.NOBIN

	.TOC	"PAGE FAIL REFIL LOGIC"



;WHEN THE CPU CAN NOT COMPLETE A MEMORY REFERENCE BECAUSE THE PAGE

; TABLE DOES NOT CONTAIN VALID INFORMATION FOR THE VIRTUAL PAGE INVOLVED

; THE HARDWARE CALLS THIS ROUTINE TO RELOAD THE HARDWARE PAGE TABLE.

;

;THIS CODE WILL EITHER DO THE RELOAD OR GENERATE A PAGE FAIL FOR THE

; SOFTWARE. THE INFORMATION LOADED CONSISTS OF THE PHYSICAL PAGE NUMBER,

; THE CACHE ENABLE BIT AND THE WRITE ENABLE BIT.



;THIS LOGIC USES MANY VARIABLES. THEY ARE DESCRIBED BRIEFLY HERE:



;THING			WHERE KEPT			USE

;OLD VMA		WORKSPACE WORD 210		SAVES VMA

;OLD AR 		WORKSPACE WORD 211		SAVES AR

;OLD ARX		WORKSPACE WORD 212		SAVES ARX

;OLD BR 		WORKSPACE WORD 213		SAVES BR

;OLD BRX		WORKSPACE WORD 214		SAVES BRX

;KL PAGING BIT		EBR BIT 1 (IN 2901)		INDICATES KL STYLE (TOPS-20) PAGING

;							INSTEAD OF KI STYLE (TOPS-10 AND DIAGNOSTIC)

;							MODE PAGING

;W BIT			FLG BIT 4			PAGE CAN BE WRITTEN

;C BIT			FLG BIT 6			DATA IN THIS PAGE MAY BE PUT

;							INTO CACHE

;PI CYCLE		FLG BIT 5			STORING OLD PC DURING PI

;MAP FLAG		FLG BIT 18			MAP INSTRUCTION IN PROGRESS

;CLEANUP CODE		FLG BITS 32-35			WHAT TO DO SO INSTRUCTION MAY BE

;							RESTARTED

;SPT BASE		WORKSPACE WORD 215		ADDRESS OF SHARED-POINTER-TABLE

;CST BASE		WORKSPACE WORD 216		ADDRESS OF CORE-STATUS-TABLE

;CST MASK		WORKSPACE WORD 217		BITS TO KEEP ON CST UPDATE

;CST DATA (PUR) 	WORKSPACE WORD 220		BITS TO SET ON CST UPDATE

;PAGE TABLE ADDRESS	AR				WHERE THIS PAGE TABLE IS LOCATED

;PHYSICAL PAGE # (PPN)	AR				RESULT OF THIS PROCESS

;CST ENTRY		AR				CORE STATUS TABLE ENTRY

;SPT ENTRY		AR				WORD FROM SPT

;PAGE TABLE ENTRY	AR				WORD FROM PT

;PAGE NUMBER		BR				INDEX INTO CURENT PAGE TABLE

;PAGE FAIL WORD 	BRX				WHAT HAPPENED (ALSO MAP RESULT)



.IF/INHCST

	SKIP NO CST	"AD/D,DBUS/RAM,RAMADR/#,WORK/CBR,DT/4T,SKIP/ADEQ0"

.ENDIF/INHCST

;

;

;

;		   KL10 PAGING - WORD FORMATS

;

;Section Pointer

;

;The section pointer is found in the user or exec section table.

;(Part of UPT or EPT.)

;

;Section pointer provides (via the SPT) the physical address  of

;the PAGE TABLE for the given section.

;

;	 Code:	 0	 No-access (trap)

;		 1	 Immediate

;		 2	 Share

;		 3	 Indirect

;		 4-7	 Unused, reserved

;

;	 0 1 2 3 4 5 6		 18			 35

;	 +----+-+-+-+-+---------+-------------------------+	

;	 !CODE!P!W! !C!/////////!  PAGE TABLE IDENTIFIER  !

;	 !010 ! ! ! ! !/////////!	 (SPT INDEX)	  !

;	 +----+-+-+-+-+---------+-------------------------+

;

;		NORMAL SECTION POINTER (Code = 2)

;

;	 0   2 3 4 5 6	   9	       18		      35

;	 +----+-+-+-+-+---+-----------+------------------------+

;	 !CODE!P!W! !C!///!SECTION    !SECTION TABLE IDENTIFIER!

;	 !011 ! ! ! ! !///!TABLE INDEX!       (SPT INDEX)      !

;	 +----+-+-+-+-+---+-----------+------------------------+

;

;	       INDIRECT SECTION POINTER (Code = 3)

;PAGE POINTERS

;

;FOUND IN PAGE TABLES

;

;	 0 1 2 3 4 5 6	    12				 35

;	 +----+-+-+-+-+----+------------------------------+

;	 !CODE!P!W! !C!////!   PHYSICAL ADDRESS OF PAGE   !

;	 !001 ! ! ! ! !////!				  !

