ER[MAP];
*I = 147
TARGET[ILC];
%IN THE MAP CURRENTLY 13-BIT PAGE NUMBERS ARE USED, CONSISTENT WITH THE
BBN PAGER. THIS CAN BE INCREASED TO 15 BITS IF DESIRED. MAP← AND MAP4←
CAUSE THE 22-BIT ENTRY(IES) SELECTED BY CUM*1000 + Y TO RECEIVE B[22,43].
THE ADDRESS LIMIT REGISTER (ALR) CONTAINS THE FIRST ILLEGAL PAGE NO. FOR
USER MODE MAP LOADING. THE THREE-BIT ALR IN 71 FROM WHICH THE PAGER
LOADS ITSELF IS CONVERTED TO THE MICROSTORE ALR AS FOLLOWS:
1 TO 7 BECOME (((1 TO 7) XOR 7) + 1) LCY 5; 0 BECOMES 1000.
THE TIMING FOR MAP LOADING WHEN NO TRAPS OCCUR IS AS FOLLOWS:
UBR 20 CYCLES 0 CYCLES PRIVATE
MBASE 19 CYCLES + 2R + 1W + 4 CYCLES + 1R SHARED
MBR 20 CYCLES 3 CYCLES + 1R INDIRECT
+ 2 CYCLES ON THIRD PAGE TABLE
I = 114 FOR MAP LOADING
S = ?
DEEPEST STACK DEPTH (INCLUDING CALL) =3
AT CALL: "LEFADR" (HOLDS TRAP STATUS) IS SETUP AS BELOW, E IS IN "REFADR",
Q SETUP AS BELOW, MDR HOLDS WRITE DATA, AND Y.CUM POINTS TO MAP ENTRY.
THE E IN LEFADR IS THE SAME AS IN REFADR EXCEPT ON FORCED REFERENCES TO USER
AC'S FROM MONITOR MODE (IN WHICH CASE E = ACBASE + E). THE L.H. OF LEFADR
CONTAINS APPROPRIATE INDIRECT, READ, WRITE, AND EXECUTE TRAP STATUS
BITS WITH THE MONITOR MODE BIT ALWAYS SET AND WITH "PGRPIC" SET IF PC IS NOT
TO BE DECREMENTED ON A TRAP. THE VALUE IN Q CHECKS P.T.E.'S FOR TRAPS.
IT CONTAINS USER, MONITOR, AND ACCESS TRAP BITS AND THE APPROPRIATE
READ, WRITE, AND EXECUTE PERMIT AND WRITE-COPY BITS.
AT RETURN: MAR, LEFADR, LPGRT, LPGRT2, LPGRT3, RPGRT, RPGRT2, RPGRT3,
THIRDPT AND MONALT ARE CLOBBERED, THE MAP HAS BEEN LOADED, REFADR IS IN P,
1 IS IN Q, MAPVA←REFADR, MDR PRESERVED. LOADMAP RETURNS ONLY IF IT
LOADS THE MAP. OTHERWISE, IT TRAPS AS DESCRIBED BELOW:
LEFADR (MODIFIED BY TRAP CAUSE AND PICYCLE) IS STORED INTO [MBR + TSTAT];
WDATA.WDATAL IS STORED INTO [MBR + TSTAT + 1];
UNMAPPED LOCATION [MLTRAP] IS EXECUTED IN MONITOR MODE.
* A PICYCLE MAP LOADING TRAP WILL ALSO SET BIT 40 000000 IN LEFADR.
* "CST", "SPT", "MBASE" DO NOT HAVE TO BEGIN AT SPECIAL BOUNDARIES
AS THEY DO FOR THE BBN PAGER BECAUSE ADDRESSES INSIDE THEM
ARE COMPUTED BY AN "ADD" RATHER THAN AN "OR".
*PLANS ARE AFOOT TO PUT IN BOUNDS CHECKS FOR SPT INDEX > BOUND AND
AGE NO. > BOUND
* "ACBASE" CONTAINS 775000 + PSWIT[22,26]*20
* ON INDIRECT MAP LOADING, A TRAP OCCURS IF THE INDIRECT PAGE TABLE CST
ENTRY AGE < 100B (BBN PAGER DOESN'T DO THIS).
