINE TO TYPE @D.CAD IN ASCII FORM

D.ASCI:	MOV	D.CAD,R5	; GET ADDRESS
	MOVB	(R5)+,R0	; GET FIRST CHARACTER
	BIC	#177400,R0	; CLEAR HIGH BITS
	MOV	R0,D.LASV	; LAST TYPED DATA
	MOV	R0,D.LASW	; LAST TYPED WORD TOO
	JSR	PC,D.TYPE	; TYPE IT
	MOVB	(R5),R0		; GET NEXT CHARACTER
	ROR	R5		; EXAMINE LOW BIT
	BCC	D.ASC2		; BRANCH IF CLEAR
	JSR	PC,D.TYPE	; TYPE IT
D.ASC3:	MOV	@D.CAD,D.LASV	; LAST TYPED DATA
	MOV	@D.CAD,D.LASW	; LAST TYPED WORD TOO
D.ASC2:	CLR	D.LFIN		; TURN OFF LINE-FEED SKIPPING
D.RTS:	RTS	PC		; RETURN

; SUBROUTINE TO TYPE @D.CAD IN MULTI-BYTE FORM

D.PART:	MOV	@D.CAD,R5	; GET WORD
	MOV	#16.,-(SP)	; BIT COUNT
D.PAR5:	MOV	R5,R0		; ACCUMULATOR FOR BYTE
	MOV	#177777,R3	; MASK FOR BYTE
	MOV	D.SIZE,R2	; BYTE SIZE
D.PAR1:	ASR	R5		; REMOVE ONE BIT
	ASL	R3		; ONE MORE BIT IN MASK
	DEC	(SP)		; ONE LESS BIT IN WORD
	BLE	D.PAR2		; EXIT IF DONE
	DEC	R2		; ONE LESS BIT IN BYTE
	BGT	D.PAR1		; LOOP IF NOT DONE
D.PAR2:	BIC	R3,R0		; MASK WORD
	JSR	PC,D.TYPN	; TYPE BYTE
	TST	(SP)		; ALL DONE?
	BLE	D.PAR4		; BRANCH IF SO
	MOV	#',,R0		; COMMA
	JSR	PC,D.TYPE	; TYPE IT
	BR	D.PAR5		; GET NEXT BYTE
D.PAR4:	TST	(SP)+		; FIX STACK
	BR	D.ASC3		; RETURN

; SUBROUTINE TO TYPE @D.CAD IN RAD50 FORM

D.RADC:	MOV	@D.CAD,R0	; PUT VALUE IN R0
	MOV	#D.SYM,R1	; ADDRESS FOR RESULT
	JSR	PC,D.CHAR	; MAKE CHARACTERS OF IT
	MOV	#D.SYM,R4	; ADDRESS OF FIRST CHARACTER
	MOV	#D.SYM+2,R3	; ADDRESS OF LAST CHARACTER
	JSR	PC,D.STYP	; TYPE THEM
	BR	D.ASC3		; DONE

; SUBROUTINE TO TYPE @D.CAD IN INSTRUCTION FORMAT

D.INST:	MOV	D.CAD,R5	; PUT CURRENT ADDRESS INTO DECODE
	JSR	PC,D.TTAB	; TYPE TAB
	JSR	PC,D.DC49	; DECODE IT
	SUB	D.CAD,R5	; GET INSTRUCTION LENGTH
	TST	-(R5)		; DECREMENT TO BE OFFSET OF INSTR
	CMP	D.DOT,D.CAD	; ARE WE AT THE DOT?
	BNE	D.INS2		; DON'T SET INCREMENT IF NOT
	MOV	R5,D.LFIN	; PUT IN LINE-FEED INCREMENT
D.INS2:
;	ASR	R5		; DIVIDE BY TWO
;	BEQ	D.INS4		; BRANCH IF NOT ZERO
;	ADD	#'1,R5		; ASCIIZE
;	MOVB	R5,D.WAMS+1	; FILL IN NUMBER OF WORDS
;	MOV	#D.WAMS,R4	; BEGIN WARNING MESSAGE
;	MOV	#D.WAMS+7,R3	; END WARNING MESSAGE
;	JSR	PC,D.TTAB	; TYPE A TAB
;	JSR	PC,D.STYP	; TYPE IT
D.INS4:	MOV	@D.CAD,D.LASW	; LAST TYPED WORD
	RTS	PC		; RETURN
; GET A CHARACTER INTO R0

