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MON 213B (octal) - GetDirUserIndexes (MUIDI)

Gets a directory index and a user index from a directory-and-user name string (up to 16 characters, e.g. A-HANSEN). These two indices identify a user's files in the file system; other calls (GetAllFileIndexes, GetObjectEntry, WriteDirEntry) take them as input.

Status: GOTAB dispatch head byte-proven as fall-through (GOTAB[213B] = 000000, no per-call stub); the MUIDI worker body is real SINTRAN L bytes and resolves the directory via GDIRI (Get DIRectory Index) and the user via RUSER (Read USER entry) / GUSEI (Get USer Entry Index); the exact MON 213 -> worker link crosses an uncarved kernel bridge (see Honest caveats). All addresses/values are octal.

Dispatch path

flowchart LR
    A["User program<br/>MON 213B"] --> B["ENT14 level-14<br/>T = MON number"]
    B --> C["GOTAB[213B] = 000000<br/>(byte-proven: fall-through)"]
    C -.uncarved MFELL / CALLPROC.-> E["MUIDI get-dir-user-indexes worker<br/>006-S3FS :105012B"]
    E --> F["GDIRI get-directory-index<br/>006-S3FS :47402B"]
    E --> G["RUSER read-user-entry<br/>006-S3FS :53246B"]
    class A blue
    class B,C blue
    class E,F,G 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 GOTAB slot is zero, so there is no per-call entry stub. The dashed hop (C -> E) is the resident MFELL/CALLPROC fall-through second-level dispatch - 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[213] dispatch word commoncode.asm - .hex 071446B (1 word) 58956 GOTAB+213 = 000000 VERIFIED (fall-through)
resident MFELL/CALLPROC bridge - (uncarved) - - CALLPROC UNVERIFIED
MUIDI get-dir-user-indexes worker 006-S3FS.asm - .hex 105012B-105300B (to GUSNA) 48148 MUIDI real bytes; link MISATTRIBUTED
GDIRI get-directory-index 006-S3FS.asm - .hex 47402B (call target) - GDIRI called by MUIDI (link cell 105260) - VERIFIED
RUSER read-user-entry 006-S3FS.asm - .hex 53246B (call target) - RUSER called by MUIDI (link cell 105272) - VERIFIED

Verify by hand: grep '^105012 ' ../../segments-ref/006-S3FS/006-S3FS.hex -> byte offset 48148; then dd if=../../../segments/006-S3FS.bin bs=1 skip=48148 count=8 | od -An -tx1 -> f8 90 22 29 cc 65 cc 59 (= octal 174220 021051 146145 146131 = BSET ONE SSK / STD I 51 / RADD CLD SL DA / RADD CLD SB DD, the MUIDI entry).

The GOTAB slot itself: dd if=../../../resident/SINTRAN-DATA_commoncode.bin bs=1 skip=58956 count=2 | od -An -tx1 -> 00 00 (= 000000, fall-through).

The RUSER link cell: dd if=../../../segments/006-S3FS.bin bs=1 skip=48500 count=2 | od -An -tx1 -> 56 a6 (= octal 053246, the word at 105272B = the resolved RUSER worker address); the GDIRI link cell at 105260B (byte offset 48480) holds 047402.

Instruction walkthrough

Full listing: 213B-GetDirUserIndexes.ASM. The functional body is the MUIDI worker; there is no F16xx stub because GOTAB[213] = 0. All calls to shared file-system workers are indirect (JPL I / JMP I) through pointer tables at 105064-105077 and 105247-105300. nd100-dis renders those pointer words as bogus instructions - they are data (link cells), not code; their contents are the real worker addresses (resolved in the .ASM).