* THE 3-BIT ALR LOADED FROM PSWIT MAY BE CHANGED INTO A 9-BIT QUANTITY
%
*PARAMETERS REFERRING TO BITS IN PAGE TABLE ENTRIES
*PTE[0,1] IS CODED AS FOLLOWS: 0=PRIVATE, 1=SHARED, 2=INDIRECT, 3=ILLEGAL
MP[RA,2]; *READ ACCESS PERMISSION
MP[WA,3]; *WRITE ACCESS PERMISSION
MP[XA,4]; *EXECUTE ACCESS PERMISSION
*MP[UT,10]; *USER TRAP BIT
MP[WCT,11];*WRITE COPY TRAP BIT
MP[MT,12]; *TRAP TO MONITOR BIT
MP[IMT,13];*IMMEDIATE TRAP BIT (WHEN MT=1, IMT=0 TRAPS AFTER LOADING
*A MAP REGISTER AND IMT=1 TRAPS IMMEDIATELY)
MP[ACC,14];*ACCESSED BIT (TRAP IF ACC=0)
PM[QBITS,1240 000000]; *UT, MT, ACC
MC[CBITS,RA,WA,XA,ACC]; *BITS WHICH ARE COMPLEMENTED IN P.T.E.'S BEFORE
*CHECKING FOR TRAPS
MC[MT&ACC,MT,ACC];
SM[UT,IP[1000 000000S]]; ***BECAUSE MICRO CAN'T MERGE IDENTICAL CONTS.
MC[IMT&ACC,IMT,ACC];
MC[MT&IMT&ACC,MT,IMT,ACC];
MC[RA&XA,RA,XA];
SM[WCT,IP[400 000000S]]; ***
SM[WA,IP[40000 000000S]]; ***
*PARAMETERS REFERRING TO CORE STATUS TABLE ENTRIES
SM[DIRTY,IP[400 000000S]];
SV[CSTBITS,700000 000000];
*PARAMETERS REFERRING TO THE TRAP STATUS WORD (LEFADR)
*MP[PGRPARITY,11]; *PARITY ERROR ON CST, PTE, OR SPT REFERENCE
*MP[PGRNXM,12]; *NON-EXISTENT MEMORY ERROR ON CST, PTE, OR SPT REF.
*MP[PGRKEY,13]; *KEY CYCLE (N.I.)
MP[PGRPIC,14]; *PI CYCLE IN PROGRESS
MP[PGRIND,15]; *INDIRECT ADDRESS SEQUENCE IN PROGRESS
MP[PGRRR,16]; *READ REQUEST
MP[PGRWR,17]; *WRITE REQUEST
MP[PGRXR,20]; *EXECUTE REQUEST
MP[PGRMM,21]; *MONITOR MODE
MC[PGRRR&PGRXR,PGRRR,PGRXR];
*TRAP CODES FOR LEFT NINE BITS OF LEFADR
SM[MALTRAP,IP[4000 000000S]]; *MONITOR AFTER-LOADING TRAP
*300000 000000 TRAP CODE ISN'T USED
*THE FOLLOWING CODES ALL HAVE BIT 1 SET
SM[SHRNIC,IP[40000 000000S]]; *SHARED N.I.C.
SM[PT2NIC,IP[20000 000000S]]; *PT2 N.I.C.
*BBN PAGER'S 210000 000000 TRAP (3RD P.T. PRIV N.I.C.) N.I. IT IS
*INCLUDED IN THE 2ND P.T. PRIV. N.I.C. TRAP
SM[INDSNIC,IP[4000 000000S]]; *INDIRECT-SHARED PAGE N.I.C.
SM[PT3NIC,IP[2000 000000S]]; *PT3 N.I.C.
SM[XSIND,IP[1000 000000S]]; *TOO MANY INDIRECT POINTERS
*THE FOLLOWING CODES ALSO SET BIT 1 IF TRAP IS IN SECOND OR THIRD PTE
SV[PNIC,500000 000000]; *PRIVATE N.I.C.
