Return to Zork CD-ROM v1.1 (1994) - findings

Established against a physical pressing read on an Apple Silicon Mac with a Pioneer BD-RW BDR-XS07U. The general method is in docs/imaging.md; this file holds what is specific to this disc.

Identity

Mixed-mode CD: one Mode 1 data track (volume RTZ-CD, 81843 sectors) followed by 25 Red Book audio tracks, 191601 sectors in all. DISK.ID reads “Return to Zork CD-ROM / 1.1 / Disk #1”, dated 1993-12-12; the READ.ME is dated 7 December 1993 and the disc root 1994-02-07. 169 files; see return-to-zork-1994.ls.txt.

Return to Zork exists in at least a dozen Redump-cataloged pressings (versions 1.00, 1.1 and 1.2, an OEM bundle, Megapak, Special Edition, FM Towns, and console ports). This copy’s sector count matches redump.org disc 80660 exactly - version 1.1, tagged “Rerelease”, write offset -22 - while two other v1.1 entries (126092 and the OEM bundle 33185) are three sectors shorter.

The pressing is Redump-verified, all 26 tracks. A full linear raw dump made 2026-08-29, split at Redump’s boundaries and corrected by 645 samples, hashes byte-identical to disc 80660 on every track; see checksums.txt. Two things had to be right for that to work, both learned on this disc: the correction is the combined offset (the drive’s +667 read offset plus the disc’s -22 write offset), and only track 2 carries a 150-sector pregap - the pause required after a data track - while the audio tracks that follow are gapless, so each later track’s file begins exactly at its TOC start.

Structure

• The 1993 Return to Zork build: RTZCD.PRJ (43,016,792 bytes, 1993-09-15) and 84 .PMV movie files, identical in size and date to the copies on the 1997 Zork Legacy Collection disc. The 25 audio tracks are the game’s CD audio.
• The v1.1 installer: INSTALL.EXE/INSTALL.DAT, RTZCD.RED (276,177 bytes, 1994-01-31) and RTZCDDRV.RED (111,013 bytes, 1994-02-06).
• Three demos, per the README: Simon the Sorcerer (SIMON/, 63 files - a playable demo run through RUNVGA GDEMO), MechWarrior II: The Clans (MECH2/, an intro movie), and Richard Scarry’s Best Neighborhood Disc Ever (SCARRY/, BEST.EXE with a BESTDEMO.PRJ and four movies). The README promises MechWarrior II “early in 1994” - it shipped in 1995 - and the two Richard Scarry titles for IBM and Macintosh CD-ROM in early 1994.

Gaps, post-gap and padding

Measured on the raw dump (2026-08-29):

• The data track is padded by a minute, and the pad is mastering slack. The ISO volume declares 77,268 sectors, but the data track runs to 81,843: the last 4,575 sectors (9.4 MB, 61 seconds) are structured empty Mode 1 sectors - sync, headers, EDC and ECC present, user data all zero. The Yellow Book calls for about two seconds of such post-gap before a mode change; this is thirty times that. Comparing across Redump’s Return to Zork family (2026-09-03) dissolves the mystery: the other v1.1 pressing (disc 126092, a different KAO glass master - ring X39220-1 against this disc’s CD06129-04) carries the same version and PVD and byte-identical audio track lengths, but pads to 81,840 - three sectors less. Same content, different master, different pad; and the family’s other masterings (Original 74,092; v1.2 at 81,028 and 71,158 data sectors) show the data-track length floating freely against the filesystem in every generation. The oversized pad is inert premaster slack whose exact length is set per glass master, not a revision artifact, not protection, and not recoverable intent. (The 1997 pressing’s mastering used exactly the canonical 152.)
• The v1.1 filesystem keeps the original’s birth date. Redump’s PVD capture shows this disc and the Original pressing (disc 112221) share the exact creation timestamp 1993-07-22 21:04:19 -08:00, though the Original’s data track is far smaller (74,092 sectors): the v1.1 volume was rebuilt from the original mastering project with its creation date carried over, while the content grew around it.
• The pregap before track 2 is 150 sectors of digital silence, all zero bytes. In an uncorrected dump its tail holds the first 2,580 bytes of track 2’s audio, pulled back by the drive’s read offset; the correction restores them.
• No pregaps between audio tracks. The silence between songs is inside the audio instead: the last 75 sectors (one second) of track 2 are zero and track 3 sounds from its first sector. The 1997 pressing does the opposite, with a 150-sector zero pregap before every track.

Compared with the 1997 Zork Legacy Collection pressing

The same disc, revised twice over. Against the 1997 disc:

• The game itself is unchanged. 92 of the 97 filenames the two data volumes share are identical in size and date - every movie and the 43 MB .PRJ among them.
• The install set was revised. The five differing files are DISK.ID (v1.1 -> v1.2), READ.ME, INSTALL.DAT, RTZCD.RED (276,177 -> 276,584 bytes) and RTZCDDRV.RED (111,013 -> 104,708), all redated September 1994. With the 1994 Zork Anthology disc’s much smaller RTZCD.RED (130,683 bytes, a demo install set), that makes three distinct Return to Zork .RED builds across three discs.
• The demos were swapped. This disc’s Simon/MechWarrior II/Richard Scarry demos are gone from the 1997 disc, replaced by the anthology, the InstallShield Windows front end, and the PDF documentation - which is where the 1997 data track’s extra 12,739 sectors go.
• The audio was re-cut. This disc’s audio is gapless after track 2; the 1997 disc inserts a 2-second (150-sector) pregap before every audio track, and each track’s content is also 154 sectors (2.05 seconds) longer, the last track’s 304. The two masterings also differ in write offset: -22 here, 0 on the 1997 disc.

Open items for this disc

None.

Resolved 2026-09-03: the 61-second post-gap explained by cross-pressing comparison; see above.

Resolved 2026-08-29: Redump verification, all 26 tracks; see above.