  • Entry prologue (105012-105017) - 105012 BSET ONE SSK sets the mode flag; 105013 STD I 51 stashes the caller's double-word parameter; 105016 SAB 157 builds the 157-word local frame B (name-string buffers); 105017 JPL I 46 -> 003752 is the shared resident prologue worker.
  • Parse the name string (105026-105155) - the directory/user name is parsed and scanned via 105044/105104 JPL I -> 046231 (FLPAR, parameter parse), 105036/105010 JPL I -> 061451 (REMCH, remote-char), 105122 JPL I 132 -> 042237 (SEPST, separator scan) and 105127 JPL I 126 -> 030062 (GETCH, get char). Errors funnel to the store-status exit at 105243.
  • Resolve directory + user (105145-105213) - 105145 JPL I 113 -> 047402 (GDIRI, Get DIRectory Index) yields the directory index; then 105152 JPL I 107 -> 053740 (GUSEI, Get USer Entry Index), 105135/105173 JPL I -> 054527 (GMUSI), 105171 JPL I 73 -> 055111 (GUSEN), 105202 JPL I 65 -> 054130 (GMFKN) and 105207 JPL I 62 -> 053114 (TUSRT) resolve the user, and 105213 JPL I 57 -> 053246 (RUSER, Read USER entry) reads the user entry.
  • Return the indices (105226-105242) - the resolved directory and user indices are packed for the caller (105234-105237 SHA/ADD -> STA ,B 1); 105240 MIN ,B 4 is the success return-link bump; 105243 STA ,B 2 writes the result word into the caller's status slot B+2; every path funnels into the resident return 105242 JMP I 36 -> 003776.

The JPL I 113 call to GDIRI (link cell 105260 = 047402) plus the JPL I 57 call to RUSER (link cell 105272 = 053246) and JPL I 107 to GUSEI (link cell 105261 = 053740) are the byte-level proof that MUIDI is the GetDirUserIndexes worker: it resolves a directory index and a user index from a name string. MUIDI is also the 213B short name in the manual.

Parameter / register contract

Manual-side names/types are from 213B_GetDirUserIndexes.yaml.

Reg / field Dir Meaning Verdict
entry point (worker) in 105012B = MUIDI worker entry VERIFIED (bytes)
SSK (skip flag) internal 1 at entry; latched to B+156 VERIFIED (bytes)
D (double) in caller parameter block, saved first (STD I 51) VERIFIED (copy); layout inferred
local frame B internal SAB 157 = 157B-word working frame VERIFIED (bytes)
X (manual) in address of the directory-and-user name string (up to 16 chars) inferred (manual MAC example)
T (manual) out directory index (STT INDEX left byte) inferred (manual)
A (manual) out user index (right byte of the returned index word); error number on error return inferred (manual)
B+1 internal packed directory/user index result (STA ,B 1 at 105237) VERIFIED (bytes)
B+2 out returned status word (STA ,B 2 at 105243) VERIFIED (bytes)

The user-visible X in / T+A out register convention lives in the caller-side MON 213 wrapper and the uncarved MFELL/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 213B-GetDirUserIndexes.pseudo.c - a pseudo-C model of the handler for emulator authors. Control flow + the calls to GDIRI / RUSER / GUSEI are byte-verified; the parameter-field semantics and error-number meanings are inferred from the call structure and the manual. Every instruction is translated per the canonical ND100-INSTRUCTION-SEMANTICS.md (bare LDA disp = mem[P+disp]; RADD CLD SD DA = A = D; SHA ZIN logical shift; MIN ,B 4 success bump).

Honest caveats

What is byte-proven: GOTAB[213B] = 000000 (level-14 fall-through, no per-call vector); the MUIDI worker body at 105012B in 006-S3FS is real code (entry bytes 174220 021051 146145 146131 match the disassembly, bounded by the next FILSYS symbol GUSNA = 105301B); and it resolves the indices - it calls GDIRI (047402B, link cell 105260), RUSER (053246B, link cell 105272) and GUSEI (053740B, link cell 105261).

What is NOT proven: the link from the zero GOTAB slot to the MUIDI worker. Because the vector is zero there is no stub to disassemble and no pointer to dereference; dispatch drops into the resident MFELL/CALLPROC second-level path, which lives in an uncarved overlay. So the MON 213 -> MUIDI attribution rests on the MUIDI symbol name (the 213B short name) + its GDIRI/RUSER/GUSEI calls + the matching resolve-indices behaviour, not a followed pointer - hence MISATTRIBUTED in the strict sense. Confirming the link needs a live trace: issue a real MON 213, single-step the level-14 fall-through into the resident CALLPROC dispatch, and confirm P lands on MUIDI = 105012.

Region bound: the MUIDI worker is bounded strictly to the next FILSYS symbol GUSNA = 105301B. Several link-cell targets (003752, 020274, 001224, 003776) sit below the 26000B segment load base; they are 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.