domain runs (the road to NLL:) (2026-07-20)¶

Full path: E:\Dev\Ronny\NDInsight\SINTRAN\ND500\CARVE-RUN-TO-WORK-POSTING-CHAIN-2026-07-20.md Track: SINTRAN carving (Phase 4 - the road to the NLL: prompt). Method: direct read of SINTRAN-L NPL (MP-P2-N500.NPL, RP-P2-N500.NPL) for LOGIC, cross-checked against L07 symbol tables for the field/message-code VALUES (SYMBOLS\L07\*.TXT), and against the D4 finding (ND500-D4-RUN-BLOCKER-FINDING-2026-07-19.md) + the context-block carve (CARVE-SWAPPER-CONTEXT-BLOCK-BUILDER-2026-07-20.md).

Grades: [V] byte/symbol-verified from the L07 tables or from the D4 live harness; [I] inferred from NPL logic (NPL is a DIFFERENT revision than the L07 bytes - logic only, never final byte authority); [OPEN] unresolved. Numbers OCTAL unless prefixed 0x. ASCII only; "section N" not the sign.

BOTTOM LINE (answers the three questions)¶

What calls 5ACTSWAPPER / posts real SWPINFO work? A PAGE FAULT taken by a RUNNING ND-500 process (the domain, or any placed process). The fault arrives as a level-12 STOP message; SINTRAN's driver decodes it (DECOMESS -> TRAPDECODER) and, for trap 46 = PAGE FAULT, calls 5ACTSWAPPER, which writes SWMSG.SWPINFO (HSWPI=104) to point at the faulting message. It is NOT an explicit activation issued by RUN, and RUN does NOT post swapper work directly. [V]
What must the EMULATOR do to trigger it? The placed domain must actually START executing (RUN issues a 3START = mailbox 23B), and then generate a real level-12 STOP message - either a PAGE FAULT (STOPR=TRAPCODE, TRAPN=46) which routes to the swapper, or a MONITOR CALL (STOPR=MOCALL) which routes to MCHANDLE. There is no path where posting SWPINFO by hand substitutes for the domain running and faulting. [V]
Cross-check with the RUN precondition (task #13): RUN of a properly-placed domain issues the domain 3START; execution then reaches 5ACTSWAPPER ONLY through a page fault, and reaches NLL: output through MCHANDLE (monitor calls). The current D4 stop is UPSTREAM of all of this: the SWAPPER'S OWN cold-start (process 0) has not completed/parked, so RUN still fails "NO WELL DEFINED PROGRAM" and never gets to 3START the domain. 5ACTSWAPPER is not even reached yet. [V]

THE CHAIN (per-hop, graded)¶

operator RUN
  -> [H0] RUNN precondition (well-defined program)         [V, task #13]
  -> [H1] RUNN issues domain 3START (mailbox 23B)           [I]
  -> [H2] domain EXECUTES on the ND-500 CPU                 [I]
        |-- (a) MON call -> STOPR=MOCALL  -> DECOMESS -> MCHANDLE -> output "NLL:"   [V]
        `-- (b) page fault -> STOPR=TRAPCODE, TRAPN=46 -> DECOMESS -> TRAPDECODER    [V]
  -> [H3] TRAPDECODER: trap 46 = PAGE FAULT, not swapper's own -> CALL 5ACTSWAPPER   [V]
  -> [H4] 5ACTSWAPPER: SWMSG.SWPINFO := faulting message; reactivate swapper         [V]
  -> [H5] swapper wakes with REAL work, pages the fault in (5SWRT/MON 131), restarts [V/I]
        domain -> domain continues -> NLL:

H0 - RUN precondition [V, prior carve task #13]¶

RUN/GO/CONTINUE all issue RUNN = MON 60 subfn 12B; its "well defined program" runnable state is set only on the all-success path of PLACE's START-STANDARD-DOMAIN @043011. Source: ND500-D4-RUN-BLOCKER-FINDING-2026-07-19.md section 8. Not re-derived here.

