MON 437B (octal) - GetND500Param (5PAGET)¶

Gets the five per-background-user parameters that record why the last ND-500 program terminated (user / directory index, terminal device, error code, and two user-defined words); the companion MON 436B SetND500Param sets them. It is an ND-500 monitor call (manual: ND-500 only, not callable from the ND-100 side).

Status: the S3SM5 numeric vector slot for 437B is byte-proven empty (slot 0x029E = 0x0000, inside the 422B-440B zero run), so no handler code exists in the carved 030-S3SM5 segment; the ND-100 GOTAB[437] read is a coincidental hit into the device-table (DT86R), not a handler; and the actual servicing point is NOT LOCATED / UNVERIFIED. All addresses/values are octal unless a 0x prefix or (dec) marks them hex/decimal.

No code body: this call has no worker in any carved segment - there is no .ASM and no .pseudo.c here. The table below documents the absence.
Bytes live once in the canonical segment layer: ../../segments-ref/ (segment 030-S3SM5, load base 40000B).

Dispatch path¶

flowchart LR
    A["ND-500 program<br/>CALLG GetND500Param,1,Buffer<br/>(37B9 + 437B)"] --> B["ND-500 monitor entry<br/>MCNO = 437B"]
    B --> C["S3SM5 0x60 vector table<br/>slot 0x029E = word 40517B"]
    C -.slot = 0x0000, no handler.-> D["serviced elsewhere<br/>(ND-100 back-end, UNCONFIRMED)"]
    X["ND-100 GOTAB[437]<br/>= 056613B = DT86R (device table)"] -.MISATTRIBUTED<br/>device-table data, not code.-> B
    class A blue
    class B,C teal
    class D green
    class X blue
    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 where a real call would jump to its handler word; for 437B that word is 0x0000, so no jump target exists inside 030-S3SM5. The X -> B hop marks the ND-100 GOTAB[437] read as a red herring - 056613B is DT86R, one entry of the regular device-table series (DT01..DT99, 11-word stride), not a handler. Where the call is actually serviced is not carved here (see Honest caveats).

Code location (dispatch path)¶

030-S3SM5 holds a numeric MON-dispatch vector table based at byte offset 0x60. The slot for MON number N is at byte 0x60 + 2*decimal(N). Byte offset -> segment word address = load base 40000B + (offset / 2) words.

Role	Segment (full disasm)	Addr / slot	Byte offset (dec)	Symbol	Verdict
GOTAB[437] read (does NOT apply)	commoncode.asm · .hex	`071672B` (=071233B+437B)	59252	reads `056613B` = `DT86R` (device table)	MISATTRIBUTED - coincidental read into device-table data, not a handler
ND-500 monitor entry (numeric dispatch, `MCNO=437B`)	- (uncarved ND-500 resident)	n/a	n/a	ND-500 MON entry	UNVERIFIED
S3SM5 `0x60` vector slot for 437B	030-S3SM5.asm · .hex	word `40517B` (slot `0x029E`)	670	(empty)	VERIFIED empty (`0x0000`)
Worker body	none in `030-S3SM5`	n/a	n/a	expected ND-100 back-end (not located)	UNVERIFIED

Slot byte offset = 0x60 + 2*decimal(437B) = 96 + 2*287 = 670 (dec) = 0x029E.

Verify by hand (empty S3SM5 slot): grep '^670 ' ../../segments-ref/030-S3SM5/030-S3SM5.hex -> 670 000 (and 671 000); then dd if=../../../segments/030-S3SM5.bin bs=1 skip=670 count=2 | od -An -tx1 -> 00 00. The whole 422B-440B slot run reads 0x0000, while 410B-421B and 446B hold non-zero handler words - so the empty slot is a genuine "no S3SM5 handler".

Verify by hand (GOTAB[437] is device-table data):

grep '^71672 ' ../../segments-ref/SINTRAN-DATA_commoncode/SINTRAN-DATA_commoncode.hex
# -> 71672  056613  135 213  59252     (value 056613B = DT86R)
grep -oE 'DT8[0-9][RW]=[0-7]+' ../../../../../../../SINTRAN/NPL-SOURCE/SYMBOLS/L07/SYMBOL-2-LIST.SYMB.TXT | sort -u
# -> DT85W=056600 DT86R=056613 DT86W=056626 DT87R=056641 ...  (11-word stride device table)

Instruction walkthrough¶

There are no instructions to walk - the vector slot is 0x0000 (data, not a jump target), so no worker body was carved and there is no .ASM. The ND-100 GOTAB[437] value (DT86R) is a device-table datafield, not code, so it is not walked either. For a populated neighbour the ND-500 monitor would index the 0x60 table and transfer to the 16-bit handler word found there (e.g. 411B -> 0xBB38, 446B -> 0xC1F0); slots 422B-440B are all 0x0000.

Parameter / register contract¶

From 437B_GetND500Param.yaml and the manual (ND-860228.2 EN, p.259); not byte-proven here because no handler was located.

Field	Dir	Meaning	Verdict
call form	in	ND-500 `CALLG GetND500Param, 1, Buffer` (`37B9 + 437B`)	manual (inferred)
`Buffer`	out	5-word array receiving: [0] user/dir index, [1] terminal device, [2] error code, [3][4] user-defined	manual (inferred)
availability	-	ND-500 only; not callable from the ND-100 side (see GetUserParam for the ND-100 equivalent)	manual (inferred)
handler slot	-	S3SM5 vector `0x029E` = `0x0000` (no ND-500 handler in this segment)	VERIFIED (bytes)

Honest caveats¶

What is byte-proven: the S3SM5 0x60 vector slot for MON 437B, at byte offset 670 (segment word 40517B, slot 0x029E), reads 0x0000 in the real SINTRAN L bytes of 030-S3SM5.bin. The whole 422B-440B slot run is 0x0000, while 410B-421B hold non-zero handler words - so the empty slot is a genuine "no S3SM5 handler", not a carve artefact. Separately, the ND-100 GOTAB[437] read (056613B = DT86R) is a device-table datafield, proven by its regular DT85W/DT86R/DT86W/DT87R neighbours (11-word stride) - the same coincidental device-table hit seen for the ND-500 call 410B (DT74W), not a handler.

What is NOT proven: where MON 437B is actually serviced. A 0x0000 S3SM5 slot means "not routed to this segment"; the manual marks the call ND-500-only and points the ND-100 side to GetUserParam, so the expected back-end is an ND-100-side companion, but that handler has not been located or carved. Confirming the real dispatch needs a live trace of an ND-500 GetND500Param call, or locating the ND-100 back-end that consumes it. Until then this folder correctly holds no code. This reconciles into one story: the S3SM5 slot is verified empty and the GOTAB read is a verified misattribution, while the worker is unverified/absent - consistent, not contradictory.

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