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MON 57B (octal) - GetUserParam (PAGEI)

Gets the 5 user parameters of a background program (why the last program terminated). SetUserParam (MON 56B) sets them. Background programs only.

Status: GOTAB dispatch head byte-proven (GOTAB[57B] = 121246B), pointing at the shared entry-stub block F1636 in 025-S3IRPIT; the MPAGE worker body is real SINTRAN L bytes in the second-level monitor segment 025-S3IRPIT (a SYMBOL-2-LIST symbol). MPAGE=102365B (this call) is the GET entry of a shared set/get body whose SET entry is MPASE=102363B (MON 56B); the SSK skip flag selects which. The stub block does not itself reach MPAGE; the exact MON 57 -> worker link crosses an uncarved kernel bridge (see Honest caveats). All addresses/values are octal.

Dispatch path

flowchart LR
    A["User program<br/>MON 57B"] --> B["ENT14 level-14<br/>T = MON number"]
    B --> C["GOTAB[57B] = 121246B<br/>(byte-proven)"]
    C --> D["F1636 entry stub<br/>025-S3IRPIT :121246B"]
    D -.uncarved CALLPROC.-> E["MPAGE get-param worker<br/>025-S3IRPIT :102365B (SSK=1)"]
    E --> F["get array; MST PIE;<br/>MOVUS 5 words system->user"]
    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. The stub F1636 sits in a shared stub block whose own branches leave its window; it is not a self-contained named handler and the worker address 102365 does not occur inside the stub.

Code location (dispatch path)

Every row is a real region you can open. Byte offset = (addr - loadbase) in octal words x 2; for 025-S3IRPIT (load base 32000B) it is (addr - 32000B) x 2.

Role Segment (full disasm) Addr range (octal) Byte offset Symbol Verdict
GOTAB[57] dispatch word commoncode.asm - .hex 071312B (1 word) 58772 GOTAB+57 = 121246B VERIFIED
F1636 entry stub 025-S3IRPIT.asm - .hex 121246B-121270B (shared block) 56652 F1636 VERIFIED (GOTAB target); shared stub block
resident CALLPROC bridge - (uncarved) - - CALLPROC UNVERIFIED
MPASE/MPAGE worker body 025-S3IRPIT.asm - .hex 102363B-102406B (code) + 102407B-102412B (link cells) 41450 MPAGE=102365B (SSK=1) / MPASE=102363B (SSK=0) real bytes = CODE; body link MISATTRIBUTED

The worker window is bounded strictly by the next symbol RERRP=102413B (a different handler). Words 102363B-102406B are code and 102407B-102412B are a pointer table (link cells) - one of them, 102410B, is the USPAR=145445B constant - they are data.

Verify by hand: the GOTAB word: grep '^71312 ' ../../segments-ref/SINTRAN-DATA_commoncode/SINTRAN-DATA_commoncode.hex -> 71312 121246 242 246 58772; then dd if=../../../resident/SINTRAN-DATA_commoncode.bin bs=1 skip=58772 count=2 2>/dev/null | od -An -tx1 -> a2 a6 (word = 121246B). The stub head: dd if=../../../segments/025-S3IRPIT.bin bs=1 skip=56652 count=2 2>/dev/null | od -An -tx1 -> f7 01 (= octal 173401, AAX 1, matching the disassembly). The MPAGE worker entry: grep '^102365 ' ../../segments-ref/025-S3IRPIT/025-S3IRPIT.hex -> byte offset 41450; then dd if=../../../segments/025-S3IRPIT.bin bs=1 skip=41450 count=2 2>/dev/null | od -An -tx1 -> f8 90 (= octal 174220, BSET ONE SSK, the MPAGE get entry). prove-mon.py 57 reads the same GOTAB value.

Instruction walkthrough

Full listing: 57B-GetUserParam.ASM. Two regions.