SM[WCTRAP,IP[440000 000000S]]; *WRITE COPY TRAP
SV[USRTRAP,420000 000000];
SV[ACCTRAP,410000 000000]; *ACC=0 OR MT=1 AND IMT=0
SV[ILLRX,404000 000000]; *ILLEGAL READ OR XCT
SV[ILLW,402000 000000]; *ILLEGAL WRITE
SV[ALRV,401000 000000]; *ADDRESS LIMIT REG. VIOLATION OR P.T.E.[0,1]=3
*LEFADR (ADDRESS IN RH) VALUE PUT IN Q REFERENCE PC CHANGE
MC[XLE,PGRMM,PGRXR]; MC[XMQ,QBITS,XA]; *XREF PC←PC-1
MC[XNLE,PGRMM,PGRXR,PGRPIC]; *XREF NO CHANGE
MC[RLE,PGRMM,PGRRR]; MC[RMQ,QBITS,RA]; *RREF PC←PC-1
MC[ILE,PGRMM,PGRRR,PGRIND]; *IREF PC←PC-1
MC[BRLE,PGRMM,PGRRR,PGRPIC]; *RREF NO CHANGE
MC[RMWLE,PGRMM,PGRRR,PGRWR]; MC[RMWMQ,QBITS,RA,WA,WCT]; *RMWREF PC←PC-1
MC[BRMWLE,PGRMM,PGRRR,PGRWR,PGRPIC]; *RMWREF NO CHANGE
MC[WLE,PGRMM,PGRWR,PGRPIC]; MC[WMQ,QBITS,WA,WCT]; *WREF NO CHANGE
MC[BLTWLE,PGRMM,PGRWR]; *WREF PC←PC-1
*MAP VARIABLES
SVN[UBR]; SVN[MBR]; SVN[WDATA]; SVN[WDATAL]; SVN[PURAGER];
SVN[ALR]; SVN[ACBASE]; SVN[PLO];
*STORAGE:
*REFADR, RPGRT, RPGRT2, RPGRT3
*LEFADR, LPGRT, LPGRT2, LPGRT3
*G, H, MONALT, PICYCLE, CUM, AND THIRDPT ARE USED IN F
MC[CUM&G,CUM,G];
MC[PFLAGS,G,MONALT,THIRDPT];
MC[MONALT&G,MONALT,G];
MC[THIRDPT&G,THIRDPT,G];
MC[MQBITS,RA,WA,XA,WCT,QBITS]; *UNION OF LEGAL BITS IN Q
*777700 000000 MASKS THE BITS WHICH ARE ALWAYS 0 IN LEFADR
LOADMAP: LPGRT←Q, P←MQBITS;
NOT P AND Q, P←7777 777777R, BAMASK[30], Q←LEFADR, WDATA←MDR;
NOT P AND Q, CALL[SCRASH,ALU#0], P←Y, SETSF[CUM&G];
RPGRT←P, Q←600S, CALL[SCRASH,ALU#0];
P-Q, WDATAL←MDRL, GOTO[LDUMAP,G=1];
GOTO[READMAP,ALU<0], LPGRT2←A0, Q←MBASE;
*HERE IF MONITOR MODE REFERENCE AND PAGE NO. > 577
Q←MBR;
READMAP: READ←P+Q, CLEARF[PFLAGS], CALL[CHKTRAPS];
%RETURN HERE IFF AN INDIRECT POINTER WAS ENCOUNTERED AND NO TRAP
HAS OCCURRED (HOWEVER, MONALT MAY BE SET IF A MONITOR-AFTER-LOADING
TRAP WAS REQUESTED). THE 2ND PAGE TABLE ENTRY IS IN MDR, 1B1 IS IN Q,
AND LEFADR IS IN P.%
LEFADR←P OR Q, CALL[CHKTRAPS], SETF[THIRDPT&G];
%HERE IFF AN INDIRECT-INDIRECT SEQUENCE IS IN PROGRESS--3RD P.T.E.
IS IN MDR. CHKTRAPS WILL NOT RETURN.
