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MON 43B (octal) - CloseFile (CLOSF)

CORRECTED 2026-07-15 (byte-verified). The worker + dispatch described below are on the DEBUNKED model and are WRONG. Byte truth from the carved L07 image: MCTAB[43B] = 005663B = CLOFI=103355B in segment 006-S3FS, reached by the real dispatch MON 43B -> ENT14(072167B) -> GOTAB[43B]=MFELL(072114B) -> CALLP(032201B) -> MCTAB[43B]=CLOFI. Any "GOTAB from commoncode" / "uncarved CALLPROC bridge" / "F16xx stub" / old worker name below is an artefact of the wrong table. Verified: dd if=044-S3IDPIT.bin bs=1 skip=1894 count=2 -> 86 ed. Cross-ref ../317B-ExecuteCommand/README.md and SINTRAN/CARVING-HANDOFF.md sec 3a.

Closes one or more open files. A file must be opened (with MON 50B OpenFile) before it is accessed and closed afterwards. The single argument is the open file number; -1 closes all files not permanently open, -2 closes all files including scratch and permanently open files. CloseFile also resets peripheral files.

Status: GOTAB dispatch head byte-proven (GOTAB[43B] = 121050B, the F1630 level-14 stub in 025-S3IRPIT); the CLOSF worker body is real SINTRAN L bytes and calls the FCLOS file-close primitive; the exact MON 43 -> worker link crosses an uncarved kernel bridge (see Honest caveats). All addresses/values are octal.

Dispatch path

flowchart LR
    A["User program<br/>MON 43B"] --> B["ENT14 level-14<br/>T = MON number"]
    B --> C["GOTAB[43B] = 121050B<br/>(byte-proven)"]
    C --> D["F1630 entry stub<br/>025-S3IRPIT :121050B"]
    D -.uncarved CALLPROC.-> E["CLOSF close worker<br/>006-S3FS :123741B"]
    E --> F["FCLOS file-close primitive<br/>006-S3FS :67612B"]
    class A blue
    class B,C,D teal
    class E,F green
    classDef blue fill:#E3F2FD,stroke:#0D47A1,color:#0D47A1
    classDef teal fill:#E0F7FA,stroke:#00838F,color:#00838F
    classDef green fill:#E8F5E9,stroke:#2E7D32,color:#2E7D32

The dashed hop (D -> E) is the resident CALLPROC/segment-switch - it is not present in any carved segment, so it is the one link that cannot be followed statically.

Code location (dispatch path)

Every row is a real region you can open. Byte offset = (addr - loadbase) in octal words x 2.

Role Segment (full disasm) Addr range (octal) Byte offset Symbol Verdict
GOTAB[43] dispatch word commoncode.asm - .hex 071276B (1 word) 58748 GOTAB+43 = 121050B VERIFIED
F1630 entry stub 025-S3IRPIT.asm - .hex 121050B-121074B (21w) 56400 F1630 VERIFIED
resident CALLPROC bridge - (uncarved) - - CALLPROC UNVERIFIED
CLOSF close worker body 006-S3FS.asm - .hex 123741B-123777B (37w) 63426 CLOSF real bytes; link MISATTRIBUTED
FCLOS file-close primitive 006-S3FS.asm - .hex 67612B (call target) 34580 FCLOS called by CLOSF (link cell 123775) - VERIFIED

Verify by hand: grep '^121050 ' ../../segments-ref/025-S3IRPIT/025-S3IRPIT.hex -> byte offset 56400; then dd if=../../../segments/025-S3IRPIT.bin bs=1 skip=56400 count=8 | od -An -tx1 -> cd ed f5 ff b3 02 a8 03 (= octal 146755 172777 131402 124003 = RADD AD1 CM1 CLD SA DA / AAA -1 / JAF 2 / JMP 3, the F1630 stub head).

The GOTAB slot itself: dd if=../../../resident/SINTRAN-DATA_commoncode.bin bs=1 skip=58748 count=2 | od -An -tx1 -> a2 28 (big-endian word = 121050B).

The CLOSF worker entry: dd if=../../../segments/006-S3FS.bin bs=1 skip=63426 count=8 | od -An -tx1 -> 22 16 cc 65 cc 59 f0 06 (= octal 021026 146145 146131 170006 = STD I 26 / RADD CLD SL DA / RADD CLD SB DD / SAB 6, the CLOSF entry).

Instruction walkthrough

Full listing: 43B-CloseFile.ASM. The functional body is the CLOSF worker (region B); the F1630 stub (region A) is the level-14 entry.

Region A - F1630 stub (121050-121074) is the compact level-14 entry pointed at by GOTAB[43]. It tests/normalises the argument (121050 RADD AD1 CM1 CLD SA DA, 121051 AAA -1, 121052 JAF 2) and loops over a small validation (121056-121074). Two direct branches leave the stub - 121054 JMP 106 -> 121162 and 121070 JMP 72 -> 121162 - into shared level-14 tail code that lives in sibling F16xx stubs (that address is inside F1633's range), and 121056 JPL I 123 -> 121201 calls a shared routine in F1634's range. These are the family's common level-14 handling, not the CLOSF file worker; the stub does not itself reach the CLOSF body (that transfer is the uncarved CALLPROC hop).

