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MON 327B (octal) - FileSystemFunction (GTYPR)

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[327B] = 006147B = MFFSC=111563B in segment 006-S3FS, reached by the real dispatch MON 327B -> ENT14(072167B) -> GOTAB[327B]=MFELL(072114B) -> CALLP(032201B) -> MCTAB[327B]=MFFSC. 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=2254 count=2 -> 93 73. Cross-ref ../317B-ExecuteCommand/README.md and SINTRAN/CARVING-HANDOFF.md sec 3a.

File-system information/maintenance "monster" call: a function code selects a sub-operation that classifies a file/object descriptor against type and size tables and returns packed status/flag/value words. The carved worker body is GTYPR ("Get TYP-RING") in segment 006-S3FS.

Status: dispatch word byte-proven (GOTAB[327B] = 112503B, non-zero, not a fall-through); the 112503B -> worker hop is UNVERIFIED (banked-overlay ambiguity); the carved GTYPR body is real SINTRAN L bytes but is MISATTRIBUTED - not statically reachable from 112503B. See Honest caveats. All addresses/values are octal.

Dispatch path

flowchart LR
    A["User program<br/>MON 327B"] --> B["ENT14 level-14<br/>T = MON number"]
    B --> C["GOTAB[327B] = 112503B<br/>(byte-proven, non-zero)"]
    C --> D["dispatch target<br/>025-S3IRPIT :112503B<br/>(overlay UNVERIFIED)"]
    D -.uncarved CALLPROC.-> E["GTYPR worker body<br/>006-S3FS :113312B"]
    E --> F["type/size classify<br/>-> B-frame result words"]
    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. 112503B sits in an alternately-banked overlay window (both 025-S3IRPIT and 006-S3FS cover it with different bytes), so which overlay is mapped at MON-327 time is a runtime paging decision, not in the static bytes.

Code location (dispatch path)

Byte offset = (addr − loadbase) in octal words × 2 (decimal). Verdicts follow the byte-level DISPATCH analysis, which wins over any older prose.

Role Segment (full disasm) Addr range (octal) Byte offset Symbol Verdict
GOTAB[327] dispatch word commoncode.asm · .hex 071562B (1 word) 59108 GOTAB+327 = 112503B VERIFIED
Level-14 dispatch target 025-S3IRPIT.asm · .hex 112503B–112532B 49798 DIA9 (SYMBOL-2-LIST) UNVERIFIED (banked overlay)
resident CALLPROC bridge — (uncarved) — — CALLPROC UNVERIFIED
GTYPR worker body 006-S3FS.asm · .hex 113312B–114035B 54676 GTYPR (FILSYS-SYMBOLS) real bytes; link MISATTRIBUTED

071562B = 071233B (GOTAB base) + 327B.

Verify by hand (dispatch word): grep '^59108' on the raw byte, or read it straight from commoncode: 

dd if=../../../resident/SINTRAN-DATA_commoncode.bin bs=1 skip=59108 count=2 2>/dev/null | od -An -tx1
# -> 95 43  (big-endian word 0x9543 = 112503 octal = GOTAB[327])
Verify by hand (dispatch target 112503B = DIA9): 
grep -n 'DIA9' ../../segments-ref/025-S3IRPIT/025-S3IRPIT.symbols.txt
dd if=../../../segments/025-S3IRPIT.bin bs=1 skip=49798 count=8 2>/dev/null | od -An -tx1
# -> 48 11 d1 01 d0 43 5a 0d  (big-endian words 044021 150401 150103 055015 = DIA9)
Verify by hand (GTYPR worker 113312B): 
grep -n 'GTYPR' ../../segments-ref/006-S3FS/006-S3FS.symbols.txt
dd if=../../../segments/006-S3FS.bin bs=1 skip=54676 count=8 2>/dev/null | od -An -tx1
# -> 22 7f cc 65 cc 59 f0 37  (big-endian word 021177 = STD I 177, the GTYPR entry)

Instruction walkthrough

Full listing: 327B-FileSystemFunction.ASM. The functional body is the GTYPR worker (region B); region A is the byte-verified dispatch target 112503B in 025-S3IRPIT (an overlay-ambiguous window - see caveats). Pointer WORDS embedded in region B (113511-113524, 113705-113716, 114020-114034) are data that the disassembler linearly decoded as pseudo-instructions, not executable code.

Entry prologue (113312-113316) - STD I 177 saves caller D through a pointer word; SAB 67 establishes the local B-frame; JPL I 174 (ptr @113512 = 003752B) calls a resident file-system worker.

Function-code range check (113317-113331) - LDT 172 loads a limit; A is compared (SKP IF DA GRE ST), adjusted (AAT 100), and normalised (SUB 165) into B+63; JPL I 164 (ptr @113515 = 010376B) calls a resident worker.

Descriptor scan + type/size classification (113347-113525) - reads a multi-word descriptor via X (LDA ,X 0/1/3/6/7/11/22/23/44/45), tests flags with BSKP ZRO/ONE n DA, and walks a stride-2 table (LDX ,B 60 / AAX 2 / MIN ,B 57 / JMP 113360, counter in B+57). It builds a value into B+61, a function selector (1/2/3) into B+62, and a result into B+63. Error/short paths jump indirect to the error-return entry 114016B.