;	 +----+-+-+-+-+----+------------------------------+

;

;		 IMMEDIATE POINTER (code field = 1)

;

;	 B12-35  give PHYSICAL ADDRESS OF PAGE

;	     if  B12-17 >< 0, page not in core-trap

;	     if  B12-17 =  0, B23-35 give CORE PAGE

;			      NUMBER of page, B18-22 MBZ

;

;

;

;

;

;	 0    2 3     6 	  18			 35

;	 +-----+-------+---------+------------------------+

;	 !CODE !SAME AS!/////////!	  SPT INDEX	  !

;	 !010  ! IMMED.!/////////!			  !

;	 +-----+-------+---------+------------------------+

;

;		 SHARED POINTER (code field = 2)

;

;	 B18-35  Give SPT INDEX (SPTX).  SPTX + SPT BASE

;		 ADDRESS = physical core address of word

;		 holding physical address of page.

;	 0 1 2 3      6     9	 17 18			 35

;	 +----+--------+---+-------+----------------------+

;	 !CODE!SAME AS !///! PAGE  ! PAGE TABLE IDENTIFIER!	

;	 !011 ! IMMED. !///!NUMBER !	 (SPT INDEX)	  !

;	 +----+--------+---+-------+----------------------+

;

;		 INDIRECT POINTER (code field = 3)

;

;	 This pointer type causes another pointer to be  fetched

;	 and  interpreted.   The  new pointer is found in word N

;	 (B9-17) of the page addressed by C(SPT + SPTX).

;

;

;

;	 SPT ENTRY

;

;	 Found in the SPT, i.e., when fetching C(SPT +SPTX)

;

;			       12			 35

;	 +--------------------+---------------------------+

;	 !////////////////////!  PHYSICAL ADDRESS OF PAGE !

;	 !////////////////////! 	 OR PAGE TABLE	  !

;	 +--------------------+---------------------------+

;

;		 B12-35  Give PHYSICAL ADDRESS of page.

;

;	 The base address (physical core  address)  of	the  SPT

;	 resides in one AC of the reserved AC block.

;PHYSICAL STORAGE ADDRESS

;

;Found in B12-35 of IMMEDIATE POINTERS and SPT ENTRIES.

;

;			 12	 17 18	 23		 35

;			 +---------+----+-----------------+

;			 !	   !MBZ ! CORE PAGE NUMBER!

;			 !	   !	!   IF B12-17 = 0 !

;			 +---------+----+-----------------+

;

;	 If B12-17 = 0, then B23-35 are CORE PAGE NUMBER  (i.e.,

;	 B14-26  of  physical  core  address) of page and B18-22

;	 MBZ.  If B12-17 >< 0, then  address  is  not  core  and

;	 pager traps.

;

;

;

;CORE STATUS TABLE ENTRY

;

;Found when fetching C(CBR + CORE PAGENO)

;

;	 0	5				  32  34 35

;	 +-------+-------------------------------+------+-+

;	 !  CODE !				 !	!M!

;	 +-------+-------------------------------+------+-+

;

;	 B0-5	 are code field:

;

;		 0 - unavailable, trap

;

;		 1-77 - available

;

;

;

;	 B32-34 reserved for future hardware specification.

;

;	 B35 is "modified" bit, set on any write ref to page.

;QUANTITIES IN HARDWARE REGISTERS

;

;SPT	 SPT Base Register

;

;			 14				 35

;			 +--------------------------------+

;			 !   PHYSICAL CORE WORD ADDRESS   !

;			 +--------------------------------+

;

;CBR	 CST Base Register

;

;			 14				 35

;			 +--------------------------------+

;			 !   PHYSICAL CORE WORD ADDRESS   !

;			 +--------------------------------+

;

;CSTMSK  CST Update Mask

;

;	 0					     32  35

;	 +------------------------------------------+---+-+

;	 !			 MASK		    !111!1!

;	 +------------------------------------------+---+-+

;

;		 ANDed with CST word during update

;

;(B32-35 must be all 1's to preserve existing CST information)

;

;CSTDATA CST Update Data

;

;	 0				      32 34 35	

;	 +------------------------------------------+---+-+

;	 !			 DATA		    !000!0!

;	 +------------------------------------------+---+-+

;

;		 IORed with CST word during update

;

;(B32-35 must be all 0's to preserve existing CST information)

;

;All  unspecified  bits  and  fields  are  reserved  for  future

;specification by DEC.

;

	.BIN



	.DCODE

257:	IOT,	AC,	J/MAP

	.UCODE



1553:

MAP:	[AR]_[AR].OR.#,		;ASSUME PHYSICAL REF

	#/160000,		;FAKE ANSWER

	HOLD RIGHT		; ..

	[BRX]_VMA		;PUT VMA AND FLAGS IN BRX

	[BRX]_[BRX].AND.#,	;JUST KEEP USER BIT

	#/400000, HOLD RIGHT	; ..

	WORK[SV.VMA]_[BRX]	;SAVE IN WORKSPACE

	[BR]_WORK[APR]		;GET APR FLAGS

	TR [BR], #/030000	;PAGING ENABLED?

=0	STATE_[MAP], J/PFMAP	;YES--DO REAL MAP

	AC_[AR], NEXT INST	;NO--RETURN VIRTUAL ADDRESS

;HARDWARE COMES HERE ON PAGE TABLE NOT VALID (OR INTERRUPT) WHEN

; STARTING A MEMORY REFERENCE. MICOWORD ADDRESS OF INSTRUCTION DOING

; MEM WAIT IS SAVED ON THE STACK.