D.GET:	.IF	NDF,D.KSR
	 TSTB	@#D.RCSR	; CHARACTER TYPED?
	 BPL	D.GET		; LOOP UNTIL FOUND
	 MOVB	@#D.RDB,R0	; GET A CHARACTER
	.ENDC
	.IF	DF,D.KSR
	 JSR	PC,D.POLL	; CHECK FOR CHARACTERS IN I/O BUFFER
	 CMP	D.INPU,D.OUTP	; ANY CHARACTERS TYPED?
	 BEQ	D.GET		; LOOP IF BUFFER EMPTY
	 MOVB	@D.OUTP,R0	; GET CHARACTER FROM BUFFER
	 INC	D.OUTP		; POINT TO NEXT CHARACTER
	 CMP	D.OUTP,#D.ENDB	; AT END OF BUFFER?
	 BNE	D.GET9		; BRANCH IF NOT
	 MOV	#D.BUFR,D.OUTP	; WRAP-AROUND
D.GET9:	.ENDC
.IIF DF,D.GDP,TRAP	64	; KEYASC
	BIC	#177600,R0	; CLEAR META, CNTL AND SHIFT STUFF
	MOV	R0,R1		; EXACT (UNFOLDED COPY IN R1)
	BEQ	D.GET		; IGNORE NULLS
	CMPB	R0,#15		; SEE IF A <CR>
	BNE	D.GET2		; BRANCH IF NOT
	MOV	#12,R0		; LINE FEED
	JSR	PC,D.TYPE	; TYPE IT
	MOV	#15,R0		; RESET TO CR
D.GET2:	CMPB	R0,#177		; IS IT A BACKSPACE
	BEQ	D.GET5		; GUARANTEED TO GET A ?
	CMP	R0,#12		; IS IT A LINE FEED?
	BEQ	D.GET1		; IF SO, SAVE THE PAPER
	CMPB	R0,#33		; IS IT AN ESCAPE?
	BEQ	D.GET4		; TYPE DOLLAR SIGN IF SO
	.IF	DF,D.KSR
	 CMPB	R0,#175		; IS IT AN ALTMODE?
	 BGE	D.GET4		; TYPE DOLLAR SIGN IF SO
	.ENDC
	JSR	PC,D.TYPE	; ECHO CHARACTER
	CMPB	#'a,R0		; FOLD TO UPPER CASE
	BGT	D.GET1		; BRANCH IF NOT A LETTER
	CMPB	#'z,R0		; IS IT IN ALPHABET?
	BLT	D.GET1		; BRANCH IF STILL NOT
	SUB	#'a-'A,R0	; FOLD DOWN
D.GET1:	RTS	PC		; RETURN
D.GET4:	MOV	#'$,R0		; DOLLAR SIGN
	JSR	PC,D.TYPE	; TYPE IT
	MOV	#33,R0		; RESTORE R0
	RTS	PC		; RETURN
D.GET5:	MOV	#'X,R0		; TYPE "XXX"
	JSR	PC,D.TYPE	; TYPE FIRST
	JSR	PC,D.TYPE	; TYPE SECOND
	JMP	D.ERRO		; JUMP TO LAST
	.IF	DF,D.KSR
D.POLL:	 TSTB	@#D.RCSR	; ANY CHARACTER TYPED?
	 BPL	D.POL1		; BRANCH IF NOT
	 MOVB	@#D.RDB,@D.INPU	; PUT CHARACTER IN BUFFER
	 INC	D.INPU		; NEXT
	 CMP	D.INPU,#D.ENDB	; AT END OF BUFFER?
	 BNE	D.POL1		; BRANCH IF NOT
	 MOV	#D.BUFR,D.INPU	; WRAP-AROUND
D.POL1:	 RTS	PC		; RETURN
	.ENDC

; TYPE A TAB

D.TTAB:
.IIF	NDF,D.KSR,MOV	#11,R0	; TAB
.IF	DF,D.KSR
	TSTB	D.NOTY		; IN NON-TYPEOUT MODE?
	BNE	D.TYP8		; EXIT IF SO
	MOV	#40,R0		; SPACE
	JSR	PC,D.TYPE	; TYPE IT
	JSR	PC,D.TYPE	;  AND TYPE IT AGAIN
;	JMP	D.TYPE		;   AND A THIRD SPACE (LIKE DDT-10)
	.ENDC

; TYPE THE CHARACTER IN R0

D.TYPE:	TSTB	D.NOTY		; SHOULD WE TYPE?
	BNE	D.TYP8		; BRANCH IF NOT
.IIF	DF,D.GDP,TRAP	120	; SCRRTN
.IIF	DF,D.GT40,EMT	0
	.IF	DF,D.KSR
	 JSR	PC,D.TYP3	; TYPE CHARACTER
	 CMPB	R0,#15		; CARRIAGE RETURN?
	 BEQ	D.TYP2		; ZERO POSITION COUNTER IF SO
	 BITB	#140,R0		; CONTROL CHARACTER?
	 BEQ	D.TYP1		; RETURN IF SO
	 DECB	D.CPOS		; INCREMENT CHARACTER POSITION
	 BPL	D.TYP1		; RETURN IF NOT
	 MOV	R0,-(SP)	; SAVE CHARACTER
	 MOV	#15,R0		; YES, GENERATE CARRIAGE RETURN
	 JSR	PC,D.TYP3	; TYPE IT
	 MOV	#12,R0		; AND A LINE FEED
	 JSR	PC,D.TYP3	; TYPE IT
	 MOV	(SP)+,R0	; RESTORE CHARACTER
D.TYP2:	 MOVB	#71.,D.CPOS	; CLEAR CHARACTER POSITION
D.TYP1:	 RTS	PC		; RETURN
D.TYP3:	 TSTB	@#D.TCSR	; PRINTER READY FOR CHARACTER?
	 BPL	D.TYP3		; LOOP IF NOT
	 MOVB	R0,@#D.TDB	; PUT OUT CHARACTER
	 JSR	PC,D.POLL	; CHECK FOR TYPED-IN CHARACTERS
	.ENDC
D.TYP8:	RTS	PC		; RETURN

; TYPE CARRIAGE RETURN LINE FEED

D.CRLF:	MOV	#D.CR+1,R3	; LWA <CR,LF>
	MOV	#D.CR,R4	; FWA

; TYPE A STRING STARTING AT R4 AND ENDING AT R3

D.STYP:	CMP	R3,R4		; CHECK FOR COMPLETION
	BLO	D.GET1		; EXIT WHEN DONE
	MOVB	(R4)+,R0	; GET A CHARACTER
	JSR	PC,D.TYPE	; TYPE ONE CHARACTER
	BR	D.STYP		; LOOP UNTIL DONE
; SUBROUTINE TO TYPE R0 IN CURRENT RADIX

