MF-controller)¶

What SINTRAN III (M06 generation) actually sends and expects on the octobus, cataloged from the NPL source, the M06 symbol tables and the carved L-VSX-500 driver bodies. This is the "what will the OS throw at our emulated stations" reference for RetroCore.

Evidence markers: [V] = verified in source/symbols/carve, [I] = interpretation, [UNCERTAIN] = explicitly open.

Companion docs: - OCTOBUS-ND100-ND5000-REFERENCE.md - frame format, CM* codes, kicks, idents - OCTOBUS-TEST-PROTOCOL-RE.md - the OMD-0 test protocol (TPE, not SINTRAN) - HANDOFF-OCTOBUS-EMULATION.md - emulation plan phases 1-4

Primary sources (all paths repo-relative): - ../NPL-SOURCE/NPL/MP-P2-N500.NPL - kick sender, multibyte builders, receive dispatcher - ../NPL-SOURCE/NPL/RP-P2-N500.NPL - 5PIT bring-up ladder (XX5CONOMD) - ../NPL-SOURCE/NPL/PH-P2-OPPSTART.NPL - SINTR startup probe (CH5CPUPRESENT), OCSTART tables - ../NPL-SOURCE/NPL/CC-P2-N500.NPL - monitor-level entry points (CALLROUT), 5OCTOSWITCH - ../NPL-SOURCE/SYMBOLS/M06/ - constant values (SYMBOL-1-LIST, N5000-SYMBOLS) - ../../tools/sintran-segment-carver/versions/L-VSX-500/re/segments-ref/026-S3IMPIT/026-S3IMPIT.asm - carved L driver bodies

1. The multibyte message descriptor (LMFIELD record) [V]¶

Every SINTRAN-built octobus multibyte message is described by a word record (built in the working field "LMFIELD", handed to MBSEND). Word offsets from the M06 symbol tables (values octal):

Offset	Symbol (5-char)	Field	Notes
0	MOCTS	MOCTSTATION	destination (or reported source) station number
1	MOCTO	MOCTOMD	destination OMD number
2	MBROA	MBROADCAST	0 = not broadcast
3	MMSGL	MMSGLENGTH	message length in BYTES
4	MCOMM / MSTS	MCOMMAND / MSTS	command or status byte in the HIGH byte (NPL idiom `CMxxx SHZ 10 =: X.MCOMMAND`)
5	MDP1	MDP1	first parameter word
4 (recv)	ETYPE	ETYPE	received: high byte = SEC/status, low byte = reporting source

Received-record extras (5OMBREAD / 9FLER): the L07 carve (2026-07-19, OCTOBUS-DRIVER-ROUTINES-CARVE.md) byte-proves the 9FLER record stores the SEC code at LMREC+2 and the source station at LMREC+3 [V]. The earlier "EOCTSOURCE = offset 1 / ESECCODE = offset 0" reading here came from M06 symbols and may be relative to a different record base - [UNCERTAIN] until re-verified against M06 bytes; for L07 use +2/+3. N5SECCODE = 2000B is OR-ed into the SEC code as the "ND-500 class" tag. [V]

MBSEND takes the record plus a physical address/bank ("LMFIELD+DPITPHYS"=:D; A:=DPITBANK) and puts the message on the wire; the multibyte wire envelope itself (SOMB 0x30|OMD, srcOMD, byte count, payload bytes, EOMB 0x20|OMD) is byte-verified in OCTOBUS-TEST-PROTOCOL-RE.md section 1. [V]

2. Station and OMD assignments [V]¶

From M06 SYMBOL-1-LIST / N5000-SYMBOLS (values octal):