3777:

PAGE-FAIL:

	WORK[SV.AR]_[AR]

ITRAP:	WORK[SV.BRX]_[BRX]

	[BRX]_VMA

	WORK[SV.VMA]_[BRX]

	WORK[SV.ARX]_[ARX],

	SKIP IRPT		;SEE IF INTERRUPT (SAVE DISPATCH)

=0000

PFD:	DBM/PF DISP, DBUS/DBM,	;BRING CODE TO 2901'S

	AD/D, DEST/PASS, 4T,	;PUT ON DP 18-21

	DISP/DP LEFT, J/PFD	;DISPATCH ON IT

=0001				;(1) INTERRUPT

	WORK[SV.BR]_[BR], J/PFPI1

=0011				;(3) BAD DATA FROM MEMORY

	[BRX]_IO DATA,		;GET THE BAD DATA

	AD PARITY OK/0,		; DO NOT LOOK AT PARITY

	J/BADDATA		;SAVE IN AC BLK 7

=0101				;(5) NXM ERROR

	[BRX]_[370000] XWD 0, J/HARD

=0111				;(7) NXM & BAD DATA

	[BRX]_[370000] XWD 0, J/HARD

=1000				;(10) WRITE VIOLATION

	WORK[SV.BR]_[BR], J/PFMAP

=1001				;[123] (11) 1 ms timer and movsrj

	WORK[SV.BR]_[BR], J/PFPI1

=1010				;(12) PAGE NOT VALID

	WORK[SV.BR]_[BR], J/PFMAP

=1011				;(13) EXEC/USER MISMATCH

	WORK[SV.BR]_[BR], J/PFMAP

=



BADDATA:

	WORK[BADW0]_[BRX]	;SAVE BAD WORD

	WORK[BADW1]_[BRX]	;AGAIN

	[BRX]_[360000] XWD 0, J/HARD

;WE HAVE SAVED AR, ARX, BR AND BRX. WE MERGE IN HERE FROM MAP

; INSTRUCTION, SAVE THE VMA AND START THE PAGE FAIL WORD.

PFMAP:	ABORT MEM CYCLE		;CLEAR PAGE FAIL

	[FLG]_[FLG].OR.#,	;PRESET W AND C TO 1

	FLG.W/1, FLG.C/1,	;BITS INVOLVED

	HOLD RIGHT		;LEAVE RH ALONE

	TL [BRX], WRITE TEST/1	;IS THIS A WRITE TEST?

=0	[BRX]_[BRX].OR.#,

	#/10000,

	HOLD RIGHT		;YES--TURN INTO WRITE REF

	[BRX]_[BRX].AND.#,	;START PAGE FAIL WORD

	#/411000,		;SAVE 3 INTERESTING BITS

	HOLD RIGHT		;SAVE VIRTUAL ADDRESS

				;USER ADDR (400000)

				;WRITE REF (010000)

				;PAGED REF (001000)

	[BRX]_[BRX].XOR.#,	;FIX BIT 8

	#/1000, HOLD RIGHT

	[BR]_[BRX],		;COPY VIRTUAL ADDRESS

	SC_7			;PREPARE TO SHIFT 9 PLACES

=0

PF25:	[BR]_[BR]*.5,		;RIGHT ADJUST PAGE #

	STEP SC,		;COUNT SHIFT STEPS

	J/PF25			;LOOP FOR 9

	[BR]_[BR].AND.# CLR LH,	;MASK TO 9 BITS

	#/777			; ..

.IF/KLPAGE

.IF/KIPAGE

	TL [EBR],		;KI MODE REFILL?

	#/40			;FLAG BIT

=0

.ENDIF/KIPAGE

	READ [BRX],		;USER REF? (KL MODE)

	SKIP DP0,		; ..

