MON 60 (N500M) Callers - Master Index¶

How the ND-500/5000 Monitor J04 (nd-500-mon-j04.prog, running on the ND-100) drives the ND-500 through the MON 60 monitor call, and which operator command uses which MON 60 subfunction.

Base directory: SINTRAN/ND500/nd-500-mon/mon60-callers/

Primary sources (all claims here are read from these): - Disassembly: SINTRAN/ND500/nd-500-mon/nd-500-mon-j04.prog.asm - Monitor analysis: SINTRAN/ND500/nd-500-mon/nd-500-mon-j04.prog.md (section 5 = the gateway; section 6 = the full 123-thunk / 159-call-site table - the authoritative per-thunk caller list, not duplicated here) - Subfunction names/params: Developer/MON/calls/60B_N500M.yaml

All addresses are OCTAL (ND convention). Facts are marked PROVEN (read from bytes) or INFERRED (reasoned - e.g. command-name to subfunction where the handler was not traced).

1. The mechanism (PROVEN)¶

The monitor never touches the ND-500 bus hardware directly (zero IOX/IOXT). Every ND-500 operation funnels through one MON 60 instruction:

159 call sites  ->  123 thunks (146310..147070)  ->  1 gateway (146244)  ->  1 MON 60 (146256)  ->  SINTRAN

Thunk (3 words, verified): SAA <subfn>; JMP I 1; .word 146244. The SAA loads the MON 60 subfunction code into A; JMP I 1 jumps through the 3rd word (the gateway pointer).
Gateway (146244): builds the parameter block, issues MON 60 at 146256, then JMP 2 = the P+1 return or JPL I 23 = the P+2 return.

CORRECTION 2026-09-01 - this line used to read "JMP 2 = skip return (success) or JPL I 23 = error", and that is WRONG. JMP 2 sits AT 146257, which IS P+1, so calling it "the skip return" mislabels it. Read from the bytes with P-relative addressing: 146263 LDT 21 loads T from 146263+21 = 146304 = 002032B (ECSLOAD); the compare that follows, plus the second against 004017B at 146305, gate 146271, whose tail 146275 JMP -21 lands on 146254 - two words before the MON 60. That is the retry loop, and it hangs off the JMP 2 (P+1) arm. So P+1 (DIRECT) = ERROR, status in A; P+2 (SKIP) = success, which agrees with the byte-proven polarity in the ND-500 bus-interface reference. Also note JPL I 23 jumps to the CONTENTS of 146303 (= 177335), not to 146303, and 146304/146305 are OPERAND WORDS, not code - arming a debugger on them yields a permanent zero. Cost of the old wording: it was quoted as the authority against the correct reference, and three PC-watch arms were pointed at data words on the strength of it. (ND5000UC\docs\OCTOBUS-SWAPPER-STANDOFF-2026-08-28.md section 167.) On error code ECSLOAD (002032B, at 146304) or 004017B (at 146305) it auto-loads the control store and retries - so ANY MON 60 can trigger a control-store load if the ND-500 microcode is not resident. - A call site (verified pattern): the handler sets X := b.-176 (its MON 60 parameter block), stores the subfunction's parameters into the block, then JPL I <disp> where bank1[P+disp] is a POINTER WORD holding a thunk address. Example (PROVEN): 010214 JPL I 71 -> pointer 010305, bank1[010305]=146340 = thunk SAA 7 = SWLOD.

To read any call site: JPL I <disp> -> EA = P+disp -> bank1[EA] = thunk addr -> that thunk's SAA n = the subfunction. The full resolved list is in nd-500-mon-j04.prog.md section 6.

2. Operator command -> MON 60 subfunction¶

The N500: operator commands map to MON 60 subfunctions as below. "Handler call site" is the resolved MON 60 call site from nd-500-mon-j04.prog.md section 6 where PROVEN; where only the subfunction identity is certain (from the yaml) but the exact handler was not traced, the command->subfunction is marked INFERRED.