%
P←(MDR) U (177777 777777S), LEFADR←P OR Q;
P+1, CALL[CHKTRAPS,B>=0]; *SHARED OR PRIVATE
*PICK UP OTHER TRAPS IF ILLFORM
P←LEFADR, AMASK[33], Q←200000 000000S, CALL[CHKTRAPS,ALU=0];
P←(P OR Q) U (XSIND), GOTO[PTRAP];
LDUMAP: LPGRT2←A0, Q←ALR;
P-Q, P←LEFADR, Q←777777R;
GOTO[READMAP,ALU<0], LEFADR←P-Q-1, Q←UBR, P←RPGRT; *CLEAR PGRMM
P←LEFADR, Q←ALRV, GOTO[PTRAPU];
LEFSET: FRZBALUBC, LEFADR←P←P OR Q, RETURN;
%"CHKTRAPS" EXPECTS THE ACCUMULATED NOT ACCESS TO BE IN LPGRT2,
THIRDPT TO BE SET IF THE THIRD P.T.E. IS IN MDR. RPGRT IS USED
TO REMEMBER P.T.E.#CBITS.
%
CHKTRAPS: Q←CBITS, CALL[PMDR];
*IF THE PAGE IS DIRTY AND WRITES PERMITTED, WRITE ACCESS WILL NEVERTHELESS
*BE DISALLOWED IF THE WRITE-COPY TRAP IS SET. HENCE STUFF BELOW.
RPGRT←P←P#Q, Q←WCT;
P AND Q, Q←LPGRT2;
GOTO[.+2,ALU=0], Q←(Q) U (WA), P, PQ LCY [1];
LPGRT2←Q, FRZBALUBC;
P, GOTO[INDILL,ALU<0], P←RPGRT, Q←LPGRT, MDR←SPT;
P AND Q, PQ RCY [11], SAMASK[15], Q←MDR, GOTO[SHARED,ALU<0];
Q←17 000000S, P←RPGRT, FRZBALUBC;
P AND Q, PQ RCY [0], SAMASK[13], DGOTO[.+3,ALU=0];
CALL[LEFSET,ALU#0], RPGRT2←P, P←LEFADR, Q←PNIC, FRZBALUBC;
CALL[SETTRAPS], P←RPGRT, Q←MT&ACC, A0;
*RETURN HERE IFF ONLY TRAP IS MONITOR-AFTER-LOADING WITH ALU=0.
*ENTER HERE FROM ABOVE WITH PRIVATE NOT-IN-CORE TEST PENDING.
Q←CST, P←RPGRT2, GOTO[LTRAP,ALU#0];
%CSTCHK EXPECTS P.T.E.#CBITS IN RPGRT (GARBAGE IN OTHER BITS), CST IN P
AND CORE PAGE NO. IN Q (CAN BE REVERSED), CORE PAGE NO. IN RPGRT2, AND
ACCUMULATED NOT-ACCESS IN LPGRT2.
%
CSTCHK: RMW←P+Q, INHINT, P←RPGRT, Q←LPGRT2;
*POSITION NOT-ACCESS IN LPGRT2 FROM B[2,4] TO B[18,20]
NOT(NOT P AND NOT Q)Q RCY [20], Q←700000S;
P←P AND Q, Q←RPGRT2, SETSF[MONALT&G];
RPGRT2←P OR Q, P←WA, Q←LPGRT;
P AND Q, Q←CSTBITS, CALL[PMDR];
P AND Q, Q←DIRTY, GOTO[SETDIRTY,ALU#0];
GOTO[CSTTRAP, ALU=0], WRESTART, MDRL←WDATAL;
SETD1: P AND Q, Q←MALTRAP, PQ RCY [0], BAMASK[33], INHINT;
MDR←(P) U (PURAGER), P←Q, GOTO[.+2,ALU#0], POP, Q←RPGRT2;
Q←(Q) U (200000S); *TURN-OFF WRITE PERMISSION
MAP←Q, P←LEFADR, SAMASK[33], Q←P, GOTO[PTRAPU,G=1];
YKPTR←NULL, P←REFADR, CALL[EVINC]; *INC. MAP LOADING COUNTER
MDR←WDATA;
JUMPA: MAPVA←P, Q←1R, BAMASK[22], RETURN; *RETURN TO CALLER OF LOADMAP
*P HAS CST ENTRY MERGED WITH PUR. ALU=0 IFF CSTTRAP.