D.TYPN:	MOV	R0,D.LASV	; MARK LAST NUMBER TYPED
	MOV	R0,D.LASW	; LAST TYPED WORD TOO
	MOV	D.DVTB,R2	; GET RADIX
	CMP	R2,#10.		; DECIMAL?
	BEQ	D.TYP4		; YES
D.TYP5:	JSR	PC,D.DIVD	; DIVIDE IT.
	ADD	#60,R1		; CONVERT REMAINDER TO ASCII
	MOV	R1,-(SP)	; AND SAVE IT.
	TST	R0		; DONE?
	BEQ	D.TYP7		; YES, TYPE THE DIGIT AND RETURN
D.TYP6:	JSR	PC,D.TYP5	; CALL OURSELF RECURSIVELY
D.TYP7:	MOV	(SP)+,R0	; RESTORE THE DIGIT
	BR	D.TYPE		; PRINT IT, AND RETURN

D.TYP4:	MOV	#'.,-(SP)	; PUT A . AT THE END OF THE NUMBER
	MOV	R0,R3		; GET THE NUMBER
	BPL	D.TYP6		; AND TYPE IF POSITIVE
	MOV	#'-,R0		; ELSE PRINT A -
	JSR	PC,D.TYPE
	MOV	R3,R0		; RESTORE NUMBER
	NEG	R0		; BUT TAKE ABSOLUTE VALUE
	BR	D.TYP6

; DIVISION ROUTINE - R1 (HIGH) AND R0 (LOW)/R2=R0 REMAINDER R1

D.DIVD:	MOV	#16.,-(SP)	; SHIFT COUNT
	CLR	R1		; ASSUME NO HIGH PART
D.DIV1:	ASL	R0		; DOUBLE PRECISON SHIFT
	ROL	R1
	CMP	R2,R1		; WILL DIVISOR GO IN?
	BHI	D.DIV2
	SUB	R2,R1
	INC	R0
D.DIV2:	DEC	(SP)
	BGT	D.DIV1		; SOB?
	TST	(SP)+
	RTS	PC
; TYPE WORD(S) AT R5 IN INSTRUCTION FORMAT

D.DC49:	MOV	(R5)+,R0	; GET INSTRUCTION INTO R0
	MOV	#D.TOPS+2,R1	; POINT TO ARRAY OF INSTRUCTION VALUES
	MOV	R0,R4		; SAVE INSTRUCTION
	CLR	R3		; DON'T TYPE A "B"
	BIC	#100000,R0	; START OUT LOOKING FOR INS. WITHOUT "B"
D.LOOP:	CMP	R0,(R1)+	; DOES INSTRUCTION FALL IN HERE?
	BHI	D.LOOP		; NO, LOOP
	CMP	R4,R0		; DID WE GET REAL INSTRUCTION MATCH?
	BEQ	D.FOUN		; YES
	MOV	R4,R0		; NO, BUT DO SO NEXT TIME
	TSTB	D.LEGS-D.TOPS-4(R1)	; BYTE INSTRUCTION?
	BPL	D.LOOP		; NO!
	DEC	R3		; PRINT A  "B"
D.FOUN:	MOVB	D.LEGS-D.TOPS-4(R1),R2	; GET LEGAL CONSIDERATION BYTE
	BIC	#177774,R2	; CLEAR HIGH BITS
	CMPB	R2,D.MACH	; MACHINE TYPE RIGHT?
	BGT	D.N16		; TYPE NUMBER IF BAD
	ADD	#D.COUS-D.TOPS-4,R1	; ADD IN ADDRESS OF STRING
	MOV	(R1)+,R2	; GET OFFSET OF CHARACTERS
	BIC	#177400,R2	; TURN OFF EXTRA CRUFT
D.DC6:	CMPB	R2,(R1)		; AT END?
	BEQ	D.DC3		; BRANCH IF SO
	MOVB	D.STRS(R2),R0	; GET A CHARACTER
	JSR	PC,D.TYPE	; TYPE IT
	INC	R2		; NEXT CHARACTER
	BR	D.DC6		; LOOP
D.DC3:	TST	R3		; BYTE INSTRUCTION?
	BEQ	D.DONE		; BRANCH IF NOT
	MOV	#'B,R0		; BYTE INSTRUCTION: TYPE "B"
	JSR	PC,D.TYPE	; TYPE IT
D.DONE:	MOVB	-(R1),R3	; RE-GET LEGALITY BYTE
	BIC	#177703,R3	; GET LEGAL CONSIDERATION
	CMP	R3,#10		; TYPE A SPACE AFTER OP-CODE?
	BLE	D.NOBL		; BRANCH IF NOT
	MOV	#' ,R0		; SPACE
	JSR	PC,D.TYPE	; TYPE IT
D.NOBL:	MOV	R4,R0		; GET INSTRUCTION BACK
	ASL	R4		; GET OPERAND THAT STARTS AT BIT 6
	ASL	R4		; WITH TWO SHIFTS AND...
	SWAB	R4		; A SWAB
	ASR	R3
	JMP	@D.PARM(R3)	; TYPE PARAMETERS

