QUDF.ABPA2 producer carve - is DSTBL scaled? (2026-07-23)¶

Question: does SINTRAN scale the BDIO media address (DSTBL = ABPA2 = ABSTrans parameter 2) anywhere between the ABSTrans caller and the DIOC - i.e. is DSTBL a 2KB-page index or a converted 512-byte sector / cylinder-surface address?

Answer: NO scaling on the DOMINO path. DSTBL is the caller's media address copied verbatim, and the DOMINO path deliberately SKIPS the geometry conversion (TOSECT) that the SMD disk path performs. [V]

Overlay: 017-S3SMPIT = 026-S3IMPIT, base 032000B (0x3400). Symbols: ABPA2 = 000017 [SYMBOL-1-LIST], GAPFU = 000744 / GAPFD = 034006 (literal pool of BDMTR, BDIO-DOMINO-DRIVER-CARVE.md section 7).

The path¶

ABSTrans caller (file system) --param list-->  BDMTR 073454B (MTRANS for DOMINO)
   -> GAPFU 000744B  (T=0 / swapping path)   copy param list -> QUDF
   -> GAPFD 034006B  (normal path)           copy param list -> QUDF
   -> level 12 -> STRBDIO/MBUILD             copy QUDF.ABPA2 -> DOMDF.DSTBL
   -> DIOC

GAPFD 034006B - the normal param copier [V]¶

034006  146137  RADD CLD SB DX   ; X := QUDF (que element)
034007  146153  RADD CLD SA DB   ; B := A = caller parameter list
034010  051400  LDT I ,B 0       ; T := param[0]           (ABFUN)
034011  025401  LDD I ,B 1       ; AD := param[1] double    (MEMA1 memory addr)
034012  032014  STF ,X 14        ; QUDF.ABFUN(14):=T, MEMAD(15-16):=MEMA1
034013  025402  LDD I ,B 2       ; AD := param[2] double    (ABP21 = MEDIA ADDR)
034014  022017  STD ,X 17        ; QUDF.ABPA2(17-20) := AD  <-- VERBATIM, no shift/mul
034015  025403  LDD I ,B 3       ; AD := param[3] double    (ABP31 = page count)
034016  022021  STD ,X 21        ; QUDF.ABP31(21-22) := AD  <-- verbatim
034017  044403  LDA ,B 3         ; A := param low word (count)
034020  146151  RADD CLD SA DD   ; D := A
034021  170401  SAA 1            ; A := 1
034022  022023  STD ,X 23        ; QUDF.ABA31(23-24) := (1, count)
034023  146173  RADD CLD SX DB
034024  146142  EXIT

GAPFU 000744B - the swapping param copier (resident commoncode, base 0) [V]¶

Same verbatim media-address copy (bank-switched with SSPTM around each store):

000762  025402  LDD I ,B 2       ; AD := param[2] double (ABP21 media addr)
000764  022017  STD ,X 17        ; QUDF.ABPA2 := AD       <-- VERBATIM
000766  025403  LDD I ,B 3       ; AD := param[3] (ABP31)
000770  022017? STD ,X 21        ; QUDF.ABP31 := AD (022021)

(GAPFU then does extra >>10 / >>6 arithmetic at 000773-001005 to build the physical ABA31 for the swapper's own use - it does NOT touch the ABPA2 copy.)

dd / xxd reproduction (ground rule) [V]¶

Big-endian binaries, word A byte offset = (A - base_word) * 2.

binary	word (octal)	expected	xxd read
SINTRAN-DATA_commoncode.bin (base 0)	000762	025402 `LDD I,B 2`	025402
SINTRAN-DATA_commoncode.bin (base 0)	000764	022017 `STD ,X 17`	022017
017-S3SMPIT.bin (base 032000B)	034013	025402 `LDD I,B 2`	025402
017-S3SMPIT.bin (base 032000B)	034014	022017 `STD ,X 17`	022017

No TOSECT on the DOMINO path [V]¶

BDMTR 073454B (the DOMINO MTRANS entry, carved in BDIO-DOMINO-DRIVER-CARVE.md section 7) calls GETFREE, BRESERVE, GAPFU/GAPFD, WDATA - and never TOSECT. The SMD disk path DOES call TOSECT "to convert disk address to cylinder and surface" (ND-820023-1-EN, "Monitor Level", line ~5012). So the DOMINO path hands the DIOC a LOGICAL media address; the DIOC firmware does its own physical mapping. This is why DSTBL is not a cylinder/surface/sector value.

Conclusion¶

[V] DSTBL = the ABSTrans caller's media address (ABP21), copied verbatim through GAPFU/GAPFD (this carve) and MBUILD (BDIO-DOMINO-DRIVER-CARVE.md) - SINTRAN applies ZERO scaling on the DOMINO path.
[V] The DOMINO path skips the SMD TOSECT geometry conversion.
[V, manual] The DOMINO SCSI device is uniformly 2-Kbyte pages/blocks.
=> DSTBL is a logical 2KB-page/block index; disk byte offset = DSTBL * 2048, transfer length = DNRPG * 2048 bytes. The one hop not byte-carved is the file-system caller's own computation of ABP21, but with no driver scaling and a page-native device it cannot be anything but a page index. Upgraded from [I] to [V-driver-path + strong-I-unit].

Remaining fully-[V] closure (optional): carve the file-system page-transfer routine that issues the ABSTrans call for a DOMINO file and read the ABP21 it forms. Not required for the DIOC emulation.