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MON 30B (octal) — GetOwnRTAddress (GETRT)

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[30B] = 005650B = GTRT=072036B in segment 025-S3IRPIT, reached by the real dispatch MON 30B -> ENT14(072167B) -> GOTAB[30B]=MFELL(072114B) -> CALLP(032201B) -> MCTAB[30B]=GTRT. Any "GOTAB from commoncode" / "uncarved CALLPROC bridge" / old worker name below is an artefact of the wrong table. Verified: dd if=044-S3IDPIT.bin bs=1 skip=1872 count=2 -> 74 1e. Cross-ref ../317B-ExecuteCommand/README.md and SINTRAN/CARVING-HANDOFF.md sec 3a.

Returns the address of the calling program's RT description. Background programs get the RT-description address of the RT program that controls the terminal. The result is returned in W1 (the A register on the ND-100; MAC example: MON 30 / STA RTPRO). This is an ND-100 monitor call.

Status: GOTAB[30B] = 000000 (byte-proven) — a fall-through: there is no direct GOTAB handler word, so the level-14 handler is reached through the resident MFELL/CALLPROC path (uncarved). There is no ND-100 code worker and no ND-100 named region for this call in the carved segments: the manual short name GETRT resolves only in L07 N500-SYMBOLS (GETRT=106704B, the ND-500 companion). The real worker is tiny — it reads the current RT-description pointer and returns it in A — but that read lives past the uncarved bridge (see Honest caveats). All addresses/values are octal.

Dispatch path

flowchart LR
    A["User program<br/>MON 30B"] --> B["ENT14 level-14<br/>T = MON number"]
    B --> C["GOTAB[30B] = 000000<br/>(fall-through, byte-proven)"]
    C -.uncarved MFELL / CALLPROC.-> D["get-own-RT worker<br/>(uncarved; tiny/inline)"]
    D --> E["RT-description pointer<br/>of running RT program → A/W1"]
    class A blue
    class B,C blue
    class D teal
    class E 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 (C ⇢ D) is the resident MFELL/CALLPROC fall-through — it is not present in any carved segment, so it is the one link that cannot be followed statically. GOTAB[30B] is literally 000000, so there is no entry stub to disassemble; dispatch enters the resident handler, which reads the running RT program's descriptor and returns its address in A/W1.

Code location (dispatch path)

Byte offset = (addr − loadbase) in octal words × 2 (decimal).

Role Segment (full disasm) Addr range (octal) Byte offset Symbol Verdict
GOTAB[30] dispatch word commoncode.asm · .hex 071263B (1 word) 58726 GOTAB+30 = 000000 VERIFIED (fall-through)
resident MFELL/CALLPROC bridge — (uncarved) — — MFELL/CALLPROC UNVERIFIED
GETRT (ND-500 companion) 026-S3IMPIT.asm · .hex 106704B — GETRT (N500-SYMBOLS) MISATTRIBUTED (ND-500 side, not the ND-100 body)

There is no entry-stub row and no ND-100 worker row: GOTAB[30] is 000000, so the level-14 handler is a resident fall-through, and no ND-100 symbol names an RT-address worker body.

Verify by hand: the GOTAB word is a zero (fall-through) — grep '^71263 ' ../../segments-ref/SINTRAN-DATA_commoncode/SINTRAN-DATA_commoncode.hex → 71263 000000 000 000 58726; confirm from the canonical bin dd if=../../../resident/SINTRAN-DATA_commoncode.bin bs=1 skip=58726 count=2 2>/dev/null | od -An -tx1 → 00 00. prove-mon.py 30 reads the same GOTAB zero.

Instruction walkthrough

Full listing: 30B-GetOwnRTAddress.ASM. There is no entry stub (fall-through dispatch) and no ND-100 worker body or named region in the carved segments, so there is no executable walkthrough. GETRT=106704B is the ND-500 companion in 026-S3IMPIT, not the ND-100 worker.

Parameter / register contract

Manual-side names/types are from 30B_GetOwnRTAddress.yaml (MAC form: MON 30 / STA RTPRO).

Reg / field Dir Meaning Verdict
A / W1 out the RT-description address of the calling program inferred (manual)
(background program) — returns the RT program controlling the terminal inferred (manual)

There is no entry stub and no carved worker, so nothing in this contract is byte-proven from executable code; every row is inferred from the manual.

Pseudo-code (for an emulator)

See 30B-GetOwnRTAddress.pseudo.c — a pseudo-C model. Because the call is a fall-through and there is no carved ND-100 worker (GETRT is the ND-500 companion), the model is of the documented behaviour only, NOT carved code. The fall-through MON 30 → worker bridge is modelled but not proven.

Instruction semantics follow the canonical reference: ../../instruction-semantics/ND100-INSTRUCTION-SEMANTICS.md.

Honest caveats

What is byte-proven: GOTAB[30B] = 000000 (level-14 fall-through; prove-mon.py 30 reads commoncode file byte 0xe566 = 00 00). That is the only fact these carved bytes establish for this call.

What is NOT proven: anything about the RT-address worker. Because GOTAB[30] is 000000, there is no stub to follow; dispatch enters the resident MFELL/CALLPROC handler in an uncarved overlay. The manual short name GETRT resolves only in N500-SYMBOLS (GETRT=106704B) — the ND-500-side companion, not the ND-100 body — so it is MISATTRIBUTED to the ND-100 call, and no ND-100 symbol names the worker.

This reconciles into one story: the dispatch head (GOTAB[30]=0, fall-through) is solid; the ND-100 worker is a tiny resident routine (read the running RT program's descriptor, return its address in A/W1) that lives past the uncarved bridge; and GETRT=106704B is the ND-500 companion. Confirming the actual worker needs a live trace (break on a real MON 30, single-step the fall-through, and record where P lands).

Method: ../../../../../EXTRACTING-RESIDENT-CODE.md §9 · dispatch reality: ../../TASK-05-mismatches.md §G · master map: ../../MON-CALL-INDEX.md.