D.DC7:	MOV	R0,R1		; GET R1 FOR D.DC5
	ADD	#D.MOD7,R1	; DISPLACEMENT OF OPENING CHARACTERS
	MOVB	(R1),R2		; GET OFFSET OF CHARACTERS
	CMPB	D.FIRS(R2),#'?	; IS IT LEGAL?
	BEQ	D.DC50		; BRANCH IF NOT
	JSR	PC,D.DC5	; TYPE THEM
	CMP	R0,#6		; RELATIVE ADDRESSING?
	MOV	(R5)+,R0	; NOTE THAT THIS LEAVES CARRY ALONE
	BCS	D.N16		; BRANCH IF IMMEDIATE
D.N17:	ADD	R5,R0		; FUDGE FOR RELATIVE.
D.N16:	JMP	D.RFND		; TYPE IN CURRENT ADDRESSING MODE

D.SSDD:	MOV	R0,-(SP)	; SAVE SECOND PARAMETER
	MOV	R4,R0		; GET FIRST ONE
	JSR	PC,D.DD		; TYPE IT
	BR	D.SS		; DO THE REST
D.CZVN:	MOV	#D.NZVC,R1	; LOOP ON BITS OF CODE
	MOV	R0,R2		; SAVE OPERATION IN R2
	JSR	PC,(PC)		; DO WHAT FOLLOWS TWICE
	JSR	PC,(PC)		; NO, I MEAN 4 TIMES
	MOVB	(R1)+,R0	; GET CHARACTER
	ROR	R2		; TEST A BIT
	BCC	D.RTS2		; BRANCH IF NOT ON
	JMP	D.TYPE		; TYPE IT AND RETURN

D.N3:	BIC	#177770,R0	; MASK OUT ALL BUT LOW 3 BITS
D.N6:	BIC	#177700,R0	; MASK OUT ALL BUT LOW 6 BITS
D.N8:	BIC	#177400,R0	; MASK OUT ALL BUT LOW 8 BITS
	JMP	D.TYPN		; TYPE THE NUMBER
D.RN6:	MOV	R0,-(SP)	; SAVE R0
	MOV	R4,R0		; GET FIRST PARAMETER
	JSR	PC,D.R		; TYPE AS REGISTER
	MOV	#',,R0		; INSERT COMMA BETWEEN PARAMETERS
	JSR	PC,D.TYPE	; TYPE IT
	MOV	(SP)+,R0	; GET SECOND PARAMETER
	BIC	#^C77,R0	;MASK ALL BUT OFFSET
	NEG	R0		;NEGATE IT
D.X8:	MOVB	R0,R0		; SIGN EXTEND
	ASL	R0		; MULTIPLY BY 2
	BR	D.N17		; DO THE REST AND RETURN
D.RDD:	MOV	R0,-(SP)	; SAVE SECOND PARAMETER
	MOV	R4,R0		; GET FIRST ONE
	JSR	PC,D.R		; TYPE AS A REGISTER
D.SS:	MOV	#',,R0		; PUT COMMA...
	JSR	PC,D.TYPE	; ... INBETWEEN PARAMETERS
	MOV	(SP)+,R0	; GET SECOND PARAMETER

D.DD:				; THIS ROUTINE TYPES A MODE/REGISTER OPERAND IN R0
	MOV	R0,R3		; LOW 6 BITS OF R0 HAVE MODE/REG
	BIC	#177770,R3	; R3 HAS REGISTER
	ASR	R0		; GET MODE
	ASR	R0		; BY SHIFTING
	ASR	R0		; INTO LOW BITS
	BIC	#177770,R0	; R0 HAS MODE
	CMP	R3,#7		; PC ADDRESSING?
	BEQ	D.DC7		; BRANCH IF SO
D.DC50:	MOV	R0,-(SP)	; MAKE THIS SAVED DATA
	MOV	R0,R1		; PUT IN R1 FOR D.DC5
	ADD	#D.OPCH,R1	; ADD IN DISPLACEMENT OF SPECIAL CHARACTERS
	JSR	PC,D.DC5	; TYPE PRECEDING CHARACTERS
	MOV	R3,-(SP)	; SAVE R3
	CMP	R0,#6		; IS THERE AN INDEX?
	BLT	D.DC8		; BRANCH IF NOT
	MOV	(R5)+,R0	; PUT ADDRESS IN R0
	JSR	PC,D.RFND	; TYPE ADDRESS AND OFFSET
	MOV	#'(,R0		; PUT "(" IN OUTPUT
	JSR	PC,D.TYPE	; TYPE IT
D.DC8:	MOV	(SP)+,R0	; GET REGISTER
	JSR	PC,D.R		; TYPE REGISTER NUMBER
	MOV	(SP)+,R1	; RESTORE MODE
	ADD	#D.CLOS,R1	; ADD IN CLOSING CHARACTERS

D.DC5:				; THIS ROUTINE TYPES A STRING INDEXED BY R1
	MOV	R0,-(SP)	; SAVE R0
	MOVB	(R1)+,R2	; GET OFFSET OF CHARACTERS
D.DC62:	MOVB	D.FIRS(R2),R0	; GET CHARACTER
	BEQ	D.DC4		; SKIP IF NULL CHARACTER
	JSR	PC,D.TYPE	; TYPE IT
D.DC4:	INC	R2		; NEXT CHARACTER
	CMPB	R2,(R1)		; AT END?
	BLO	D.DC62		; BRANCH IF NOT
	MOV	(SP)+,R0	; RETURN R0
D.RTS2:	RTS	PC		; RETURN

D.DDR:	MOV	R4,-(SP)	; SAVE FIRST PARAMETER
	JSR	PC,D.DD		; TYPE SECOND PARAMETER
	MOV	#',,R0		; COMMA
	JSR	PC,D.TYPE	; TYPE IT
	MOV	(SP)+,R0	; RESTORE REGISTER