H1 - RUN starts the DOMAIN via mailbox `3START` [I]¶

The domain is activated by a mailbox message carrying MICFU = 3START. Symbol [V]: 3STAR=000023 (= mailbox 23B StartProcess, SYMBOLS\L07\*). The N5XXC driver dispatch has 3START in slot 23 (STAOPP, MP-P2-N500.NPL:398). The servicer's 23B StartProcess is REAL/wired to CpuND500 (D4 finding section 7). The exact RUNN -> 3START emission site is on the ND-100 monitor side (nd-500-mon J04) and is [I] here, not carved in this pass.

H2 - the domain executes and STOPS for service [V]¶

When the running ND-500 process needs the ND-100, the CPU stops and a level-12 message is delivered to SINTRAN's driver kernel (N500, NXTMSG ex-queue loop). The answer decoder is DECOMESS (MP-P2-N500.NPL:803-819, src 135161):

135167  *MICFU@3 LDATX                                      % MIC.FUNC
135170  IF A=3MONCO OR A=3TRACO OR A=3START OR A=3WMONCO THEN
135204     *AAX STOPR; LDATX
135210     IF A=MOCALL     THEN CALL MCHANDLE               % STOP-REASON = MONITOR CALL
135214     ELSE IF A=5FMOCALL THEN CALL MCHANDLE            %              = file-transfer moncall
135221     ELSE IF A=TRAPCODE THEN CALL TRAPDECODER         %              = TRAP  (-> page-fault path)
135226     ELSE CALL 5RRTWT

Symbol pins [V]: MOCAL=000001 (MOCALL), TRAPC=000002 (TRAPCODE), 3MONC=000024, 3STAR=000023. - (a) MON-call sub-path [V]: the LINKAGE-LOADER domain prints NLL: through terminal-output monitor calls; each stops the CPU with STOPR=MOCALL and is serviced by MCHANDEL (MP-P2-N500.NPL:1267, src 136764), which does the I/O and restarts the domain. This path never touches the swapper. - (b) trap sub-path [V]: a non-resident reference stops with STOPR=TRAPCODE -> TRAPDECODER.

(A second entry to the same code, DECOERRMESS 135240, routes an error-answer with TRAPN=46 and a legal micro-func straight to ITRAPDECODER - same page-fault handling.)

H3 - TRAPDECODER: page fault -> activate swapper [V]¶

TRAPDECODER (MP-P2-N500.NPL:859-895, src 135314):

135320  *AAX TRAPN-1; LDDTX                 % D = TRAPNO
135324  IF D>53 THEN ... UNKNOWN TRAP
135327  ELSE IF D = 46 THEN                 % PAGE FAULT
135336  ITRAPDECODER: IF X >< SWMSG THEN
135354     *5RECE@3 LDATX                   % RECEIVER
135357     IF A-5SWPROC=0 GO ITRPERR        % page fault IN the swapper -> background monitor
135361     MSWPFAULT SHZ 10 + D             % pack reason
135364     *AAX TRAPN; STATX
135367     CALL 5ACTSWAPPER                 % <=== ACTIVATE THE SWAPPER

Symbol pins [V]: TRAPN=000016 (trap-number field in the message), MSWPF=000012 (MSWPFAULT), 5SWPR=011254 (5SWPROC = swapper process descriptor / receiver id). The NPL comment names D = 46 as PAGE FAULT (octal-vs-decimal of the literal not resolved here; the comment is authoritative for meaning). [V for the branch, I for the literal base]

5ACTSWAPPER is also called from three other sites, all "a process needs the pager": SWMC (swapper monitor call, 141765), the LNEWSWAP chain that serves the next FIFO waiter (136037), and the resident-place path (134154). [V - grep of MP-P2-N500.NPL]

H4 - 5ACTSWAPPER posts the work into SWPINFO [V]¶

5ACTSWAPPER (MP-P2-N500.NPL:2851-2908, src 144762); entry X = message requiring service:

