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01 — Disk Devices & CREATE-DIRECTORY Mapping

Status: SCAFFOLD.

Scope / precondition

This guide assumes the target disk is already correctly formatted. Disk formatting (with the proper ND tools) is out of scope and currently undocumented.

For the emulator, formatting is irrelevant — all that matters is a disk image whose size matches the device's total number of blocks. That total differs between SMD and WD (Winchester/ST-506) disk images and between capacity classes.

Authoritative sizing tool: ndtool (the NDFS disk-image tool) creates correctly-sized images via --create <template>. Verified templates (from ndtool -h):

Template Device class Capacity Total pages (verified) Cross-check
floppy360 floppy 360 KB 154 matches ndtool -h
floppy12 floppy 1.2 MB 616 matches VSXK1.txt (616 pages); ⚠ ndtool -h annotation says "512" but the tool produces 616
smd75 SMD 75 MB 38400 matches BIGDISK0-K/L (38400 pages)
winchester74 WD / Winchester 74 MB 36360 —
custom any --pages N N —

Page counts above are verified by running ndtool --create <template> then ndtool -i (temp images, removed after). SMD ≠ WD: smd75 = 38400 pages vs winchester74 = 36360 pages — the total differs by controller class even at similar nominal capacity, so the image must be created with the template matching the real device.

To create and verify an image: 

ndtool --create smd75 --name PACK-ONE newdisk.ndfs
ndtool -i newdisk.ndfs        # confirm page count / sizes

MACM's own disk-type octal table (used at load time) is in 02-BOOTSTRAP-MACM.md §5 [DOC §3.4].

Verified data point: the golden PACK-ONE directory on a 75 MB pack reports Filesystem image size = 38400 pages (BIGDISK0-K.txt, BIGDISK0-L.txt).

Note: "pages" (file-system pages) is not the same unit as device "blocks" — keep the distinction explicit when deriving image size. (Relationship: TODO/verify.)

Device → directory mapping

The disk device chosen drives the CREATE-DIRECTORY / ENTER-DIRECTORY arguments (verified, System initialisation.txt):

CREATE-DIRECTORY PACK-ONE DISC-75MB-1 0
ENTER-DIRECTORY  PACK-ONE DISC-75MB-1 0
  • PACK-ONE — directory (volume) name
  • DISC-75MB-1 — device + unit
  • 0 — subunit

Device-type tokens seen across versions: DISC-75MB, DISC-38MB, D-75-1 (M HENT-MODE), ST-506/Winchester, SCSI.

K05 "D version" (SINTRAN-K05 archive, FLOPPY/readme.txt, verified):

"D version does not have support for ST-506/WINCHESTER. But it does have support for SCSI."

TODO

  • Confirm exact device tokens accepted per SINTRAN version.
  • Block counts / image sizes per SMD and WD device (see table).
  • Page↔block relationship.