D.R:				; THIS ROUTINE TYPES A REGISTER
	BIC	#177770,R0	; CLEAR HIGH BITS
	CMP	R0,#6		; R5 OR LOWER?
	BLO	D.DC9		; BRANCH IF SO
	BHI	D.DC19		; BRANCH IF PC
	MOV	#D.SP,R1	; "SP"
	BR	D.DC5		; TYPE IT AND RETURN

D.DC19:	MOV	#D.SP+1,R1	; "PC"
	BR	D.DC5		; TYPE IT AND RETURN
D.DC9:	MOV	R0,-(SP)	; SAVE R0
	MOV	#'R,R0		; "R"
	JSR	PC,D.TYPE	; TYPE IT
	MOV	(SP)+,R0	; RESTORE R0
	ADD	#60,R0		; ASCIIZE IT
	JMP	D.TYPE		; TYPE IT AND RETURN
; INSTRUCTION DECODE/ENCODE TABLE

	.MACRO	INSTRS
; THE FIVE PARAMETERS TO THE CODE OP-CODE DESCRIBE AN INSTRUCTION:
; THE FIRST PARAMETER IS THE LOWER LIMIT OF VALUES THAT WILL FALL
;  INTO THAT OP-CODE (THE TABLE MUST BE SCANNED SEQUENTIALLY)
; THE SECOND PARAMETER IS THE OP-CODE TEXT
; THE THIRD PARAMETER TELLS THE MACHINE SUITABILITY
;  0 MEANS ANY MACHINE HAS THIS INSTRUCTION.  1 MEANS
;  11/40 AND UP ONLY, 2 MEANS 11/45 ONLY.
; THE FOURTH PARAMETER TELLS HOW TO DECODE THE PARAMETERS:
;   0 MEANS NO PARAMETERS
;   1 MEANS "NNNNNN" (16 BIT NUMBER)
;   2 MEANS DECODE CONDITION CODE BITS (NZVC)
;   3 MEANS "N" (3 BIT NUMBER)
;   4 MEANS "XXX" (8 BIT DISPLACEMENT)
;   5 MEANS "R,DD"
;   6 MEANS "NN" (6 BIT NUMBER)
;   7 MEANS "SS,DD" (OR "DD,SS")
;  10 MEANS "R"
;  11 MEANS "R,NN" (6 BIT DISPLACEMENT)
;  12 MEANS "NNN" (8 BIT NUMBER)
;  13 MEANS "DD" (OR "SS")
;  14 MEANS "SS,R"
; THE FIFTH PARAMETER IS 1 IF THIS INSTRUCTION IS LEGAL IN BYTE MODE
	CODE	0,HALT,0,0,0
	CODE	1,WAIT,0,0,0
	CODE	2,RTI,0,0,0
	CODE	3,BPT,0,0,0
	CODE	4,IOT,0,0,0
	CODE	5,RESET,0,0,0
	CODE	6,RTT,1,0,0
	CODE	7,,0,1,0
	CODE	100,JMP,0,13,0
	CODE	200,RTS,0,10,0
	CODE	210,,0,1,0
	CODE	230,SPL,2,3,0
	CODE	240,NOP,0,0,0
	CODE	241,CL,0,2,0
	CODE	257,CCC,0,0,0
	CODE	260,,0,1,0
	CODE	261,SE,0,2,0
	CODE	277,SCC,0,0,0
	CODE	300,SWAB,0,13,0
	CODE	400,BR,0,4,0
	CODE	1000,BNE,0,4,0
	CODE	1400,BEQ,0,4,0
	CODE	2000,BGE,0,4,0
	CODE	2400,BLT,0,4,0
	CODE	3000,BGT,0,4,0
	CODE	3400,BLE,0,4,0
	CODE	4000,JSR,0,5,0
	CODE	5000,CLR,0,13,1
	CODE	5100,COM,0,13,1
	CODE	5200,INC,0,13,1
	CODE	5300,DEC,0,13,1
	CODE	5400,NEG,0,13,1
	CODE	5500,ADC,0,13,1
	CODE	5600,SBC,0,13,1
	CODE	5700,TST,0,13,1
	CODE	6000,ROR,0,13,1
	CODE	6100,ROL,0,13,1
	CODE	6200,ASR,0,13,1
	CODE	6300,ASL,0,13,1
	CODE	6400,MARK,1,6,0
	CODE	6500,MFPI,1,13,0
	CODE	6600,MTPI,1,13,0
	CODE	6700,SXT,1,13,0
	CODE	7000,,0,1,0
	CODE	10000,MOV,0,7,1
	CODE	20000,CMP,0,7,1
	CODE	30000,BIT,0,7,1
	CODE	40000,BIC,0,7,1
	CODE	50000,BIS,0,7,1
	CODE	60000,ADD,0,7,0
	CODE	70000,MUL,1,14,0
	CODE	71000,DIV,1,14,0
	CODE	72000,ASH,1,14,0
	CODE	73000,ASHC,1,14,0
	CODE	74000,XOR,1,5,0
	CODE	75000,FADD,1,10,0
	CODE	75010,FSUB,1,10,0
	CODE	75020,FMUL,1,10,0
	CODE	75030,FDIV,1,10,0
	CODE	75040,,0,1,0
	CODE	77000,SOB,1,11,0
	CODE	100000,BPL,0,4,0
	CODE	100400,BMI,0,4,0
	CODE	101000,BHI,0,4,0
	CODE	101400,BLOS,0,4,0
	CODE	102000,BVC,0,4,0
	CODE	102400,BVS,0,4,0
	CODE	103000,BCC,0,4,0
	CODE	103000,BHIS,0,4,0
	CODE	103400,BCS,0,4,0
	CODE	103400,BLO,0,4,0
	CODE	104000,EMT,0,12,0
	CODE	104400,TRAP,0,12,0
	CODE	105000,,0,1,0
.IIF DF,D.LSI,CODE	106400,MTPS,1,13,0
	CODE	106500,MFPD,2,13,0
	CODE	106600,MTPD,2,13,0
.IIF NDF,D.LSI,CODE	106700,,0,1,0
	.IF	DF,D.LSI
	 CODE	106700,MFPS,1,13,0
	 CODE	107000,,0,1,0
	.ENDC
	CODE	160000,SUB,0,7,0
	CODE	170000,,0,1,0
	CODE	177777,,0,1,0
	.ENDM
; WORD ALIGNED CONSTANTS