144766  X=:D=:MSGTOSW; A:=5MBBANK
144771  *NNC24,CNVWADR                       % multiport phys addr of the message
144774  AD=:CMSGTOSW
144775  SWPWAIT; CALL WN5STATUS              % mark faulting proc "waiting for swapper"
144777  X:=SWMSG; CALL RN5STATUS
145001  IF A=PSWWAIT THEN                    % swapper FREE?
145006     AD:=CMSGTOSW; *AAX HSWPI; STDTX   %   SWMSG.SWPINFO := &message   <=== REAL WORK POSTED
145011     SWACTIVE; *AAX SWPFU-HSWPI; STATX %   SWMSG.SWPFU := active
145054     X:=SWMSG; *AAX SWPST; STATX       %   SWMSG.SWPST := reason (page fault)
145071     3MONCO; *MICFU@3 STATX            %   MICFU := 3MONCO (restart swapper after moncall)
145073     CALL MCCO ; CALL XACTRDY          %   reactivate the ND-500 (the swapper)
145111  ELSE
145112     % swapper BUSY -> insert message into the Swap-wait FIFO (X5SWF), served later by LNEWSWAP

Symbol pins [V]: HSWPI=000104 (SWMSG.SWPINFO), SWPFU=000101, SWPST=000103, 3MONC=000024. This is the write that makes SWPINFO non-zero. It runs only because a running process faulted.

H5 - swapper services the fault, restarts the domain [V/I]¶

Parked process 0 (the swapper) wakes, reads SWMSG.SWPINFO to find its work, and pages the fault in. The disk transfer is done by the ND-100 RT-program 5SWRT (RP-P2-N500.NPL:16-58, src 126464): A:=SWMSG+"SWPINFO"=:D:=5MBBANK; AD=:DSWMSG (phys addr of SWPINFO), then ABSLI; *MON 131 (ABSTR disk read of the page). On completion MONICO/5RRTWT restarts the faulted domain, which resumes and runs on toward NLL:. [V for 5SWRT/MON 131; I for the full loop-back]

The cold-start init message is DISTINCT from fault work [V/I]¶

At swapper START, SWMESS/MSWSTART (MP-P2-N500.NPL:428-462, src 133635) also writes SWMSG.SWPINFO (133654), but to the swapper's own START message (MSWST=000007), not a page-fault work item. So SWPINFO is written on two different occasions: cold-start init (SWMESS) and per-fault work (5ACTSWAPPER). [V/I]

WHY the current D4 state has not reached H1 yet [V, from the finding]¶

Per ND500-D4-RUN-BLOCKER-FINDING-2026-07-19.md sections 12i-12l: on this ND-5800 image, PLACE-DOMAIN drives 500IN init (LOAD control store + LOAD swapper) and the SWAPPER (process 0) is 3START'd and executes. It runs clean on CpuND500 up to PC=0x0800913B, then dereferences a null taken from an EMPTY message (SWMSG buffer reads zero). That is the swapper's COLD-START path (SWMESS/MSWSTART), which should let the swapper initialize and PARK. Because it does not complete, PLACE never finishes, so: - RUN still prints NO WELL DEFINED PROGRAM (precondition H0 never satisfied), and - the DOMAIN LINKAGE-LOAD-H02 is never 3START'd, so no domain fault ever occurs, so - TRAPDECODER and 5ACTSWAPPER are not reached at all in the current state.

So the swapper-work-posting chain (H3-H5) is real and carved, but it sits BEHIND two gates that are not yet open: (1) swapper cold-start must park; (2) RUN must 3START the domain.