Symbol	Value	Meaning
(card)	1	ND-100 CPU station
FMFDEST	2	first MF-controller station
LMFDEST	6	last MF-controller station
FN5DEST	70	first ND-5000 (SAMSON) CPU station
LN5DEST	73	last ND-5000 CPU station in M06 (4 SAMSONs). L07 = 77B [V 2026-07-19 carve, 5OMBREAD range check] - the hardware station table allows 70-76B; per-build constant
OMDACCP	3	OMD on the SAMSON consumed by the ACCP command library
MFOMDNO	4	OMD on the MF-controller for host messages
N100IDENT	1	the ND-100's octobus IDENT number
CMSYSPAR	16	command: write system parameters
CMCPURES	71	command: reset CPU
CMMACLE	41	(emergency base) master clear
CMACONT	42	(emergency base) continue ACCP
MFACK	0	ack status
MFNACK	377	nack status
N100KICK	1	kick: activate ND-5000 process
CLRKICK	3	kick: execute clear-functions mask
IDLEKICK	6	kick: save context / go idle
N5SECCODE	2000	SEC-code class tag for ND-500 errors

Per-CPU station assignment: X.CPUNO + FN5DEST - 1 =: X.5STATION (RP-P2-N500.NPL:976), i.e. SAMSON CPU n sits at station 70B + n - 1. [V]

The ND-100's own receive OMD (5OMDNO, offset 0 of the driver datafield LMDF) is allocated at runtime by CONOMD - it is NOT a fixed constant. [V]

3. Kicks (single control frames) [V]¶

Send path: XKICK500 (MP-P2-N500.NPL:3278-3316). If not already on level 12 it switches there (IRW LV12B, MST PID), then LV12KICK runs T:=5STATION; X:=OCTORING; A:=CKICKTYPE; CALL SKICK. Errors log 9ERR(#99). Return to the calling level goes via a level-14 helper (LV14KICK) that temporarily masks lower levels. [V]

Kick	Value	Sent by	When
N100KICK	1	XACTRDY (ACT52, MP-P2-N500.NPL:3032)	activate the ND-500: a message is waiting and a CPU is idle or lower-priority
CLRKICK	3	LMPCLR (MP-P2-N500.NPL:1231), ST0PSYS (MP-P2-N500.NPL:3769)	execute the clear-functions mask just written to mailbox word X5CLR (clear tsb/cache/dump/forget-process; ST0PSYS writes mask 77B)
IDLEKICK	6	XTER500 TER51 loop (MP-P2-N500.NPL:2950)	ask a running CPU to save context and go idle (termination), polled with GETC5PROC

Kick frame format (C=1, K=1, kick number in low bits) and the microcode dispatch (OCB_DEC_K) are in OCTOBUS-ND100-ND5000-REFERENCE.md. [V]

4. Multibyte messages the ND-100 SENDS [V]¶

4.1 XRS5CPU - "Reset CPU" (MP-P2-N500.NPL:3328-3343)¶

To (5STATION, OMDACCP=3), not broadcast, MMSGLENGTH=1: MCOMMAND = CMCPURES(071B) << 8. Sent via MBSEND on level 12. Used by RS5CPU (level-1 5PIT) for every alive-but-inactive SAMSON. [V]

4.2 MFPREPARE - give the MF-controller our OMD (MP-P2-N500.NPL:3586-3598)¶

To (MF station 2..6, MFOMDNO=4), MMSGLENGTH=3: MCOMMAND = CMSYSPAR(016B) << 8 | N100IDENT(1), MDP1 = 5OMDNO << 8. "Sends OMD number to mf-controller on which N100 can receive messages." Ack/Nack answer handled by 5OMBREAD. [V]

4.3 CON5IDENT - the SAMSON LSYSPAR handshake (MP-P2-N500.NPL:3614-3634)¶

Per alive SAMSON CPU, from level 1 via level 12: 1. ECONID connects octobus IDENT N100IDENT(1) to the LV12 driver (N100IDENT=:D; LV12B SHZ -3; CALL ECONID). [V] 2. Builds to (5STATION, OMDACCP=3), MMSGLENGTH=7: MCOMMAND = CMSYSPAR(016B) << 8 | N100IDENT(1), S5 = 5OMDNO << 8, S6 = S7 = 0; CALL MBSEND. [V]