D.UADD:	D.WULF			;  UW  WULF COMMAND
	D.ONES			;  UT  SINGLE STEP MODE
.IIF DF,D.GDP,D.GRAP		;  UG  RETURN USER DISPLAY
D.LGDR:				; COMMAND DISPATCH TABLE
	D.ERR			;  @  ERROR
	D.ERR			;  #  ERROR
	D.ERR			;  (  ERROR
	D.ADD			;  +   
	D.ADD			;  <SP>
	D.MULT			;  *  MULTIPLICATION
	D.DIV			;  '  DIVISION
	D.SUBT			;  -  SUBTS SIGN
	D.ERR			;  )  ERROR
	D.TEXT			;  "  MAKE ASCII
	D.LWAS			;  >
	D.FWAS			;  <  SET FIRST WORD OF SEARCH
	D.EQAL			;  =  
	D.ALTM			;  $  ALTMODE
	D.COLN			;  :  DEFINES SYMBOL
	D.SEMI			;  ;  RE-TYPE WORD
	D.WRD			;  /  OPEN WORD
	D.BKSL			;  \  STORE AND REFERENCE
	D.DCOM			;  ,  COMMA PARAMETER
	D.CRET			;  <CR>  CLOSE
	D.OP1			;  <LF>  MODIFY, CLOSE, OPEN NEXT
	D.ORPC			;  _  TYPE WORD AS INSTRUCTION
	D.BACK			;  ^  OPEN PREVIOUS
.IIF DF,D.GDP,D.SOFT		;  <CALL>  SOFT RESTART AT 1004
	D.ORAB			;  <TAB>  OPEN RELATED, ABSOLUTE
	D.OPBR			;  [  OPEN WORD AS NUMERIC
	D.CLBR			;  ]  OPEN WORD AS INSTRUCTION
	D.EXCL			;  !  OPEN WORD SILENTLY
	D.ERR			;  <SP> SECOND SPACE (ERROR)
	D.ABS			;  A  ABSOLUTE ADDRESSES
	D.BKPT			;  B  BREAKPOINTS
	D.INNM			;  C  IN NUMERICS
	D.DELE			;  D  KILL LAST SYMBOL
	D.EFF			;  E  SEARCH EFFECTIVE ADDRESS
	D.ERR			;  F  ERROR
	D.GO			;  G  GO TO ADDRESS K
	D.INHA			;  H  IN HALF WORDS
	D.ALTI			;  I  STATUS ADDRESS
	D.ERR			;  J  ERROR
	D.KILL			;  K  SYMBOL TABLE DELETION
	D.ERR			;  L  ERROR
	D.MAST			;  M  SET MASK
	D.NSCH			;  N  NON-SEARCH
	D.BYTE			;  O  TYPEOUT IN BYTES
	D.PROC			;  P  PROCEED
	D.ALTQ			;  Q  CURRENT WORD
	D.INRD			;  R  SET RADIX
	D.INMD			;  S  IN INSTRUCTION MODE
	D.INTX			;  T  IN TEXT
	D.SNGL			;  U  SECOND SET OF ROUTINES
	D.ALTV			;  V  SWAB OF CURRENT WORD
	D.WSCH			;  W  SEARCH WORD
	D.EXEC			;  X  EXECUTE INSTRUCTION
	D.ERR			;  Y  ERROR
	D.ZERO			;  Z  ZERO CORE
D.PARM:	D.RTS
	D.N16
	D.CZVN
	D.N3
	D.X8
	D.RDD
	D.N6
	D.SSDD
	D.R
	D.RN6
	D.N8
	D.DD
	D.DDR
D.PARG:	D.NONE			; NO PARAMETERS
	D.NONE			; 16-BIT NUMBER NOT AN INSTRUCTION
	D.NONE			; CONDITION CODE ALREADY DECODED
	D.NONE			; 3 BIT OPERAND ADDED IN AUTOMATICALLY
	D.DISP			; GET 8-BIT DISPLACEMENT
	D.GRSS			; GET "R,SS"
	D.GNUM			; GET 6-BIT NUMBER (MARK OPERAND)
	D.GSD			; GET "SS,DD"
	D.GR			; GET "R"
	D.GRNN			; GET "R,NN"
	D.GNUM			; GET 8-BIT OPERAND
	D.GDD			; GET "DD" (OR "SS")
	D.GDDR			; GET "DD,R"