	J/PF30			;CONTINUE AT PF30

.ENDIF/KLPAGE

.IF/KIPAGE

	[ARX]_[BR]*.5,		;KI10 MODE REFILL

	J/KIFILL		;GO HANDLE EASY CASE

.ENDIF/KIPAGE

.IF/KLPAGE

;HERE IN TOPS-20 MODE

;PICK UP CORRECT SECTION POINTER

=0

PF30:	[ARX]_WORK[PTA.E],	;EXEC MODE

	SKIP AD.EQ.0, 4T,	;SEE IF VALID

	J/PF35			;CONTINUE BELOW

	[ARX]_WORK[PTA.U],	;USER MODE

	SKIP AD.EQ.0, 4T	;SEE IF VALID

=0	VMA_[ARX]+[BR],		;POINTER VALID

	VMA PHYSICAL READ,	;START MEMORY

	J/PF77			;CONTINUE BELOW

	[AR]_[UBR]+#, 3T,	;USER MODE

	#/540,			;OFFSET TO UPT

	J/PF40			;GO GET POINTER



=0

PF35:	VMA_[ARX]+[BR],		;POINTER VALID

	VMA PHYSICAL READ,	;START MEMORY

	J/PF77			;CONTINUE BELOW

	[AR]_[EBR]+#, 3T,	;EXEC MODE

	#/540			;OFFSET TO EPT

PF40:	VMA_[AR],		;LOAD THE VMA

	START READ,		;START THE MEMORY CRANKING

	VMA PHYSICAL		;ABSOLUTE ADDRESS

	MEM READ,		;WAIT FOR MEMORY

	[AR]_MEM		;POINT POINTER IN AR

;LOOK AT SECTION POINTER AND DISPATCH ON TYPE

=000

PF45:	SC_7,			;FETCH SECTION 0 POINTER

	CALL [SETPTR]		;FIGURE OUT POINTER TYPE

SECIMM:	TL [AR],		;IMMEDIATE POINTER

	#/77,			;TEST FOR 12-17 = 0

	J/PF50			;CONTINUE AT PF50

	[AR]_[AR]+WORK[SBR],	;SHARED SECTION

	J/SECSHR		;GO FETCH POINTER FROM SPT

	[AR]_[AR]+WORK[SBR],	;INDIRECT SECTION POINTER

	CALL [RDPT]		;GO FETCH SPT ENTRY

=111	TL [AR],		;12 TO 17 = 0?

	#/77			; ..

=

=0	PAGE FAIL TRAP		;NO

	[AR]_[AR]*2,		;FIRST SHIFT

	STEP SC			;SC WAS LOADED AT PF45

=0*0

PF60:	[AR]_[AR]*2,		;CONVERT TO ADDRESS OF

	STEP SC,		; SECTION TABLE

	J/PF60

	CALL [RDPT]		;READ SECTION TABLE

=1*1	J/PF45			;TRY AGAIN

=

;STILL .IF/KLPAGE

;HERE FOR SHARED SECTION. AR GETS THE ADDRESS OF PAGE TABLE

=0**

SECSHR:	CALL [RDPT]		;READ WORD FROM SPT

	TL [AR], #/77		;TEST FOR BITS 12-17 = 0



;HERE WITH ADDRESS OF PAGE TABLE IN AR AND SKIP ON

; BITS 12 THRU 17 EQUAL TO ZERO

=0

PF50:	PAGE FAIL TRAP		;BITS 12-17 .NE. 0

	[ARX]_[AR].AND.# CLR LH, ;PAGE NUMBER OF PAGE TABLE

	#/3777			;11 BIT PHYSICAL PAGE #

.IFNOT/NOCST

=0*	[AR]_[ARX],		;COPY ADDRESS

	CALL [UPCST]		;UPDATE CST0

PF70:	[AR]_[AR].OR.WORK[PUR]	;PUT IN NEW AGE AND

				; USE BITS

.IFNOT/INHCST

=0**	START NO TEST WRITE,	;START MEMORY WRITE

	CALL [IBPX]		;GO STORE IN MEMORY

.ENDIF/INHCST

.IF/INHCST

=0**	SKIP NO CST,		;SEE IF A CST

	CALL [WRCST]		;AND GO WRITE IN MEMORY

.ENDIF/INHCST

	SC_7			;THIS CAN BE BUMMED

=0

PF75:	[ARX]_[ARX]*2,		;CONVERT PAGE NUMBER TO

	STEP SC,		; PAGE ADDRESS

	J/PF75			;LOOP OVER 9 STEPS

;STILL .IF/KLPAGE

;WE NOW HAVE THE ADDRESS OF THE PAGE TABLE ENTRY. GO

; READ IT AND START ANALYSIS



;IF WE ARE HERE FOR THE FIRST TIME FOR THE USER OR EXEC SAVE THE

; ADDRESS OF THE PAGE TABLE IN PTA.E OR PTA.U SO THAT WE DO NOT

; HAVE TO DO THE SECTION LOOKUP EVERY TIME.

	READ [BRX], SKIP DP0	;USER OR EXEC REF?

=000	[AR]_WORK[PTA.E],	;EXEC MODE

	SKIP AD.EQ.0, 4T,	;SEE IF SET YET

	CALL [SHDREM]		;SHOULD WE REMEMBER PTR

	[AR]_WORK[PTA.U],	;USER MODE

	SKIP AD.EQ.0, 4T,	;SEE IF SET YET

	CALL [SHDREM]		;SHOULD WE REMEMBER PTR

	WORK[PTA.E]_[ARX],	;SAVE FOR EXEC

	J/PF76			;CONTINUE BELOW

	WORK[PTA.U]_[ARX],	;SAVE FOR USER

	J/PF76			;CONTINUE BELOW

=111

PF76:	VMA_[ARX]+[BR], 	;READ PAGE POINTER

	START READ,

	VMA PHYSICAL

=

=00

PF77:	MEM READ,		;START ANALYSIS OF POINTER

	[AR]_MEM,

	CALL [SETPTR]

PTRIMM: TL [AR],		;IMMEDIATE POINTER

	#/77,			;CHECK FOR BITS 0-5

	J/PF80			;GO TO PF80

	[AR]_[AR]+WORK[SBR],	;SHARED POINTER

	J/PTRSHR		;GO TO READ SPT

;STILL .IF/KLPAGE

;INDIRECT POINTER. CHANGE PAGE # AND LOOK FOR PAGE TABLE

PTRIND:	[BR]_[AR] SWAP, 	;PUT IN RIGHT HALF

	SKIP/-1 MS		;DID CLOCK GO OFF

=0	WORK[SV.AR1]_[AR],	;YES--UPDATE CLOCK

	J/PFTICK		; ..