Region A - F1636 stub (121246-121270) is the GOTAB target in 025-S3IRPIT. It sits inside a shared stub block; its head (AAX 1 / SWAP SD DX / LDT I ,X 51 / SKP IF DA EQL ST) branches out of its own window (JMP 44 -> 121316, JMP -15 -> 121237), so it is not a self-contained per-call handler; the real transfer to the worker is the resident CALLPROC, which a static decode cannot follow.

Region B - MPASE/MPAGE worker (102363-102412) is the shared body. 102363 BSET ZRO SSK is the SET entry (MPASE, MON 56B); 102365 BSET ONE SSK is the GET entry (MPAGE, this call). Both join at 102366 JPL I 21 -> [102407] (get the array address); 102367 SAA 4 / 102370 MST PIE enter the monitor level; 102371 BSKP ONE SSK forks - the GET side (this call) puts USPAR in D and the user array in T. 102402 SAX 5 / 102404 JPL I 5 -> [102411] runs MOVUS to copy the 5 words; 102405 STZ ,B 12 clears the status and 102406 JMP I 4 -> [102412] returns.

Parameter / register contract

Manual-side names/types are from 57B_GetUserParam.yaml.

Reg / field Dir Meaning Verdict
Buff (5 words) out [0] dir/user index, [1] terminal LDN, [2] error number (-1 if ESCAPE), [3..4] user-defined inferred (manual)
entry point in 102365B = get (this call); 102363B = set (shared body, SSK split) VERIFIED (bytes)
SSK internal set (0) / get (1) direction selector (BSKP ONE SSK at 102371) VERIFIED (bytes)
B+20 (D0) internal user-array pointer used as one side of the MOVUS copy VERIFIED (bytes); meaning inferred
USPAR=145445B internal system-side parameter array (the other MOVUS side) VERIFIED (bytes)
A out status word cleared to 0 on success (102405 STZ ,B 12) VERIFIED (bytes); meaning inferred

Pseudo-code (for an emulator)

See 57B-GetUserParam.pseudo.c - a pseudo-C model for emulator authors. The control flow (the SSK set/get split taking the get branch, the monitor entry, the 5-word MOVUS copy and the zeroed return status) is byte-verified; the buffer layout is inferred from the manual and the monitor-call source shape.

Every instruction in the pseudo-code is translated against the canonical ND-100 instruction semantics reference (BSET ZRO/ONE SSK clear/set skip flag, JPL I indirect call, SAA set A, MST PIE mask-set, BSKP ONE SSK skip-if-set, RADD CLD SA DD copy idiom, LDA/LDT ,B frame loads, SAX set X, JMP I indirect return).

Honest caveats

What is byte-proven: GOTAB[57B] = 121246B (prove-mon.py 57 reads commoncode file byte 0xe594 = a2 a6); that value read as a 025-S3IRPIT address is the F1636 stub, whose bytes decode cleanly (173401B = AAX 1). The MPAGE/MPASE shared worker at 102363B in 025-S3IRPIT is real code (first word 174020B = BSET ZRO SSK) and it is a set/get user-parameter routine (monitor entry, SSK-selected copy direction, MOVUS 5-word transfer keyed on the USPAR constant), consistent with GetUserParam and its MPASE SET twin.

What is NOT proven: the F1636 stub lands inside a shared stub block whose own branches leave its window, not a dedicated per-call handler; the actual transfer to MPAGE is the resident CALLPROC in an uncarved overlay. So the MON 57 -> MPAGE attribution rests on the MPAGE symbol name + matching behaviour + the MPASE SET twin, not a followed pointer - hence MISATTRIBUTED in the strict sense. The worker's JPL I/JMP I link cells (102407..102412) are a pointer table whose runtime targets are not resolved here. Confirming the dispatch link needs a live trace: issue a real MON 57, single-step through the stub and the resident CALLPROC, and confirm P lands on MPAGE = 102365 with SSK = 1.

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