	.MACRO	CODE	TOP,STR,LEG,PARM,BYT
	.WORD	TOP-1
	.ENDM
D.TOPS:	INSTRS
	.WORD	-1

	.MACRO	CODE	TOP,STR,LEG,PARM,BYT
	.BYTE	<BYT*200>+<PARM*4>+LEG
	.NCHR	D.LEN,STR
	D.ADDR=D.ADDR+D.LEN
	.BYTE	D.ADDR
	.ENDM
	D.ADDR=0
D.COUS:	.BYTE	D.ADDR
D.LEGS:	INSTRS
D.ECNT=.-1

	.MACRO	CODE	TOP,STR,LEG,PARM,BYT
	.ASCII	"STR"
	.ENDM
D.STRS:	INSTRS
; BYTE ALIGNED CONSTANTS

D.FIRS:	.ASCII	<0> "((@(-(@-(" <0> "@" <0> "))+)+))))??#@#??" <0> "@SPPC"
D.NZVC:	.ASCII	"CVZN"
D.OPCH:	.BYTE	0,1,2,3,5,7,12,13
D.CLOS:	.BYTE	14,15,16,20,22,23,24,25
D.MOD7:	.BYTE	26,27,30,31,33,34,35,36
D.SP:	.BYTE	37,41,43
;D.GRET:	.ASCII	"DDT EXECUTION"
;.IIF NDF,D.GDP,.ASCII "; MANUAL RESTART = "
D.GRET:	.ASCII	"DDT-11"
D.GRND	=.-1
D.BE:	.ASCII	";BPT!"
D.NM:	.ASCII	";NXM!"
D.IM:	.ASCII	";ILG!"
D.UTAB:	.BYTE	'W		;  W
	.BYTE	'T		;  T
.IIF DF,D.GDP,.BYTE 'G		;  G
D.ENUT	=.-D.UTAB
D.LGCH:				; FIRST CHARACTERS MUST BE "@#(+ *'-)"
	.BYTE	'@		;  @
D.HASH	=.-D.LGCH
	.BYTE	'#		;  #
D.OPAR	=.-D.LGCH
	.BYTE	'(		;  (
D.ADDS	=.-D.LGCH
	.BYTE	'+		;  +
D.SPAC	=.-D.LGCH
	.BYTE	' 		;  <SP>
	.BYTE	'*		;  *
	.BYTE	''		;  '
D.DASH	=.-D.LGCH
	.BYTE	'-		;  -
D.CPAR	=.-D.LGCH
	.BYTE	')		;  )
	.BYTE	'"		;  "
	.BYTE	'>		;  >
	.BYTE	'<		;  <
	.BYTE	'=		;  =
	.BYTE	33		;  <ALT>
D.COLO	=.-D.LGCH
	.BYTE	':		;  :
	.BYTE	';		;  ;
	.BYTE	'/		;  /
	.BYTE	'\		;  \
D.COMM	=.-D.LGCH
	.BYTE	',		;  ,
D.CR:	.BYTE	15		;  <CR>
	.BYTE	12		;  <LF>
	.BYTE	'_		;  _
	.BYTE	'^		;  ^
.IIF DF,D.GDP,.BYTE	3	;  <CALL>
	.BYTE	11		;  <TAB>
	.BYTE	'[		;  [
	.BYTE	']		;  ]
	.BYTE	'!		;  !
D.LETR	=.-D.LGCH
D.RDTB:	.ASCII	" ABCDEFGHIJKLMNOPQRSTUVWXYZ"
D.CLGT	=.-D.LGCH		; COMMAND TABLE END
	.ASCII	"$.*0123456789"
D.ENTB	=.-D.RDTB
; BYTE ALIGNED VARIABLES

	.IF	DF,D.KSR
D.CPOS:	 .BYTE	71.		; CHARACTER POSITION FOR TTY
D.BUFR:	 .BLKB	25.		; 25 CHARACTER INPUT BUFFER
D.ENDB:
	.ENDC
D.USED:	.BYTE	0		; IF ZERO, USE OCTAL NUMBER
D.MACH:	.BYTE	1		; 0=11/15  1=11/40  2=11/45
D.LEVL:	.BYTE	0		; PARENTHESIS LEVEL
D.FWAF:	.BYTE	0		; MARKER OF < PARAMETER
D.INPA:	.BYTE	0		; NON-ZERO IF IN AN INSTRUCTION TYPE-IN
D.P:	.BYTE	-1		; PROCEED FLAG = <1-8>*2 IF NORMAL BREAK
				;		0 IF SINGLE STEP BREAK
				;		-1 IF NOT ENTERED BY BREAK
D.ALTF:	.BYTE	0		; ALTMODE FOUND
D.WAMS:	.ASCII	";  WORDS"
D.BMES:	.ASCII	"$ B >> "
; WORD ALIGNED VARIABLES
	.EVEN