This is the "write system parameters" (manual LSYSPAR, ND-05.020.01 ch. 5.3.13) message: it tells the ACCP which station/ident/OMD the host listens on. Comment in source: "Send 'alive' message to the ACCP to verify that it's present". [V]

The ACCP MUST ANSWER this message with an Ack - 5OMBREAD treats the Ack/Nack "on 'WriteSysPar' message" as "I'm present" and only then sets CPUAVAILABLE BONE 5ALIVE (MP-P2-N500.NPL:3467-3471). No ack = SAMSON never becomes alive to SINTRAN. [V]

4.4 MF error-record acknowledge (MP-P2-N500.NPL:3523-3532)¶

After forwarding an MF-controller error record to 9FLER, if the source was an MF station (2..6): reply to (source station, MFOMDNO=4), MMSGLENGTH=1, MSTS = MFACK(0) << 8. "Mf-controller requires ack message." [V]

5. Messages the ND-100 RECEIVES - 5OMBREAD dispatch [V]¶

5OMBREAD (MP-P2-N500.NPL:3453-3536) is activated when a multibyte message arrives on the reserved OMD (5OMDNO). It reads the message with OMBREAD and dispatches on the SOURCE station in MOCTSTATION:

Source in FN5DEST..LN5DEST (a SAMSON, 70B-73B): - ETYPE high byte =: CSTS (status/SEC), low byte =: CMICP (reporting source). - CSTS=MFACK(0) or MFNACK(377B): Ack/Nack on WriteSysPar -> set 5ALIVE, done. [V] - Known error codes (CSTS masked 17B < 17B) indexed into MPFATAL (1,0, 0,1, 0,0, 0,0, 0,1, 1,0) - a nonzero entry forces XRSTARTALL with CSTS \/ N5SECCODE. [V] - CMICP=1 (microprogram) with CSTS=200B (HW-fault) or 201B (general trap): the record carries the extended mp error record (process no, trapping/ restart P, trap no, MMS status, logical/physical address, ...); the shadow-process id is patched in and the record goes to 9FLER. [V] Record layouts are spelled out in the 5OMBREAD header comment (MP-P2-N500.NPL:3390-3450): accp record (errcode 200B hwfault, errtype 1=accp), mp record (errtype 2), mf record (etype + emainstat + errlog1-4 + master/slave/address/syndrome). [V]

Source in FMFDEST..LMFDEST (MF-controller, 2-6): - ETYPE=MFACK: ignored (ack for something we sent). [V] - Else: error record -> 9FLER; SEC code = etype; MF codes documented in the header comment: 14B+ prefix, then 20B corrected memory error, 30B memory timeout, 31B unknown error, 50B memory write parity, 51B memory I/O error, 77B fatal MF-controller error. Reply MFACK (section 4.4). [V] - Octobus read errors from OMBREAD itself (A != 101410B) are logged as SEC code with station 0. [I on the 101410B magic - looks like the "no message" status, not verified]

6. Startup sequences [V]¶

6.1 SINTR cold start - CH5CPUPRESENT (PH-P2-OPPSTART.NPL:3903-3945)¶

Per generated ND-500 CPU datafield: 1. Try the OLD ND-500 interface first (IOXT on HDEV+RSTA5 with IOX-error trapped): success -> mark OLD500 + 5ALIVE. [V] 2. Otherwise probe the octobus card: IOXT read 100406 (output controller status) with IOX-error trapped. Present -> busy-wait until status bit 3 (ReadyForTransfer) is set, then: - 5STATION := ASTATION \/ COMD (station for this CPU df), - send emergency (station << 8) | CBIT | EBIT | CMMACLE (= master clear Samson system) via IOXT write 100405, - send ... | CMACONT (= continue accp, starts the ACCP self-test), - set MIFLAG MUDOM bit and CPUAVAILABLE := SAMSON. [V]

This is the origin of the live-verified LIST-HA-CO probe pattern (242B emergencies) and of the "kick 1/3/6 three-way" bring-up. Note SINTRAN talks to the card DIRECTLY with IOXT here - the driver tables are not up yet. [V]