SETDIRTY: P←P OR Q, GOTO[SETD1,ALU#0], WRESTART, MDRL←WDATAL;
%CSTENTRY[3,4] DETERMINE THE TRAP CODE WHEN CSTENTRY[0,2]=0 AS FOLLOWS:
0 100000 000000
1 40000 000000
2 20000 000000
3 10000 000000
%
CSTTRAP: Q←40000 000000S;
P AND Q, Q←20000 000000S;
P AND Q, P←LEFADR, SAMASK[33], GOTO[.+3, ALU=0];
P←(Q←P) U (10000 000000S), GOTO[PTRAP,ALU#0];
P←(Q) U (20000 000000S), GOTO[PTRAP];
GOTO[PTRAP,ALU#0], P←(Q←P) U (40000 000000S);
P←(Q) U (100000 000000S), GOTO[PTRAP];
%ON INDIRECT REFERENCES THE ACCESS FINALLY ALLOWED TO THE PAGE IS
THE LOGICAL AND OF THE ACCESS PERMITTED BY SUCCESSIVE P.T.E.'S.
LPGRT2 HOLDS ACCUMULATED NOT ACCESS. RPGRT WILL HOLD
P.T.E.#CBITS.%
INDILL: P AND Q, Q←LPGRT2, GOTO[.+3,ALU>=0];
*HERE FOR ILL. FORMAT PAGES WITH TRAP TESTS PENDING
P←LEFADR, Q←ALRV, FRZBALUBC, DGOTO[LTRAP];
LEFADR←P OR Q, CALL[STRAPS,ALU#0];
LPGRT2←P OR Q, GOTO[.+3,ALU=0], Q←777S;
*P.T.E.#CBITS IN P, RPGRT AND MDR
Q←MT&ACC, CALL[SETTRAPS];
*RETURN HERE IFF ONLY TRAP IS MONALT
P←RPGRT, Q←777S;
*SAVE IND. PAGE NO. IN RPGRT
RPGRT←P AND Q, PQ RCY [11], Q←SPT, BAMASK[15];
** EVENTUALLY PUT BOUNDS CHECK FOR SPT READS HERE
READ←P+Q;
Q←17 000000S, CALL[PMDR];
P AND Q, PQ RCY [0], BAMASK[13], SETSF[THIRDPT&G];
GOTO[INDNIC,ALU#0], Q←P, P←CST;
** EVENTUALLY PUT BOUNDS CHECK HERE
*READ CST, GET CORE PAGE LCY 11
RMW←P+Q, 0Q RCY [33], Q←RPGRT, INHINT;
*PUT ADDRESS OF NEXT P.T.E. IN RPGRT
RPGRT←P+Q, Q←CSTBITS, CALL[PMDR];
P AND Q, PQ RCY [0], SAMASK[33], WRESTART, Q←MDR;
GOTO[CSTTRAP, ALU=0], INHINT, Q←P, P←Q;
MDR←(Q) U (PURAGER), Q←RPGRT, P←-1L, A0, BAMASK[42];
READ←Q, P←LEFADR, Q←P+1, FRZBALUBC, GOTO[RETN];
INDNIC: P←LEFADR, AMASK[33], Q←200000 000000S;
P←(Q←P OR Q) U (PT2NIC), GOTO[PTRAP,G=0];
P←(Q) U (PT3NIC), GOTO[PTRAP];
*HERE WITH PTE#CBITS IN RPGRT AND P, WITH TRAP TESTS IN LPGRT AND Q
SHARED: CALL[STRAPS,ALU#0], READ←P+Q; *RETURN IFF ONLY TRAP IS MONALT
Q←17 000000S, CALL[PMDR];
P AND Q, BAMASK[13];
GOTO[CSTCHK,ALU=0], RPGRT2←P, Q←CST;
*SHARED NOT-IN-CORE HERE
P←(LEFADR) LSH [1], Q←200000 000000S;
P, BAMASK[33], P←LEFADR;
GOTO[PTRAP,ALU<0], P←(Q←P OR Q) U (INDSNIC);
P←(Q) U (SHRNIC), GOTO[PTRAP];
*MUST TOUCH MDR TO TERMINATE READ AT "SHARED" FOR MAXC2
QPRPG: Q←P AND Q, P←RPGRT, FRZBALUBC, MDR, RETURN;
LEFPQF: LEFADR←P OR Q, P←RPGRT, Q←UT, FRZBALUBC, RETURN;
%"SETTRAPS" IS CALLED WITH P.T.E.#CBITS IN RPGRT AND P, MT&ACC IN Q,
LEFADR PROPERLY SET, CORE PAGE NO. IN RPGRT2 (PRIV. PAGES), ACCUMULATED NOT
ACCESS IN LPGRT2, APPROPRIATE R, W, E, WCT, MT, AND ACC IN LPGRT, AND ONE OR
MORE TRAPS DETECTED. MDR CONTAINS READ[SPT+SPTNO] ON SHARED OR INDIRECT ENTRIES.