	.IF	DF,D.KSR
D.INPU:	 D.BUFR			; INPUT BUFFER POINTER
D.OUTP:	 D.BUFR			; OUTPUT BUFFER POINTER
	.ENDC
D.SYM:	.BLKW	<D.SYML+1>/2	; HOLDS SYMBOL TYPED
D.SD.T:				; WORD ADDRESS OF D.S AND D.T
D.S:	.BYTE	0		; SINGLE STEP FLAG
D.T:	.BYTE	0		; T-BIT FLAG
D.BOTH:				; WORD ADDRESS OF D.NOTY AND D.FIND
D.NOTY:	.BYTE	0		; DON'T TYPE OUT IF EQUALS 1
D.FIND:	.BYTE	0		; ADDRESS FOUND (EFF SEARCH) IF EQUALS 1
D.TPC:	0			; PC OF LAST BPT WE PROCEEDED
D.LFIN:	0			; LINE FEED INCREMENT
; THE NEXT 4 WORDS FORM THE TEMPORARY MODE TABLE AND MUST BE IN ORDER********
D.CURM:	D.INST			; TYPEOUT MODE ADDRESS			*****
D.DVTB:	8.			; CURRENT RADIX				*****
D.BW:	2			; BYTE-WORD INDICATOR (1=BYTE, 2=WORD)	*****
D.IFMT:	0			; (1=ABSOLUTE, 0=RELATIVE)		*****
; END OF CRITICAL ORDERING***************************************************
; THE NEXT 4 WORDS FORM THE PERMANENT MODE TABLE AND MUST BE IN ORDER********
D.PERM:	D.INST			; PERMANENT TYPEOUT MODE		*****
D.PERN:	8.			; PERMANENT RADIX			*****
D.PEBW:	2			; PERMANENT BYTE-WORD INDICATOR		*****
D.PEFM:	0			; PERMANENT ADDRESS TYPEOUT INDICATOR	*****
; END OF CRITICAL ORDERING***************************************************
D.OMOD:	D.INST			; MODE TO OPEN WORDS IN
D.OPER:	0			; OPERATION
D.DECN:	0			; DECIMAL NUMBER
D.SVR2:	0			; SAVE FOR R2
; THE NEXT THREE LINES MUST BE IN THAT ORDER FOR $X INST.********************
D.SVR4:	0			; SAVE FOR R4				*****
D.PARS:	0,0			; PARAMETERS FOR INSTR. TYPE-IN		*****
	JMP	D.EXE2		; RETURN IN CASE INSTRUCTION FINISHES	*****
; END OF CRITICAL ORDERING***************************************************
D.SVR7:	0			; SAVE FOR PC DURING $X
D.PARO:	0,0			; RELOCATIOON FOR D.PARS
D.OFST:	0			; OFFSET FROM COMMA
D.RFNL:	127.			; RFND OFFSET
D.LASV:	0			; LAST TYPED NUMBER
D.LASW:	0			; LAST TYPED WORD
D.DOT:	0			; CURRENT LOCATION
D.CADC:	0			; COPY OF D.CAD FOR TYPE-IN
D.ERF:	0			; ADDRESS OF ERROR MESSAGE
D.CAD:	0			; CURRENT ADDRESS
D.XXX:	0			; TEMPORARY STORAGE
D.COMA:	0			; ADDRESS BEFORE COMMA
D.SIZE:	0			; BYTE SIZE FOR "O" TYPEOUT
D.RAD1:	0			; FIRST WORD OF RAD50 SYMBOL
D.RAD2:	0			; SECOND WORD OF RAD50 SYMBOL
D.LASC:	0			; LAST COLONED WORD
D.FENC:	D.SYMA			; ADDRESS OF FENCE SYMBOL TABLE
D.POS:	D.SYM			; ADDRESS OF CHARACTER IN D.SYM
D.FWA:	0			; LOW LIMIT
D.LWA:	DDT-2			; HIGH LIMIT
D.MASK:	177777			; MASK

D.BKTB:	.REPT	D.BKP
	0			; ADDRESS OF BREAKPOINTS
	.ENDR
D.CT:	.BLKW	D.BKP+1		; EXTRA LOCATION FOR SINGLE STEP
D.UIN:	.BLKW	D.BKP
D.OPEN:	.BLKW	D.BKP+1		; EXTRA LOCATION FOR SINGLE STEP
; THE DDT STACK, INCLUDING SOME VARIABLES AT ITS BASE (HIGH ADDRESSES)
; WHICH DESCRIBE THE USER'S PROGRAM STATE:

; THE FOLLOWING VARIABLES ARE CRITICALLY ORDERED FOR VARIOUS REASONS.********
	.BLKW	40.		; ACTIVE STACK AREA			*****
D.STK:				; BASE OF ACTIVE DDT STACK		*****
.IIF DF,D.KSR,	0		; SAVE CELL - R C/SR			*****
	0			; SAVE CELL - T C/SR			*****
	0,0,0,0			; USER LOCATION 12,10,6,4		*****
D.UR0:	0			; USER REGISTER 0			*****
D.UR1:	0			; USER REGISTER 1			*****
D.UR2:	0			; USER REGISTER 2			*****
D.UR3:	0			; USER REGISTER 3			*****
D.UR4:	0			; USER REGISTER 4			*****
D.UR5:	0			; USER REGISTER 5			*****
D.UR6:	0			; USER SP				*****
D.UR7:	0			; USER PC				*****
JOBSA:	0			; USER START ADDRESS			*****
; END OF CRITICALLY ORDERED VARIABLES****************************************

D.USTA:	0			; USER STATUS
D.DSTA:	D.PRIO			; DDT'S STATUS

D.SYMA:	.RAD50	/R0    /	; THIS SYMBOL TABLE MUST APPEAR
	D.UR0			; AT THE END OF DDT SINCE IT IS
	.RAD50	/R1    /	; EXTENDED MAGICALLY BY THE LINKER
	D.UR1			; STARTING AT ADDRESS D.SYMT
	.RAD50	/R2    /
	D.UR2
	.RAD50	/R3    /
	D.UR3
	.RAD50	/R4    /
	D.UR4
	.RAD50	/R5    /
	D.UR5
	.RAD50	/SP    /
	D.UR6
	.RAD50	/PC    /
	D.UR7
D.SYMT:	0,0			; TABLE TERMINATED BY NULL SYMBOL NAME

.ENDC
.IIF NE END$$,	.END