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MON 314B (octal) - DefaultRemoteSystem (SDRUS)

Sets the default remote system - the COSMOS network computer searched for a file that is not found locally when remote file access is on (see MON 316B SetRemoteAccess). Only available with COSMOS installed. ND-100 call (manual ND-860228-2 EN, section 2.14).

Status: byte-verified (dispatch + worker body). The worker is real carved code in 006-S3FS. All addresses/values are octal.

CORRECTED 2026-07-13. The previous version of this folder said the worker was misattributed / "not recoverable from these carved bytes", claiming GOTAB[314] = 112326B resolved to a DSI4 device/interrupt routine and that the only matching symbol was the ND-500 SRUSI = 125473B. All of that was an artefact of the wrong dispatch model. MON calls take their worker from MCTAB @ 005620B (segment 044-S3IDPIT), not from that GOTAB (which is MFELL for 224 of 256 calls). MCTAB[314B] = 111501B = SDRUS (byte-proven), and that worker IS carved in 006-S3FS. The DSI4 / "not recoverable" reading came from the disproven "uncarved CALLPROC bridge" story. See ../317B-ExecuteCommand/README.md and SINTRAN/CARVING-HANDOFF.md section 3a.

Dispatch path

flowchart LR
    A["User program<br/>MON 314B"] --> B["ENT14 level-14 entry<br/>026-S3IMPIT :072167B"]
    B --> C["GOTAB[314B] = MFELL<br/>MGOTA=071233B :071547B"]
    C --> D["MFELL level switch<br/>026-S3IMPIT :072114B -> CALLP 032201B"]
    D --> E["MCTAB[314B] = SDRUS<br/>MCTAB=005620B :006134B = 111501B"]
    E --> F["SDRUS worker<br/>006-S3FS :111501B"]
    class A blue
    class B,C,D,E teal
    class 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

There is no dashed hop. GOTAB[314B] = MFELL (byte-proven, 74 4c); MFELL is a program-level switch, not a subroutine call. The monitor level then indexes MCTAB and reaches SDRUS.

Code location (dispatch path)

Byte offset = (addr - loadbase) in octal words x 2 (decimal). Offsets reproduced with dd.

Role Segment Addr (octal) Byte offset Symbol Verdict
GOTAB[314B] slot 026-S3IMPIT.asm 071547B = 072114B 32462 -> MFELL VERIFIED
MCTAB[314B] slot 044-S3IDPIT.asm 006134B = 111501B 2232 -> SDRUS VERIFIED
SDRUS worker body 006-S3FS.asm 111501B-111546B+ 52866 SDRUS VERIFIED

Verify by hand (from tools/sintran-segment-carver/versions/L-VSX-500/segments/): 

dd if=026-S3IMPIT.bin bs=1 skip=32462 count=2 | od -An -tx1   ->  74 4c   (= 072114B = MFELL)
dd if=044-S3IDPIT.bin bs=1 skip=2232  count=2 | od -An -tx1   ->  93 41   (= 111501B = SDRUS)
dd if=006-S3FS.bin    bs=1 skip=52866 count=2 | od -An -tx1   ->  22 29   (= 021051B, SDRUS entry: STD I 51)

Instruction walkthrough

Full listing: 314B-DefaultRemoteSystem.ASM.

Prologue (111501B-111505B). STD I 51 / RADD CLD SL DA / RADD CLD SB DD / SAB 47 save the caller's registers and build the frame; JPL I 46 (-> 111553B) calls the shared FILSYS/COSMOS entry helper.

Staged field stores (111506B-111531B). A repeating four-instruction pattern - LDA <const> / RADD SB DA (form a frame address) / LDX ,B <n> / JPL I <helper> - runs for the caller's operands ,B 1, ,B 2, ,B 3, storing each into the default-remote record via the helper at 111555B, with error branches to 111550B.

Record assembly (111532B-111546B). Loads three resident constants (LDX 22 / LDT 22 / LDA 22), combines them (RADD SB DX/DT/DA, RADD CLD SA DD) and calls JPL I 16 (-> 111561B) to commit the assembled default-remote-system record; an error path uses MIN ,B 4 / SAA -47.

The prologue, the staged stores and the commit call are byte-proven; the exact record layout (system id vs user vs flags) is inferred from the manual and the COSMOS context.

Parameter / register contract

Reg / field Dir Meaning Verdict
,B 1,,B 2,,B 3 in operands staged into the default-remote record VERIFIED (bytes); field meaning inferred
default-remote record out assembled and committed via JPL I 16 (-> 111561B) VERIFIED (structure); layout inferred (manual)
,B 4 out error counter (MIN ,B 4) on failure VERIFIED (bytes)
return out via saved link; error path 111550B VERIFIED (bytes)
availability in COSMOS installed inferred (manual)

Pseudo-code (for an emulator)

See 314B-DefaultRemoteSystem.pseudo.c - the prologue, the staged operand stores and the record-commit call are byte-verified; the record layout is inferred.

Honest caveats

What is byte-proven: GOTAB[314B] = MFELL; MCTAB[314B] = 111501B = SDRUS; the SDRUS entry bytes at 111501B in 006-S3FS match the disassembly (021051B = STD I 51); the worker stages three caller operands and commits an assembled record via a helper.

What is NOT proven: the exact layout of the default-remote-system record, the internals of the helpers at 111553B/111555B/111561B (reached by JPL I, not carved here), and the COSMOS-installed availability precondition (from the manual).

Correction to earlier work. The old folder read the disproven GOTAB, reported GOTAB[314] = 112326B -> DSI4, and concluded the worker was "not recoverable" (only the ND-500 SRUSI = 125473B matched). The byte-proven worker is MCTAB[314B] = SDRUS = 111501B, real carved ND-100 code. The DSI4 / "not recoverable" reading was the wrong-overlay error.

Method: ../../../../../EXTRACTING-RESIDENT-CODE.md - master map: ../../MON-CALL-INDEX.md.