RETURN WITH ALU=0 IFF ONLY TRAP IS MONALT, ELSE TRAP.
%
STRAPS: P←RPGRT, Q←MT&ACC;
SETTRAPS: P AND Q, Q←UT, GOTO[SETT5];
SETT4: P←LEFADR, Q←ACCTRAP, A0, CALL[LEFPQF];
SETT5: GOTO[SETT0,ALU=0], P AND Q, Q←RA&XA;
*HERE IF MONITOR TRAP OR IF ACCESS BIT NOT SET
Q←IMT&ACC, P←RPGRT;
P AND Q, Q←MT&IMT&ACC;
GOTO[SETT4,ALU#0], RPGRT←Q←P AND NOT Q, P←LPGRT;
*REMAINING TRAPS ARE IN Q, TRAP TESTS IN P
P AND Q, P←RPGRT, Q←UT, DGOTO[SETT5];
*MUST TOUCH MDR TO TERMINATE READ AT "SHARED" FOR MAXC2
MDR, RETURN[ALU=0], SETFC[MONALT&G,ALU=0], A0;
*HERE WITH USER TRAP TEST PENDING
SETT0: Q←P AND Q, P←LPGRT, FRZBALUBC;
P←LEFADR, Q←USRTRAP, P AND Q, CALL[LEFPQF,ALU#0];
P←LPGRT, Q←WA, FRZBALUBC, CALL[QPRPG];
*HERE WITH READ OR XCT VIOLATION TEST PENDING
P←LEFADR, P AND Q, Q←ILLRX, CALL[LEFPQF,ALU#0];
*HERE WITH WRITE VIOLATION TEST PENDING
P←LPGRT, Q←WCT, FRZBALUBC, CALL[QPRPG];
P AND Q, P←LEFADR, Q←WCTRAP, GOTO[.+2,ALU=0];
P←(P) U (ILLW), FRZBALUBC, GOTO[PTRAP,ALU=0];
GOTO[PTRAP,ALU=0];
*FALL THROUGH TO "PTRAPU"
%ALL TRAPS WIND UP AT "PTRAP" WITH TRAP STATUS IN P. TRAP STATUS IS
STORED IN (MBR U TSTAT), WDATA.WDATAL IN (MBR U TSTAT) + 1.
PC IS DECREMENTED IFF PGRPIC=0 IN LEFADR. PC[0,21] ARE ZEROED UNLESS
MD2=1 (=BYTE LISP), IN WHICH CASE ONLY PC[0,17] ARE ZEROED.
THE MACHINE CRASHES IF A PICYCLE IS IN PROGRESS AT THE TIME OF A
PAGER TRAP.
%
PTRAPU: P←P OR Q, GOTO[.+2];
LTRAP: P←LEFADR;
PTRAP: RPGRT←P, P←-1L, BAMASK[27], MDR←MBR;
*USE DGOTO'S BELOW FOR THEIR INHINT EFFECT
Q←P+1, P←WRITE←(MDR) U (TSTAT), DGOTO[.+2]; *Q←PGRPIC=40 000000
LPGRT2←P+1, P←RPGRT, SETSF[PICYCLE&K], DGOTO[.+2];
*STORE THE TRAP STATUS AFTER CLEARING THE "PGRPIC" BIT IN THE VALUE
*J REMEMBERS UM DURING THE TRAP CYCLE.