	[BR]_[BR].AND.# CLR LH,	;UPDATE PAGE # AND RESTART

	#/777,			;MASK FOR PAGE #

	SKIP IRPT		;SEE IF THIS IS A LOOP

=0	[AR]_[AR].AND.#,	;CHANGE INDIRECT POINTER

	#/277000,		; INTO SHARE POINTER

	HOLD RIGHT,		; ..

	J/PF45			;GO BACK AND TRY AGAIN

	PAGE FAIL TRAP		;POINTER LOOP



=0**

PTRSHR:	CALL [RDPT]		;GO LOOK AT POINTER

	TL [AR],		;BITS 12-17 .EQ. 0?

	#/77



;HERE WITH FINAL POINTER. SKIP IF 12-17 NOT EQUAL TO ZERO

.IFNOT/NOCST

=00

PF80:	PAGE FAIL TRAP		;NO--TAKE A TRAP

	[ARX]_[AR].AND.# CLR LH, ;SAVE PHYSICAL PAGE #

	#/3777,			;MASK TO 13 BITS

	CALL [UPCST]		;UPDATE CST0

=11

.IF/NOCST

=0

PF80:	PAGE FAIL TRAP		;NO--TAKE A TRAP

.ENDIF/NOCST



;HERE WE HAVE CST ENTRY IN AR, PAGE FAIL WORD IN BRX. GO LOOK

; AT WRITABLE AND WRITTEN BITS

PF90:	[BRX]_[BRX].OR.#,	;TRANSLATION IS VALID

	#/100000, HOLD RIGHT	; ..

	TL [FLG], FLG.W/1	;IS THIS PAGE WRITABLE?

=0	[BRX]_[BRX].OR.#,	;YES--INDICATE THAT IN PFW

	#/020000,

	J/PF100			;NOT WRITE VIOLATION

	TL [BRX],		;IS THIS A WRITE REF?

	WRITE TEST/1, WRITE CYCLE/1

=0	PAGE FAIL TRAP		;WRITE VIOLATION

PF107:

.IFNOT/NOCST

	[AR]_[AR].OR.WORK[PUR],	;PUT IN NEW AGE

	J/PF110			;GO TO STORE CST ENTRY

.ENDIF/NOCST

.IF/NOCST

PFDONE:	TR [FLG],

	#/400000,

	J/PF140

.ENDIF/NOCST



=0*

PFTICK:	[AR]_WORK[TIME1],	;UPDATE TIMER

	SPEC/CLRCLK, CALL [TOCK]

	[AR]_WORK[SV.AR1],	;RESTORE AR

	J/PTRIND		;GO TRY AGAIN

;STILL .IF/KLPAGE

;HERE IF PAGE IS WRITABLE

PF100:	TL [BRX], WRITE CYCLE/1	;IS THIS A WRITE REF?

=0	[AR]_[AR].OR.#, 	;YES--SET WRITTEN BIT

	#/1,

	HOLD LEFT,

	J/PF105

	TR [AR],		;NOT WRITE, ALREADY WRITTEN?

	#/1

=0

PF105:	[BRX]_[BRX].OR.#,	;WRITTEN SET BIT

	#/040000,		;MARK PAGE AS

	HOLD RIGHT,		;WRITABLE

	J/PF107			;STORE CST WORD

	[FLG]_[FLG].AND.NOT.#,	;NOT WRITTEN, CAUSE TRAP ON

	FLG.W/1,		; WRITE ATTEMPT

	HOLD RIGHT,		;ONLY CLEAR LH

	J/PF107

.IFNOT/NOCST

=0**

PF110:

.IFNOT/INHCST

	START NO TEST WRITE,

	CALL [IBPX]		;STORE CST ENTRY

.ENDIF/INHCST

.IF/INHCST

	SKIP NO CST,

	CALL [WRCST]

.ENDIF/INHCST



.ENDIF/KLPAGE



;HERE WHEN WE HAVE FIGURED OUT PHYSICAL ADDRESS (IN ARX) AND FLAGS

; (IN BRX) RELOAD PAGE TABLE.

PFDONE: TR [FLG],		;MAP INSTRUCTION?

	#/400000

.ENDIF/NOCST

=0

PF140:	[AR]_[ARX],		;GET PHYSCIAL PAGE #

	SC_7,			;PREPARE TO CONVERT TO

	J/PF130			; WORD ADDRESS

	[AR]_WORK[SV.VMA],	;RESTORE VMA

	J/PF120

=0

PF130:	[AR]_[AR]*2,		;CONVERT TO WORD #

	STEP SC,

	J/PF130

	[AR]_[AR].AND.#,	;JUST ADDRESS BITS

	#/3,

	HOLD RIGHT

	END MAP 		;CLEAR MAP FLAGS

	[BRX]_[BRX].OR.#,	;TURN ON THE TRANSLATION

	#/100000,		; VALID BIT

	HOLD RIGHT		; IN LEFT HALF ONLY

	TL [FLG], FLG.C/1	;CACHE BIT SET?