6.2 OCSTART - octobus driver tables (PH-P2-OPPSTART.NPL:4032-4082 + CENTRY/CBPOOL)¶

OCSTART (called from the startup chain at PH-P2-OPPSTART.NPL:1409) handles ONLY interface 0 ("THIS OCTOBUS DRIVER ONLY HANDLE ONE OCTOBUS INTERFACE (DEVICE 0)", source comment). It allocates physical memory for: - receive buffer pool (CBPOOL: MBYA1/MBYA2/MBLINK descriptor chain, OBSIZE bytes per buffer), - ident-entry tables per source station (SOUIDEN, stations 0..77B, each entry = OLINK/DLEVE/DFADD triplet), - 16 OMD entries (OMDENT(0..17B)) and 16 kick entries (KICKENT(0..17B)), each also OLINK/DLEVE/DFADD. [V]

The OMDENT/KICKENT tables are how incoming multibyte messages and kicks are routed to driver datafields on level 12; CONOMD allocates an OMD entry and returns its number (=> 5OMDNO), ECONID binds an ident entry to a level. [V, table mechanics; exact entry semantics beyond the three zeroed words are [UNCERTAIN] pending carve analysis of CONOMD/ECONID bodies]

6.3 5PIT warm bring-up - XX5CONOMD (RP-P2-N500.NPL:944-999)¶

Runs on the 5PIT (level 1) with per-step level-12 calls and MON 2HOLD waits: 1. CON5OMD once (if 5OMDNO=0): connect the receive OMD. [V] 2. If connected: MFPREPARE(station) for EVERY MF station 2..6 - absent controllers simply never answer. [V] 3. Per SAMSON CPU df: set 5STATION, then CON5IDENT (section 4.3); the Ack routed through 5OMBREAD sets 5ALIVE. [V] 4. Count NSAMSON / N5CPU; a CPU with HDEV=660B is disabled on logical device number overlap (546D terminal group 4 check). [V]

7. Monitor-level entry points and the level switch [V]¶

CC-P2-N500.NPL:179-203: monitor-level names KICK500 / TER500 / IACT500 / ACTRDY / RSTARTALL / 5CONOMD dispatch through CALLROUT to the MP-P2 routines (0KICK500, 05CONOMD, ...). [V]
CC-P2-N500.NPL:612-622: 5OCTOSWITCH - the register-preserving trampoline used to jump between the octobus command context and Mpit routines. [V]
ST0PSYS (STOP-SYSTEM command, MP-P2-N500.NPL:3759+): writes clear-mask 77B into mailbox X5CLR then CLRKICK per active SAMSON, then polls X5CLR until the ND-5000 has executed the functions (bounded loop 1000B). [V]

8. Carved driver bodies (L-VSX-500, 026-S3IMPIT) [V addresses]¶

In-kernel L addresses (carve) vs M06 symbol addresses (all octal):

Routine	L carve @	M06 symbol	Role
SOCTO	035546	SOCTO=036176	send single octobus frame
SOCTW	036342	SOCTW=036772	send octobus frame + wait [I from name]
SKICK	037254	SKICK=037704	send kick; carve shows `BSET ONE SSK` then a body SHARED with SIDEN (037256 `BSET ZRO SSK`) - kick vs ident is a one-flag variant of the same sender [V]
MBSEND	037425	MBSEN=040055	send multibyte message. NO IOXT in MBSEND [V 2026-07-19]: validates (station 1..76B, OMD <=17B, length 1..255 bytes), pops a CBPOOL buffer, queues on the TX datafield, and if idle fires level 13 with P:=SOCTW (036342) to transmit. The IOXT block at 037320+ belongs to SKICK's direct-TX path (control:=4 / frame / control:=1), not MBSEND - the earlier reading of this row was wrong. Full body: OCTOBUS-DRIVER-ROUTINES-CARVE.md
OMBREAD	037660	OMBRE=040310	read received multibyte message into buffer
CONOMD	040062	CONOM=040512	connect/allocate an OMD entry
ECONID	040467	ECONI=041117	connect an ident entry to a level

Full instruction-level RE of these bodies is still OPEN - the calling contracts above (registers in/out, record layouts) are what the emulator needs and are NPL-verified.

