Skip to content

07 - Internals and Monitor Calls

This document is the programmer / kernel view of spooling: the monitor calls a program uses to drive it, and the SINTRAN segments that implement the spooling machinery.

The byte-verified carve is done. The detailed, address-level results now live in 07a-CARVED-INTERNALS-FINDINGS.md. This document is the readable summary; 07a is the ground truth (every address re-read from carved bytes). Where the two differ, 07a wins.

Sources: ../../Reference-Manuals/SINTRAN-COMMANDS-REFERENCE.md and ../../Reference-Manuals/ND-860228-2-EN SINTRAN III Monitor Calls.md (MON-call mappings + register conventions); the L-VSX-500 carve (see 07a).

1. Monitor calls behind spooling

Three monitor calls drive spooling. All three dispatch through MCTAB (the byte-verified dispatch model) and all three workers live in the file-system segment 006-S3FS - which is where the real spooling queue manager is (NOT in segment 031 or 137; see section 2). Byte-verified in 07a:

Monitor call Number (octal) MCTAB slot -> worker Meaning
APSPF MON 240 006060B -> 106307B Append a file to the spooling queue (behind @APPEND-SPOOLING-FILE).
SPCLO MON 40 005660B -> 067572B Close a spooling file (link it to the queue).
GetSpoolingEntry (RSPQE) MON 55 005675B -> 106212B Pull and remove the next queue entry (the spooler uses this).

Register / parameter conventions (verified vs the Monitor Calls manual)

APSPF (MON 240) - AppendSpooling: - X = address of the file name to print (may be abbreviated). - T = number of copies in bits 0:14; bit 15 = 1 also prints the UserText. - A = address of the UserText message (then copied so D = message address). - A = address of the spooling-device peripheral-file name (loaded last). - Return: A = error code (0 = OK). (Worker saves D first = the message pointer, byte-confirmed.)

SPCLO (MON 40) - CloseSpoolingFile: - T = file number (from the earlier open). - A = number of copies (then copied so D = number of copies). - A = condition/print flag (0 = print text only if the spooling conditions require; non-zero = print unconditionally). - X = address of the error-device text. - Return: A = error code. If the file is not a spooling file, a normal close is done. (Worker tests T, byte-confirmed = the file-number parameter.)

So a program can spool without the @ commands: write to the spooling file, SPCLO to close/queue it, or APSPF to append an existing file.

2. Which segment does what (byte-verified)

The carve corrected the naive assumption that the spooling segments (031, 137) hold the queue logic. They do not. The real layout (07a):

Piece Segment Role
Queue manager (APSPF/SPCLO/RSPQE workers, queue list handlers, page-pool wait/wake) 006-S3FS (base 26000B) The actual local spooling engine.
Physical line-printer driver (IOX 430B-433B cells) 044-S3IDPIT / 053-S3SDPIT (DPIT image/save) Per-device IOX cells; the device number lives in the datafield.
Spooling datafield SAVE area 031-S3SSPD (K/L/M) Saved copy of each SPPRx/SPRTx spooling-program datafield - data, not code. This is the <save-area?> operand of *SET-SPOOLING-DEVICE-NUMBER.
Remote (COSMOS) spooling 137-COSPOOL (L only) Holds COSPO, the COSMOS remote spooling RT program (prints to other systems over XMSG). Contains zero IOX/MON words - a separate subsystem, not the local engine.
Local spooling-program body (the routine SPRTx runs) NOT located 120-S3SPRMA (L/M only) is a candidate but its content is not overlay-proven. See 07a.

Key data structures (verified)

  • Per-spooler control block: array SPTAB=122562B..ENDSP=123034B, stride SPLEN=12B (~17 slots), one per device. Fields include SPERI=+2 (peripheral logical device number; -1 disables), SPINX=+10B (spool index), SPAGE=+31B.
  • Per-file queue entry: linked records in a dedicated spool-queue segment (VA 150000B-177777B), list head LSPOQ=162122B; walked by RSPQE=106212B. A queued file is not stored in the normal open-file object tables.
  • Page-pool wait/wake: a SINTRAN semaphore reserve/release at 006-S3FS 171001B-171013B - MON 122B (2RESR) blocks the writer when the pool is empty, MON 123B (2RELE) wakes it, on SPSEM=164607B. Pool free-buffer gate = SPOOL=147510B (=0 means no buffers free).

3. What is resolved, and what is still open

Most of the original open questions are now byte-verified in 07a-CARVED-INTERNALS-FINDINGS.md:

  • Resolved: APSPF/SPCLO/RSPQE dispatch and workers (all in 006-S3FS) and their register conventions; the two queue structures (SPTAB per-spooler block; LSPOQ per-file queue in the spool-queue segment); the page-pool wait/wake semaphore; segment roles (031 = datafield save, 137 = COSMOS remote, 006 = the engine); and the line-printer IOX cells for device 430B/434B in DPIT.

Still NOT RESOLVED (open for a future carving pass, all listed in 07a section 6):

  1. The resident "spooling device numbers" table that *SET-SPOOLING-DEVICE-NUMBER writes (distinct from the verified SPTAB).
  2. The byte location of the common spooling-program body the SPRTx RT programs run (120-S3SPRMA is a candidate but not overlay-proven; the SPOOL symbol is the pool gate, not the program).
  3. The exact decrement->block / increment->wake instruction ordering around the verified reserve/release primitive.
  4. The byte-level unlink of the currently-printing entry from LSPOQ.
  5. The generic line-printer driver code body that executes the DPIT IOX cells.

4. Resolving the remainder (carving)

The remaining items live in the SINTRAN III image, reachable through the sintran-carving skill and the segment carver under ../../tools/sintran-segment-carver/. Record any new byte-verified result in 07a-CARVED-INTERNALS-FINDINGS.md and update this summary accordingly.