=0	[BRX]_[BRX].OR.#,	;YES--SET IN MAP WORD

	#/002000, HOLD RIGHT	; ..

	[BRX]_[BRX].AND.#,	;PRESERVE WORD #

	#/777, HOLD LEFT	; IN PAGE FAIL WORD

	[AR]_[AR].OR.[BRX],	;COMPLETE MAP INSTRUCTION

	EXIT

PF120:	[BR]_[AR]		;COPY PAGE FAIL WORD

	[BR]_[AR].AND.NOT.#,	;CLEAR BITS WHICH START A CYCLE

	READ CYCLE/1,		; ..

	WRITE CYCLE/1,		; ..

	WRITE TEST/1,		; ..

	HOLD RIGHT		;JUST DO LEFT HALF

	VMA_[BR], 3T,		;RESTORE VMA

	DP FUNC/1		;SET USER ACCORDING TO WHAT IT WAS

	[ARX]_[ARX].AND.# CLR LH, ;JUST KEEP PAGE #

	#/3777			; ..

	[BRX]_[ARX].OR.#, #/400000 ;SET VALID BITS

	TL [FLG], FLG.W/1	;WANT WRITE SET?

=0	[BRX]_[BRX].OR.#, #/040000 ;SET WRITE BIT

	TL [FLG], FLG.C/1,	;WANT CACHE SET?

	LOAD PAGE TABLE		;LOAD PAGE TABLE ON NEXT

				; MICRO INSTRUCTION

=0	[BRX]_[BRX].OR.#,	;SET CACHE BIT

	#/020000, J/PF125	;CACHE BIT

	READ [BRX]		;LOAD PAGE TABLE

PF125:	[ARX]_WORK[SV.ARX]

	[BR]_WORK[SV.BR]

	[BRX]_WORK[SV.BRX]

	VMA_[AR],		;MAKE MEM REQUEST

	DP FUNC/1, 3T,		;FROM DATA PATH

	WAIT/1			;WAIT FOR PREVIOUS CYCLE TO

				; COMPLETE. (NEED THIS TO 

				; START ANOTHER CYCLE)

	[AR]_WORK[SV.AR],

	RETURN [0]

.IF/KLPAGE

.IFNOT/NOCST

;SUBROUTINE TO START CST UPDATE

;CALL WITH:

;	AR/ PHYSICAL PAGE NUMBER

;RETURN 2 WITH ENTRY IN AR, PAGE FAIL IF AGE TOO SMALL

.IFNOT/INHCST

=0**

UPCST:	[AR]_[AR]+WORK[CBR],	;ADDRESS OF CST0 ENTRY

	CALL [RDPT]		;READ OLD VALUE

	TL [AR],		;0 - 5 = 0?

	#/770000		; ..

=0	[AR]_[AR].AND.WORK[CSTM],	;CLEAR AGE FIELD

	RETURN [2]		;AGE IS NOT ZERO

	PAGE FAIL TRAP		;AGE TOO SMALL

.ENDIF/INHCST

.IF/INHCST

UPCST:	SKIP NO CST		;SEE IF A CST IS PRESENT

=0*0	[AR]_[AR]+WORK[CBR],	;YES, ADDRESS OF CST0 ENTRY

	CALL [RDPT]		;READ OLD VALUE

	[AR]_0,RETURN [2]	;NO CST, RETURN

	TL [AR],		;CHECK AGE FIELD

	#/770000

=

=0	[AR]_[AR].AND.WORK[CSTM],	;CLEAR AGE FIELD

	RETURN [2]		;AGE IS NOT ZERO

	PAGE FAIL TRAP		;AGE TOO SMALL



=0

WRCST:	START NO TEST WRITE,

	J/IBPX

	RETURN [4]

.ENDIF/INHCST

.ENDIF/NOCST

;STILL .IF/KLPAGE

;SUBROUTINE TO LOOK AT PAGE POINTER

;CALL WITH POINTER IN AR

;RETURNS 1 IF TYPE 1

;RETURNS 2 IF TYPE 2

;RETURNS 3 IF TYPE 3

;GOES TO PFT IF TYPE 0 OR 4 THRU 7

SETPTR: [ARX]_[AR].OR.#,	;AND C AND W BITS

	#/753777		; OF ALL POINTERS

	[FLG]_[FLG].AND.[ARX],	; ..

	HOLD RIGHT		;KEEP IN LH OF FLG

	READ [AR],		;TYPE 4,5,6 OR 7?

	SKIP DP0		; ..

=0	TL [AR],		;HERE WE TEST FOR TYPE

	#/300000,		; ZERO POINTER

	J/STPTR1		;CHECK AT STPTR1

	PAGE FAIL TRAP		;BAD TYPE

=0

STPTR1: TL [AR],		;NOT ZERO

	#/100000,		;SEPERATE TYPE 2

	J/STPTR2		; ..

	PAGE FAIL TRAP		;TYPE 0



=0

STPTR2: TL [AR],		;SEPERATE TYPE 1

	#/200000,		; AND 3

	J/STPTR3		; ..