9. ND-500-MON J04 [I]¶

The ND-500 monitor J04 symbol area contains AEOCTOBUS (address-error source enum SINTRAN/OCTOBUS/NUCLEUS) and PMMESSACK/PMMESSNAK - the octobus generation is represented in its error/ack model, but no octobus driver paths in J04 have been analyzed yet. See ../ND500/nd-500-mon/nd-500-mon-j04.prog.md. [I]

10. What this means for the RetroCore emulation¶

Ordered by when SINTRAN will hit it:

CH5CPUPRESENT probe: card must IOXT-respond on 100406 with RFT (bit 3) and accept emergency 241B/242B to the SAMSON station. IMPLEMENTED (OctobusND5000Station handles both emergencies). [V]
CONOMD/ECONID: pure ND-100-side table management - no wire traffic expected [I from NPL; verify when carving the bodies].
MFPREPARE to stations 2-6: no MF-controller emulated -> frames to absent stations must produce Ack=00 timeout (implemented in OctobusFabric). [V]
CON5IDENT / CMSYSPAR to (SAMSON, OMD 3): OctobusND5000Station already parses CMSYSPAR and stores the system parameters - BUT it does NOT yet send the Ack multibyte back. Without that Ack, 5OMBREAD never sets 5ALIVE and the SAMSON stays dead to SINTRAN ("No ND-500(0) CPU found"). Reply shape RESOLVED [V], 2026-07-18 - see CARVE-ANSWER-OCTOBUS-CPU-PRESENCE-2026-07-18.md: send a multibyte message on OMD 5OMDNO (= the CMSYSPAR body S5 field = byte[4] = 3) from the SAMSON station whose command/ETYPE word high byte = MFACK(0) (MMSGLENGTH=1, ETYPE=0x0000 suffices). 5OMBREAD then does CPUAVAILABLE BONE 5ALIVE at MP-P2-N500.NPL:3470 (146616). Boot's CH5CPUPRESENT sets only CPUAVAILABLE:=SAMSON (interface type), never 5ALIVE - the alive handshake is @nd-500's CON5IDENT, not boot. [V]
Kicks 1/3/6 to the SAMSON station: delivered via AOB with ATRAP+OMESS when kicks enabled. IMPLEMENTED. [V]
ND-5000-originated error records (hw-fault 200B / trap 201B) and Messack/Messnak: handoff phase 4.
ACCP command library on OMD 3/4 (CS-load → microstart): RESOLVED [V] 2026-07-18 — see CARVE-ANSWER-OCTOBUS-CSLOAD-MICROSTART-2026-07-18.md. Two commands read back STATE and cannot be canned:
- VPARP (022B/0x12, §5.3.16) must return ack + the 32-bit word read back from MFbus memory at the LPARP (021B/0x11) pointer (trace pointer = 0x00018000). Canned/zero answer → "Verification of ACCP parameter pointer failed". Store the LPARP pointer, echo _mpmRam[pointer].
- CMALI / ALIVE CHECK (037B/0x1F, §5.3.26) encodes running-state: Messack = micro RUNNING, Messnak-7 = NOT running. After a 244B TERMINATE SINTRAN expects Messnak-7; a canned Messack → "ACCP was terminated; Microprogram is running". Track a _microRunning flag (TERMINATE/STOPMIC 034B/master-clear → false; STARTMIC 033B → true).
- Observed OMD-3 init prologue (all else = Messack): DISKICK 062B, STOPMIC 034B, CPURES 071B, LPARP 021B, VPARP 022B; then LOCSM, STARTMIC 033B.

Created: 2026-07-17. Sources: SINTRAN III s3vs-4 NPL + M06 symbols + L-VSX-500 carve. Author of record for follow-up: see HANDOFF-OCTOBUS-EMULATION.md.