Type-value membership test (113576-113640) - a straight-line SAT n / SKP IF DA UEQ ST chain over the whitelist {3,20,21,25,32,33,34,40,41} (octal) against B+61. A match sets SAX 1 and jumps to result assembly (113765); no match falls to the size ladder.

Size/threshold classification (113717-113764) - a descending ladder (LDT 100/76/74/72/70/66/64/62/60/56/54/52; SKP IF DA GRE ST) maps B+61 (a size/count) into a ring/category bucket - consistent with the GTYPR = Get TYP-RING name.

Result assembly and exit (113765-114017, 114035) - sets a status bit (LDA ,B 65 / BSET ONE 10 DA / STA ,B 65), then publishes B+64 -> B+3 (flags), B+65 -> B+0 (status), B+63 -> B+2 (value). The normal return executes MIN ,B 4 at 114013 (bumping the caller's skip/return-index field) and leaves via JMP I 20 (ptr @114035 = 003776B). The error return is entered at 114016 (STA ,B 2; JMP -3 -> 114014), joining the exit but SKIPPING the MIN ,B 4 - so an error does NOT bump the skip field.

Resident pointer targets (all octal, outside the carved window, unresolved to names): 003752, 010376, 020274, 055566, 056307, 071413, 003776.

Parameter / register contract

Item Dir Verdict Notes
A (function code) in VERIFIED (bytes) Range-checked at entry (LDT 172, AAT 100, SUB 165) and used as an index/selector.
X in VERIFIED (bytes) Points to a multi-word file/object descriptor; routine reads ,X 0/1/3/6/7/11/22/23/44/45.
B+0 out VERIFIED (bytes) Status word (B+65 copied here at 114010).
B+2 out VERIFIED (bytes) Value word (B+63 at 114012; error path stores A here at 114016).
B+3 out VERIFIED (bytes) Flags word (B+64 copied here at 114006).
B+4 out VERIFIED (bytes) Skip/return-index field bumped (MIN ,B 4) on the normal path only.
normal vs error return out VERIFIED (bytes) Normal = MIN ,B 4 executed; error = entered at 114016, MIN ,B 4 skipped.
T = per-function selector in inferred NPL claims T selects func 1/2/3/4; here the selector lands in A, not obviously T.
A = open-file/device no. in inferred NPL/README claim; A is used but its caller meaning is not provable from these bytes.
D = TYPRING bits out out inferred NPL claim; results here land in the B-frame slots, not visibly in D.

The caller-visible register convention lives in the caller-side MON 327 wrapper and the uncarved CALLPROC frame, so the precise T/A/X assignment is inferred, not byte-proven in this window.

Pseudo-code (for an emulator)

See 327B-FileSystemFunction.pseudo.c - a pseudo-C model of the GTYPR worker for emulator authors. Control flow, the type/size classification, and the normal-vs-error return split are byte-verified; the descriptor-field and caller-register semantics are inferred from the call structure. Every instruction is translated per the canonical ND-100 Instruction Semantics reference.

Honest caveats

What is byte-proven: GOTAB[327B] = 112503B (level-14 dispatch word, read straight from commoncode.bin, non-zero - so 327 is NOT a fall-through). The GTYPR worker bytes at 113312B..114035B are real SINTRAN L bytes and are control-flow closed: every direct branch lands inside the window, and the routine is a type/size classifier that reads an X-descriptor and returns packed status/flag/value words in a B-frame with a normal-vs-error return split.

What is NOT proven (single clear story): the link from the dispatch target 112503B to the GTYPR worker 113312B. - 112503B ≠ 113312B. The dispatch word points at 112503B, not at GTYPR. - 112503B lies in a banked-overlay window covered by BOTH 025-S3IRPIT (where the symbol table calls it DIA9, a device-driver-style name - almost certainly an overlay-mismatch name, since a file-system call would run under the file-system PIT, not the device PIT) and 006-S3FS (different bytes). Which overlay is mapped at MON-327 runtime is a paging-context decision, not in the static bytes - so the name DIA9 is not trustworthy and the hop is UNVERIFIED. - A scan of 006-S3FS for any pointer word equal to 113312B in 112000..113312 returns ZERO hits; the 025-S3IRPIT code at 112503B makes one direct in-segment jump (JMP -44 -> 112447) and never references 113312B. So GTYPR is NOT statically reachable from 112503B - hence MISATTRIBUTED. - The symbols FSMTY and MFELL used in earlier folklore do not exist in any L07 symbol table; do not treat them as L facts. (Note also a symbol-table conflict: FILSYS-SYMBOLS says GTYPR = 113312, while N500-SYMBOLS says GTYPR = 107550 - even the worker's own address is revision-dependent.)

Confirming the real path needs a live trace: break at the ENT14 dispatch for MON 327, confirm P lands at 112503B, read the PIT/paging registers to identify the mapped overlay, then single-step the first JMP I/JPL I that leaves the overlay and confirm whether control reaches GTYPR.

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