MDR←P AND NOT Q, SETSF[UM&J], CALL[SCRASH,K=1];
P←PC, P AND Q; *TEST PGRPIC BIT--DON'T DECREMENT PC IF 1
MDR←WDATA, AMASK[24], Q←LPGRT2, GOTO[.+2,ALU#0];
P←P-1; *CANNOT BE BYTE LISP
WRITE←Q, Q←777777R, SETSF[MD2&G], INHINT;
*CLEAR L.H. IF NOT IN BYTE LISP MODE
MDRL←WDATAL, Q←P AND NOT Q, CALL[PMQ,G=0];
OLDPC←Q←P, CLEARF[TFLAGSPI];
PC←Q;
READ←MLTRAP, Q←A0, GOTO[XCTA];
%JMC'S FOR MANIPULATING THE PAGER ARE AS FOLLOWS:
MAPRES TURNS OFF MAPPING, LEAVES PLO=0, ALR=1000
SETPLO SETS THE LOWER BOUND TO THE SWAPPABLE MONITOR
SPUR1 SETS AGE AND PROCESS USE REGISTERS
VPGCLR CLEARS VIRTUAL PAGE FROM MAP
APGCLR CLEARS ALL INSTANCES OF ABSOLUTE PAGE FROM THE MAP (=MAPCLR)
ASWIT RELOAD BASE REGISTERS FROM [PSWITCH] AND [PSWITCH+1]
MAPCLR CLEAR MAP ABOVE PLO
USWIT SWITCH TO NEW PROCESS CLEARING MONITOR PAGES 600 TO 777
AND USER PAGES 0 TO ALR-1 AND RELOADING BASE REGISTERS
FROM [PSWITCH] AND [PSWITCH+1]
I = 34
%
MAPRES:
*~ MAXC2 ONLY
P; *CAN'T READ/WRITE MAP AFTER CUM CHANGE
*~
MAP←Y, INCY, GOTO[.,Y>=0], Q←P+1;
PLO←MAP←Y, INCY, GOTO[.,Y<0]; *PLO←0
ALR←Q, Q←RTEMP, RETURN[G=1]; *RETURN "RTEMP" IN Q FOR CONSOLE RESET
SETF[CUM&G], GOTO[MAPRES], Y←NULL, P←777L;
*CALLED AFTER P←Y←NULL, Q←P
SETPLO: PLO←Q;
*"CLRMM1" ENTERED WITH SMALLEST MONITOR PAGE TO CLEAR IN P AND Y
CLRMM1: Q←200S, PQ RCY [2], BAMASK[12];
Q←P-Q, P←(-1L) LSH [1], CLEARF[CUM&G];
CLRUM1: X←P-Q; *MAP4← COUNT - 2 IN X
Q←700000S;
MAP4←Q, GOTO[.,X>=0], DECX;
RETN: RETURN, FRZBALUBC;
*ABSOLUTE PAGE NO. IN P--CURRENTLY CLEAR MAP FROM PLO TO ALR-1
MAPCLR: P←Y←PLO, CALL[CLRMM1];
Q←ALR, P←1R;
QQ RCY [2], Y←NULL, Q←2P, SETF[CUM&G], GOTO[CLRUM1];
%ROUTINE TO SET ACCESS TO 0 FOR ALL MAP ENTRIES BETWEEN PLO AND 1000 + UBR
FOR WHICH MAP[25,43] = E[31,43]
JMC DISPATCH INSTRUCTION = CLEARF[CUM&G], Y←A1, GOTO[APGCLR]
I = 9, TIMING = 13 + (1024-PLO) + 4/MAP CLEAR
*INSURE MATCH ON MAP ENTRY 777
APGCLR: Q←(P) U (700000S), CALL[APGC3];
Y←PLO;
APGC0: DGOTO[.+1];
P#Q, P←(MAP) U (700000S), INCY, GOTO[.,ALU#0];
DECY;
DECY, DGOTO[APGC0,Y<0];
*JUMP UNLESS LAST EXEC OR LAST USER MAP ENTRY (CLEAR IT, TOO)
MAP←Q, INCY, GOTO[APGC0,Y>=0];
*REPEAT FOR USER MAP