	RETURN [2]		;TYPE 2



=0

STPTR3: RETURN [3]		;TYPE 3

	RETURN [1]		;TYPE 1

;STILL .IF/KLPAGE

;SUBROUTINE TO FETCH A PAGE POINTER OR CST ENTRY

;CALL WITH ADDRESS IN AR

;RETURN 4 WITH WORD IN AR

;

RDPT:	VMA_[AR],		;LOAD THE VMA

	START READ,		;START MEM CYCLE

	VMA PHYSICAL,		;ABSOLUTE ADDRESS

	SKIP IRPT		;CHECK FOR INTERRUPTS

=0	MEM READ,		;NO INTERRUPTS

	[AR]_MEM,		;PUT THE DATA INTO AR

	RETURN [4]		;AND RETURN

	PAGE FAIL TRAP		;INTERRUPT





;SUBROUTINE TO SEE IF WE SHOULD REMEMBER AN EXEC SECTION PTR

;CALL WITH SKIP ON ADR.EQ.0

;RETURNS 2 IF WE SHOULD STORE AND 7 IF WE SHOULD NOT

;

=0

SHDREM:	RETURN [7]		;INDIRECT PTR

	[AR]_.NOT.[FLG]		;FLIP BITS

	TL [AR], FLG.W/1, FLG.C/1 ;BOTH BITS SET

=0	RETURN [7]		;NO--DON'T STORE

	RETURN [2]		;STORE



.ENDIF/KLPAGE

.IF/KIPAGE

;HERE IN KI10 MODE

;BR CONTAINS PAGE # AND ARX CONTAINS PAGE #/2



KIFILL: READ [BRX],		;USER REF?

	SKIP DP0		; ..

=0	[BR]-#, 		;EXEC--LESS THAN 340?

	#/340,			; ..

	SKIP DP18, 4T,		; ..

	J/KIF10			;FOLLOW EXEC PATH

KIUPT:	[ARX]_[ARX]+[UBR],	;POINTER TO PAGE MAP ENTRY

	LOAD VMA,		;PUT ADDRESS IN VMA

	VMA PHYSICAL,		;ABSOLUTE ADDRESS

	START READ,		;FETCH UPT WORD

	J/KIF30			;JOIN COMMON CODE

=0

KIF10:	[BR]-#, 		;EXEC ADDRESS .GE. 340

	#/400,			; SEE IF .GT. 400

	SKIP DP18, 4T,		; ..

	J/KIEPT			;LOOK AT KIF20

	[ARX]_[ARX]+#, 3T,	;EXEC ADDRESS .LT. 340

	#/600,			;IN EBR+600

	J/KIEPT			;JOIN COMMON CODE



=0

KIEPT:	[ARX]_[ARX]+[EBR],	;ADD OFFSET TO

	LOAD VMA,		; EPT

	START READ,		;START FETCH

	VMA PHYSICAL,		;ABSOLUTE ADDRESS

	J/KIF30			;GO GET POINTER

	[ARX]_[ARX]+#,		;PER PROCESS PAGE

	#/220, 3T,		; IS IN UPT + 400

	J/KIUPT			;JOIN COMMON CODE

KIF30:	MEM READ,		;WAIT FOR DATA

	[ARX]_MEM		;PLACE IT IN ARX

	TR [BR],		;SEE IF EVEN OR ODD

	#/1			; ..

;STILL .IF/KIPAGE

=0

KIF40:	READ [ARX],		;ODD

	SKIP DP18,		;SEE IF VALID

	J/KIF50			;JOIN COMMON CODE

	[ARX]_[ARX] SWAP,	;EVEN--FLIP AROUND

	J/KIF40			; AND CONTINUE



.ENDIF/KIPAGE

=0

KIF50:	PAGE FAIL TRAP

;AT THIS POINT WE HAVE THE PAGE MAP ENTRY IN RH OF AR

	[FLG]_[FLG].AND.NOT.#,	;CLEAR W AND C

	FLG.W/1, FLG.C/1	; FLAGS

	TR [ARX], #/020000	;CACHE ENABLED?

=0	[FLG]_[FLG].OR.#,	;SET CACHE BITS

	FLG.C/1, HOLD RIGHT	; ..

	TR [ARX], #/040000	;DO NOT CACHE

				;SEE IF CACHE BIT SET

=0	[BRX]_[BRX].OR.#,	;COPY BITS TO BRX

	#/020000,

	HOLD RIGHT

	TR [ARX],		; ..

	#/100000

=0	[FLG]_[FLG].OR.#,	;SAVE W

	FLG.W/1,		; ..

	HOLD RIGHT,		; ..

	J/KIF90			;ALL DONE

	TL [BRX],		;W=0, WRITE REF?