WHAT THE EMULATOR MUST DO TO REACH NLL:¶

In order, each a distinct requirement:

Make the swapper's cold-start COMPLETE and PARK (current blocker). The swapper reads its START message via SWMSG.SWPINFO and must reach its idle/park state, not null-deref. Either the START message (SWMESS/MSWSTART, SWPINFO=start msg) must be delivered non-empty, or the swapper's "no work -> park" branch must be taken. This is the top item (D4 finding 12l). [V - this is the wall]
Let RUN issue a real 3START (mailbox 23B) for the DOMAIN. Already wired: servicer 23B StartProcess is REAL (D4 finding section 7). Gated only by H0 (needs gate 1 first). [V]
Run the DOMAIN on CpuND500 and deliver its STOP messages faithfully:
- Monitor calls (how NLL: is printed): the domain stops with STOPR=MOCALL -> the emulator's 3022/mailbox must present that stop so DECOMESS -> MCHANDLE services the output. This is the MINIMAL path to NLL: and needs the swapper only if the domain page-faults. [V]
- Page faults (only if the placed domain is demand-paged): the CpuND500 page fault (LastPageFault) must be surfaced to the mailbox as a level-12 STOP with STOPR=TRAPCODE and TRAPN=46, NOT swallowed. Only that runs TRAPDECODER -> 5ACTSWAPPER and pages it in via 5SWRT (MON 131). [V]
Do NOT fake SWPINFO to shortcut this. RUN posts no swapper work; the swapper only ever gets work from a RUNNING process faulting (H2b -> H3 -> H4). A hand-written SWPINFO is not a substitute for the domain executing. [V]

Important honest nuance [OPEN]: whether LINKAGE-LOAD-H02 demand-faults at all is unresolved. If PLACE-DOMAIN placed its segments RESIDENT (the observed 14B RESIWR burst into ND-500 memory) and the CpuND500 MMU maps them, the domain can run to NLL: with zero swapper involvement - purely via the MON-call path (H2a / MCHANDLE), with the swapper idle. In that case the swapper-work chain (H3-H5) is NOT on the critical path to NLL:; the critical path is: swapper parks (gate 1) -> domain 3START (gate 2) -> domain MON-call output (MCHANDLE). The swapper-work chain becomes load-bearing only for a domain that actually demand-pages. Settling which case applies needs a live run once gate 1 is open.

Evidence index¶

Claim	Source	Grade
DECOMESS routes STOPR=TRAPCODE -> TRAPDECODER, MOCALL -> MCHANDLE	`MP-P2-N500.NPL:803-819` (135161)	[V]
TRAPDECODER: trap 46 = PAGE FAULT -> CALL 5ACTSWAPPER	`MP-P2-N500.NPL:859-895` (135314)	[V]
DECOERRMESS: TRAPN=46 + legal micfunc -> ITRAPDECODER	`MP-P2-N500.NPL:836-844` (135240)	[V]
5ACTSWAPPER writes SWMSG.SWPINFO := faulting msg, or FIFO-queues	`MP-P2-N500.NPL:2851-2908` (144762)	[V]
5ACTSWAPPER call sites (TRAPDECODER/SWMC/LNEWSWAP/resident-place)	grep `MP-P2-N500.NPL` (510/879/1052/2050)	[V]
SWMESS/MSWSTART sets SWPINFO to the START message (cold-start)	`MP-P2-N500.NPL:428-462` (133635)	[V/I]
Domain start = mailbox 3START (=23B); N5XXC slot 23 = STAOPP	`MP-P2-N500.NPL:398`; `3STAR=000023`	[V/I]
MCHANDEL services domain monitor calls (NLL: output path)	`MP-P2-N500.NPL:1267` (136764)	[V]
5SWRT pages the fault in via MON 131 ABSTR	`RP-P2-N500.NPL:16-58` (126464)	[V]
Field/code values HSWPI/TRAPN/SWPFU/SWPST/3MONCO/3START/MOCALL/TRAPCODE/5SWPROC/MSWPFAULT	`SYMBOLS\L07\*.TXT`	[V]
Current D4 stop is swapper cold-start (0x913B null-deref), not the domain	`ND500-D4-RUN-BLOCKER-FINDING-2026-07-19.md` 12i-12l	[V]
Whether LINKAGE-LOAD-H02 demand-faults or runs resident	(needs live run)	[OPEN]