2.1 ND-500 initialisation / setup (the priority set - carved to folders)¶

Command	Subfn	Name	Thunk	Call site	Status
LOAD-CONTROL-STORE	`037B`	LDCS	`146445`	`006114`	PROVEN
LOAD-SWAPPER	`007B`	SWLOD	`146340`	`010214`	PROVEN
START-SWAPPER	`054B`	STSWP	`146525`	`010217`	PROVEN
GIVE-N500-PAGES	`052B`	G500P	`146517`	`010232`	PROVEN
TAKE-N500-PAGES	`053B`	T500P	`146522`	`010245`	PROVEN
STATUS	`041B`	RSTAT	`146461`	`127566`	PROVEN
PLACE-DOMAIN	`130B`	PLADOM	`146712`	`043171`	PROVEN
DEFINE-STANDARD-DOMAIN	`127B`	DEFDOM	`146707`	`046056`	PROVEN
DELETE-STANDARD-DOMAIN	`131B`	DELDOM	`146715`	`007347`	PROVEN
LIST-STANDARD-DOMAINS	`132B`	LSTDOM	`146720`	`007352`	PROVEN
LIST-EXECUTION-QUEUE	`133B`	LSTEXQ	`146723`	`111445`	PROVEN
LIST-SYSTEM-PARAMETERS	`103B`	RSYSP	`146624`	`073132`	PROVEN
SET-SYSTEM-PARAMETERS	`104B`	WSYSP	`146627`	`073354`	PROVEN
DEFINE-MEMORY-CONFIGURATION	`040B`	DEFM	`146450`	`135361`	PROVEN
MEMORY-CONFIGURATION	`060B`	LIMEM	`146541`	`135532`	PROVEN
MASTER-CLEAR	`035B`	MSTCL	`146456`	`005736`/`005744`/`122514`	PROVEN
MICRO-START	`025B`	MICST	`146415`	`006307`/`130130`/`130361`/`131140`	PROVEN
MICRO-STOP	`034B`	MSTOP	`146453`	`006312`/`122512`	PROVEN
VERSION (microprog vers)	`057B`	MPVER	`146536`	`005577`/`132132`	PROVEN

2.2 Other commands mapped by subfunction (INFERRED from name + yaml unless noted)¶

Command	Subfn	Name	Thunk	Call site(s)
OPEN-FILE (connect)	`013B`	CNCFI	`146351`	`036440`
CLOSE-FILE	`014B`	CLSFI	`146354`	`005123`
LIST-OPEN-FILES	`017B`	LISOP	`146365`	`005157`
SET-BLOCK-SIZE	`141B`	SETBLK	`146742`	`005154`
DEFINE-SWAP-FILE	`045B`	DEFSW	`146475`	(no static caller)
DELETE-SWAP-FILE	`047B`	DELSW	`146503`	`007430`
TIME-USED	`020B`	TIMUS	`146370`	`005162`
WHO-IS-ON	`021B`	WHO	`146373`	`005165`/`007445`
SET-FLAG	`101B`	SPFLAG	`146621`	`005223`
GET-FLAG	`100B`	RFLAG	`146616`	`005264`
SET-PRIORITY	`105B`	SPRIO	`146632`	`006406`/`006444`/`006513`
SET-PROCESS-NAME	`074B`	SPRNM	`146602`	`010112`
ABORT-PROCESS	`117B`	ABORT	`146657`	`110346`
LOGOUT-PROCESS	`122B`	LOGOUT	`146670`	`110355`
ATTACH-PROCESS (link)	`106B`	LNKPR	`146635`	`006711`
PLACE-DEBUGGER	`134B`	PLADBG	`146726`	`002560`
ACTIVATE stopped proc	`136B`	ACTIV	`146731`	`010610`
SET-HISTOGRAM	`062B`	HIDEF	`146544`	`040133`
START-HISTOGRAM	`063B`	HISTA	`146547`	`010440`
STOP-HISTOGRAM	`064B`	HISTP	`146552`	`010435`
PRINT-HISTOGRAM	`065B`	HISTN	`146555`	`040437`
RELEASE-HISTOGRAM	`066B`	HIREL	`146560`	`010443`/`110130`
START-PROCESS-LOG-ONE	`111B`	SLOG1	`146643`	`110161`
START-PROCESS-LOG-ALL	`115B`	SLOGA	`146654`	`110143`
PRINT-PROCESS-LOG (read)	`113B`	RLOG	`146646`	`110116`/`110243`/`110310`
RELEASE-LOG-BUFFER	`114B`	RELLOG	`146651`	`006676`
START-MONCALL-LOG	`124B`	SMONLOG	`146676`	`007312`
PRINT-MONCALL-LOG	`125B`	PMONLOG	`146701`	`111232`
STOP-MONCALL-LOG	`126B`	XMONLOG	`146704`	`007320`
COMPARE/LOOK CONTROL-STORE (read CS)	`023B`	REACS	`146407`	`123556`/`124201`
(write control store)	`024B`	WRICS	`146412`	`123420`
LOOK-AT-PHYSICAL-SEGMENT (read)	`073B`	RPHSG	`146420`	`056407`