	WRITE CYCLE/1

=0

KIF80:	[BRX]_[BRX].OR.#,	;WRITE FAILURE

	#/100000, HOLD RIGHT,	;INDICATE THAT ACCESS WAS ON

	J/KIF50			;GO PAGE FAIL

	J/PFDONE		;ALL DONE



KIF90:	[BRX]_[BRX].OR.#,	;PAGE IS WRITABLE

	#/40000,		;TURN ON IN BRX

	J/PFDONE		;ALL SET

;HERE ON HARD PAGE FAILURES

HARD:	WORK[SV.BR]_[BR]	;SAVE BR (CLEANUP MAY NEED IT)

=0	[BR]_VMA,		;BUILD PAGE FAIL WORD

	CALL [ABORT]		;CLEAR ERROR

	[BR]_[BR].AND.#,	;SAVE THE FLAGS

	#/401237,		; ..

	HOLD RIGHT		; ..

	[BRX]_[BRX].OR.[BR],	;COMPLETE PAGE FAIL WORD

	J/KIF50			;GO TRAP



PFPI1:	SKIP IRPT		;TIMER TRAP?

=00

	[AR]_WORK[TIME1],	;YES--GET LOW WORD

	SPEC/CLRCLK,		;CLEAR CLOCK FLAG

	CALL [TOCK]		;DO THE UPDATE

	J/PFT1			;EXTERNAL INTERRUPT

	ABORT MEM CYCLE		;CLEAR 1MS FLAGS

=

PFPI2:	[AR]_WORK[SV.VMA],	;RESTORE VMA

	J/PF125





ABORT:	ABORT MEM CYCLE, RETURN [1]

;HERE ON PAGE FAIL TRAP

=0

PFT:	HALT [IOPF]		;IO PAGE FAILURE

PFT1:	[AR]_WORK[SV.VMA],

	SKIP/TRAP CYCLE		;SEE IF TRAP CYCLE

=0	TL [AR], FETCH/1,	;IS THIS AN INSTRUCTION FETCH

	J/PFT1A			;GO LOOK BELOW

	[AR]_WORK[TRAPPC]	;RESTORE PC

	READ [AR], LOAD FLAGS, J/CLDISP

=0

PFT1A:	J/CLEANED		;YES--NO PC TO BACK UP

FIXPC:	[PC]_[PC]-1, HOLD LEFT	;DATA FAILURE--BACKUP PC

=0

CLDISP:	CLEANUP DISP		;GO CLEANUP AFTER PAGE FAIL

=0000

CLEANUP:

CLEANED:			;(0) NORMAL CASE

	END STATE, SKIP IRPT,	;NO MORE CLEANUP NEEDED

	J/PFT2			;HANDLE PAGE FAIL OR INTERRUPT

	[AR]_WORK[SV.ARX],	;(1) BLT

	J/BLT-CLEANUP

	[PC]_[PC]+1,		;(2) MAP

	J/MAPDON

	STATE_[EDIT-SRC],	;(3) SRC IN STRING MOVE

	J/STRPF

	STATE_[EDIT-DST],	;(4) DST IN STRING MOVE

	J/STRPF

	STATE_[SRC],		;(5) SRC+DST IN STRING MOVE

	J/BACKD

	STATE_[EDIT-DST],	;(6) FILL IN MOVSRJ

	J/STRPF4

	STATE_[EDIT-SRC],	;(7) DEC TO BIN

	J/PFDBIN

	STATE_[EDIT-SRC],	;(10) SRC+DST IN COMP

	J/CMSDST

	END STATE, J/BACKS	;(11) EDIT SRC FAIL

	END STATE, J/BACKD	;(12) EDIT DST FAIL

	STATE_[EDIT-SRC],	;(13) SRC+DST IN EDIT

	J/BACKD

=

=0

PFT2:	[AR]_[UBR]+#,		;PREPARE TO STORE PFW

	#/500, 3T,

	J/PFT10

PFT3:	TAKE INTERRUPT		;PROCESS INTERRUPT

PFT10:	VMA_[AR],		;WHERE TO STORE PFW

	VMA PHYSICAL WRITE

=0	MEM WRITE,		;STORE PFW

	MEM_[BRX],

	CALL [NEXTAR]		;ADVANCE POINTER TO

				;PREPARE TO STORE PC

.IF/KLPAGE

.IF/KIPAGE

	TL [EBR], #/400000	;KL PAGING?

=0

.ENDIF/KIPAGE

	[BR]_FLAGS,J/EAPF	;YES--DO EXTENDED THING

.ENDIF/KLPAGE



.IF/KIPAGE

	[BR]_PC WITH FLAGS	;GET OLD PC

	MEM WRITE,		;STORE OLD PC

	MEM_[BR],

	J/EAPF1

.ENDIF/KIPAGE



MAPDON:	END STATE,		;CLEAR MAP BIT

	SKIP IRPT		;ANY INTERRUPT?

=0	[AR]_[BRX],		;RETURN PAGE FAIL WORD

	EXIT

	[PC]_[PC]-1, J/PFT3	;INTERRUPTED OUT OF MAP

				; RETRY INSTRUCTION



.IF/KLPAGE

=0

EAPF:	MEM WRITE, MEM_[BR],	;STORE FLAGS

	CALL [NEXTAR]		;STORE PC WORD

	MEM WRITE, MEM_[PC]	; ..

.ENDIF/KLPAGE



EAPF1:	[AR]_[AR]+1,

	VMA PHYSICAL READ,

	J/GOEXEC



NEXTAR:	NEXT [AR] PHYSICAL WRITE, RETURN [1]