APGC2: SETF[CUM&G], Y←A1, RETURN[G=1];
*CLEAR MAP ENTRY AND RESUME LOOPING
MAP←Q, INCY, GOTO[APGC0];
%
*VIRTUAL PAGE NO. IN P[33,43] AND Y, USERMODE IN P[32]
VPGCLR: P AND Q, Q←700000S;
SETFC[CUM&G,ALU#0], Y←P, CALL[RETN,ALU#0]; *NEED NOOP AFTER SETF[CUM] ON MAXC2
APGC3: MAP←Q, RETURN;
USWIT: READ←PSWITCH, CALL[MAPCLR];
ASWIT: P←Q←MDR, DGOTO[340];
%NOW HAVE BASE REGISTER WORD IN P AND IN Q. BITS ARE USED AS FOLLOWS:
MBR IN P[31,43]
UBR IN P[7,21]
ACBASE IN P[22,26] BECOMES 775000 + 20*P[22,26]
ALR IN P[4,6]
%
PQ RCY [30], Q←NPC, RTEMP←P, GOTO[.+1];
P←P AND Q, MDR←1000S;
P←P#Q, Q←40S, GOTO[.+2,ALU=0];
MDR←P+Q;
ALR←MDR, P←RTEMP;
PQ RCY [11], Q←3 777000S;
Q←P AND Q, PQ RCY [0], BAMASK[11];
UBR←Q, Q←P, P←777L, BAMASK[4];
MDR←(NOT P AND Q) U (775000S), Q←RTEMP;
ACBASE←MDR, 0Q RCY [33], BAMASK[24], Q←777L;
Q←P AND NOT Q, P←PSWITCH;
MBR←Q;
*P←PSWITCH BEFORE CALL
SPUR1: READ←P+1, P←-1L, SAMASK[32], CALL[RETN]; *KNOW DIRTY=400 000000
P←MDR, Q←P+1, CALL[CLRPQ];
PURAGER←Q, RETURN;
%THE PAGER SHOULD BE CONTROLLED BY USING THE JMC'S PROVIDED FOR THAT
PURPOSE. HOWEVER, CURRENTLY THE CONO PGR FUNCTIONS FOR THE BBN
PAGER ARE EMULATED AS CLOSELY AS POSSIBLE.
CONO PGR IS EMULATED BY DISPATCHING TO ONE OF 8 ROUTINES SELECTED
BY E[33,35] AND DESCRIBED BELOW:
0 USWIT: CLEAR MONITOR MAP FROM PLO TO 777 AND USER MAP FROM
0 TO ALR-1 AND RELOAD BASE REGISTERS FROM [PSWITCH] AND [PSWITCH+1]
1 REMOVE ALL ACCESS PERMISSION FOR MONITOR PAGES PLO TO 777.
2 GOTO ILLIO (TRAP AT LOCATION 60)
3 REMOVE ALL ACCESS PERMISSION FOR USER PAGES 0 TO ALR-1
4 MAPRESET: TURN OFF MAPPING BY LOADING EVERY MAP ENTRY WITH A
POINTER TO THE CORRESPONDING ABSOLUTE PAGE NUMBER AND WITH ALL
ACCESS PERMITTED. SET PLO TO 0 AND ALR TO 1000.
5 MAPRESET
6 SET PLO TO 100 AND CLEAR MONITOR MAP ABOVE 100
7 SET PLO TO 0 AND CLEAR MONITOR MAP
I = 11, S = 7
PGRCO: PQ RCY [0], AMASK[3], Q←NPC, POP;
B←P+Q+1, NPC←B, GOTO[NOOPR]; *DISPATCH TO ONE OF 8 INST. BELOW
GOTO[USWIT], P←Y←PLO, POP;
GOTO[CLRMM1], P←Y←PLO, POP;
GOTO[ILLIO], POP;
GOTO[CLRUMAP], POP;
GOTO[MAPRESET], POP;
GOTO[MAPRESET], POP;
GOTO[.+2], P←Y←100S;
GOTO[CLRMM1], P←PLO←Y←NULL, POP;
PLO←Y, POP, GOTO[CLRMM1];
%