Note: several commands issue MULTIPLE subfunctions (e.g. the swapper/paging block at 010200-010260 issues SWLOD, STSWP, G500P, T500P; STATUS reads RSTAT plus MPVER). The per-command folders document the full sequence each handler runs. Commands that do NOT go through MON 60 at all (pure ND-100-side operations, macros, formatting) are not listed.

3. Full thunk table (PROVEN, address -> subfunction)¶

The 123 thunks at 146310-147070, one per source-declared ND-500 interface routine, in declaration order (not numeric order). Duplicate thunks exist for a few subfunctions (006B 007B 036B 037B 050B 073B 151B 152B) - at most one of each pair has a caller. This binary's subfunction space runs 0-177B (FUNCMAX=177), extending ~20 subfunctions past the 94-entry NDInsight yaml (codes above 142B, and 036B/042B/046B/ 107B, are undocumented there). See nd-500-mon-j04.prog.md section 6.2.

The complete thunk -> subfunction -> caller table with all 159 call sites is in SINTRAN/ND500/nd-500-mon/nd-500-mon-j04.prog.md section 6. It is not duplicated here to keep a single source of truth.

4. Per-subfunction folders - COMPLETE (101 folders)¶

Every MON 60 subfunction that has a resolvable caller in this binary is carved into its own subfolder of this directory. 101 folders, 303 files (each folder holds three files: <name>.asm annotated handler/case listing, <name>.pseudo.c C pseudo-code, and README.md with the authoritative purpose, server handler, every call site + enclosing routine, the parameter block filled before the call, skip/error paths, and an explicit unknown/inferred list).

Two naming conventions are used:

8 priority folders are named by operator command (the ND-500 initialisation/setup set): LOAD-CONTROL-STORE/, LOAD-SWAPPER/, START-SWAPPER/, STATUS/, START-STANDARD-DOMAIN/ (subfunction 130B; the operator keyword PLACE-DOMAIN was NOT confirmed - named by authoritative purpose), LIST-STANDARD-DOMAINS/, LIST-SYSTEM-PARAMETERS/, LIST-EXECUTION-QUEUE/.
93 folders are named <CODE>B-<MNEMONIC> (e.g. 037B is covered by LOAD-CONTROL-STORE/; 012B-RUNN/, 144B-CHANGE-CPU/, 170B-READ-CPU-TYPE/, ...). Operator-command keywords were deliberately NOT invented for these - the bank-2 command-string table was not consulted, so they are named by subfunction to avoid guessing.

Undocumented subfunctions (no FUNCTION= comment in the NPL, generic 5NOPAR dispatch) are named <CODE>B-UNDOC/: 036B 155B 162B 163B 164B 165B 167B 171B.

Verification (all folders): every call site's JPL I <disp> was resolved bank1[P+disp] -> thunk -> SAA <code> from the bytes; octal=hex=decimal cross-checked; error/success return polarity applied per nd-500-mon-j04.prog.md section 5.4; ASCII-only; no fabricated names (unknowns are labelled). See each folder's README for its proven-vs-inferred split.

5. Open items¶

22 thunks have no statically resolvable caller (listed in nd-500-mon-j04.prog.md section 6.1). They are either dead or reached through a frame-relative JPL I ,B <disp> dynamic dispatch a static resolver cannot follow. UNKNOWN.
~20 subfunctions above 142B are undocumented in the NDInsight yaml. Their identities need the SINTRAN 5IFUNC dispatch table at 5P-P2-MON60.NPL:1405-1575. UNKNOWN here.
INFERRED command->subfunction rows (section 2.2) map by command name + yaml purpose; the exact handler function was not traced for those. To promote to PROVEN, trace the handler enclosing each listed call site (as done for the priority set).