Region B - CLOSF worker (123741-123777) is the file-close body. All calls to shared workers are indirect (JPL I / JMP I) through a pointer table at the tail of the window (123767-123777); nd100-dis renders those pointer words as bogus instructions (ROP NOOP, STZ I ..., SUB I ...) - they are data (link cells), not code.

  • Entry prologue (123741-123745) - 123741 STD I 26 stashes the caller's double-word (the file-number argument); 123744 SAB 6 builds the small local frame B; 123745 JPL I 23 -> 003752 is the shared resident prologue worker (identical to the scratch and file read/write worker entries).
  • Argument parse (123746-123750) - 123747 JPL I 23 -> 044777 (CLPAR, parameter parse); a failure jumps to the store-status exit at 123763.
  • Close + finish (123751-123766) - 123752 JPL I 22 -> 010500 (resident worker) prepares, then 123754 JPL I 21 -> 067612 (FCLOS, the file-close primitive) performs the actual close. The two store-status points 123763/123765 STA ,B 2 write the result word into the caller's status slot B+2; every path funnels into the resident return 123762 JMP I -> 003776.

The JPL I 21 call to FCLOS (link cell 123775 = 067612) is the byte-level proof that CLOSF is the CloseFile worker - it drives the file system's close primitive, mirroring how OPENF drives FOPEN.

Parameter / register contract

Reg / field Dir Meaning Verdict
entry point (stub) in 121050B = F1630, the GOTAB[43] level-14 stub VERIFIED (bytes)
entry point (worker) in 123741B = CLOSF worker entry VERIFIED (bytes)
D (double) in caller parameter, saved first (STD I 26) VERIFIED (copy); layout inferred
local frame B internal SAB 6 = 6-word working frame VERIFIED (bytes)
T (manual) in file number to close (-1 = all non-permanent; -2 = all incl. scratch/permanent) inferred (manual MAC example)
A (manual) out error number on the error return inferred (manual)
B+2 out returned status word (STA ,B 2 at 123763/123765) VERIFIED (bytes)
error 3 (stub) out argument-error literal (SAA 3 at 121072) VERIFIED (bytes); mapping inferred

The user-visible T register convention lives in the caller-side MON 43 wrapper and the uncarved CALLPROC frame, so the precise user-register-to-field assignment is inferred from the manual, not byte-proven here.

Pseudo-code (for an emulator)

See 43B-CloseFile.pseudo.c - a pseudo-C model of the handler for emulator authors. Control flow + the call to the FCLOS primitive are byte-verified; the argument semantics and error-number meanings are inferred from the call structure and the manual.

Every instruction in the pseudo-code is translated against the canonical ND-100 instruction semantics reference (RADD/COPY register ops, addressing-mode effective addresses, and skip/branch senses).

Honest caveats

What is byte-proven: GOTAB[43B] = 121050B (level-14 dispatch); the F1630 stub at 121050B in 025-S3IRPIT is real code; the CLOSF worker body at 123741B in 006-S3FS is real code (entry bytes 021026 146145 146131 170006 match the disassembly); and it belongs to the file-close family - it calls FCLOS (067612B, link cell 123775), the file-close primitive.

What is NOT proven: the link from the F1630 stub (in 025-S3IRPIT) to the CLOSF worker (in 006-S3FS). The value 123741 occurs zero times as a target inside the F1630 stub; the stub's own direct branches stay in 025-S3IRPIT (to shared sibling-stub tail code at 121162/121201), and the stub->worker transfer is the resident CALLPROC/segment switch in an uncarved overlay. So the MON 43 -> CLOSF attribution rests on the CLOSF symbol name + its call to FCLOS + the matching close behaviour, not a followed pointer - hence MISATTRIBUTED in the strict sense. Confirming it needs a live trace: break at 121050B on a real MON 43, single-step the segment switch, and confirm P lands on CLOSF = 123741.

Region-A bound: the F1630 stub is bounded strictly to the next symbol F1631 = 121075B (21 words). Its two JMP -> 121162 branches and the JPL I 123 -> 121201 call land in neighbouring F16xx stubs' shared level-14 tail code; those are deliberately not included here (they are a different call's body) - the branches are noted, not swallowed.

Several link-cell contents (003752, 010500, 010506, 003776) match no FILSYS-SYMBOLS entry; their low addresses suggest resident-monitor / save-restore routines outside the file-system segment and are not resolved here.

Method: ../../../../../EXTRACTING-RESIDENT-CODE.md - dispatch reality: ../../TASK-05-mismatches.md - master map: ../../MON-CALL-INDEX.md.