The Zork Anthology (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

Plain ISO 9660, volume ZORK_ANTHOLOGY, one session, one Mode 1 data track, 120295 blocks = 282,933,840 bytes of user data. DISK.ID reads “The Zork Anthology / 1.0 / ZORK”. Not a hybrid: there is no HFS side, and modern macOS mounts it directly. 94 files in three directories (root, DEMOS, MECH2); see zork-anthology-1994.ls.txt.

Redump has two pressings of this disc: disc 82144 (120295 sectors, tagged “Original, Special Edition”) matches this copy’s block count exactly; disc 80023 is a different mastering (120445 sectors, tagged “Version 1.0”).

Structure: an installer disc, and mostly not the anthology

The surprise is proportions: the six classic games this disc carries occupy 1.3 MB of a 246 MB disc.

ZORKANTH.RED (1,289,064 bytes) holds the entire classic anthology - Zork I, II, III, Zork Zero, Beyond Zork, and the box’s bonus game Planetfall - as an Activision installer archive (magic bytes 52 52 01 29, “RR”). The DOS INSTALL.EXE unpacks it; the files do not exist loose on the disc.
Most of the disc is Return to Zork demo/full data: RTZ.PRJ (47 MB), RTZCD.PRJ (43 MB), and dozens of .MMV/.PMV/.LMV movie files at root, plus RTZCD.RED/RTZCDDRV.RED installer archives.
Demos of four products (per DEMOS/READ.ME, dated 1994-09-12): Simon the Sorcerer CD-ROM (SIMON.GME, SIMON.VOC at 34 MB), Return to Zork, MechWarrior 2: The Clans (MECH2/), and Planetfall: Floyd Strikes Back (PLANETF.IBM, 7.6 MB).

Inside ZORKANTH.RED

The .RED container turned out to be simple enough to read without running the installer. It is a bare concatenation of member records, each one self-contained (measured on this file; the whole archive walks cleanly as 27 records with no global header or directory):

Offset	Size	Field
+0	4	Magic `52 52 01 29` (“RR”)
+4	4	DOS packed timestamp (time in the low word, date in the high word), little-endian like all fields
+8	4	Compressed size
+12	4	Uncompressed size
+16	2	`FF FF` on every compressed member; on stored members it repeats the CRC at +18
+18	2	CRC-16 of the uncompressed data
+20	2	Zero
+22	2	1
+24	2	Method: 1 = stored, 11 = compressed
+26	13	Filename, 8.3 plus NUL padding
+39	2	Unidentified (varies per member)
+41	comp	Payload

The CRC is CRC-16/CCITT-FALSE (polynomial 0x1021, init 0xFFFF, non-reflected, no final XOR), determined by brute-forcing the parameters against the stored members, whose payloads are readable in place. The method-11 compression itself has not been identified (it is not PKWARE DCL), but it does not need to be: the recorded uncompressed size and CRC-16 identify every member against known files.

All 27 members: Z1.COM, Z2.COM, Z3.COM, PF.COM, BZORK.EXE, ZORK1.DAT, ZORK2.DAT, ZORK3.DAT, PLANETFA.DAT, BEYONDZO.DAT, ZORKZERO.EXE, ZORK0.EG1, ZORK0.CG1, ZORK0.ZIP, ZORK0.BAT, NNANSI.COM, ZORK1.BAT, ZORK2.BAT, ZORK3.BAT, PLANETF.BAT, six .ICO files, and a ZORK.GRP Program Manager group. The internal timestamps tell the disc’s build story: game payloads April-May 1992, NNANSI.COM January 1993, and the Windows dressing (icons, batch files, ZORK.GRP) August 1994. Even ZORK0.BAT is the 1992 LTOI file, stored with its 1992-05-11 timestamp.

Every game file’s size and CRC-16 match the byte-identical files on the 1992 LTOI CD and (via the shared lineage) Masterpieces and the 1997 Legacy Collection disc; the per-title table is in versions.md. This closes the loop on the shared-masters chain: the same 1992 files ship unmodified on all four products, 1992 through 1997.

Findings

“Planetfall: Floyd Strikes Back” is the demo’s 1994 title. The cancelled Planetfall sequel is usually referred to as Planetfall: The Search for Floyd (the title associated with the promotional planetfall.avi on the 1996 Masterpieces disc - see that disc’s notes). This disc’s READ.ME uses “Floyd Strikes Back” two years earlier, and ships a 7.6 MB PLANETF.IBM demo of it. The two discs bracket the project’s public naming history.
The READ.ME also dates Simon the Sorcerer’s CD-ROM release as “available … in 1995” and notes Return to Zork was already out on Mac CD-ROM.
.RED is Activision’s in-house installer archive format of this era (INSTALL.EXE/INSTALL.DAT/ITXT.* framework, “RR” magic). DRIVERS.RED and the RTZ .RED files use the same container.

Open items for this disc

Identify the .RED method-11 compression, so members can actually be extracted rather than just verified. Until then, INSTALL.EXE under DOSBox remains the way to unpack.

Resolved 2026-09-02: the game builds inside ZORKANTH.RED are enumerated and matched against the other discs via the container’s own size and CRC-16 records; see the section above and versions.md.

Resolved 2026-08-29: Redump verification. The full dump hashes byte-identical to redump.org disc 82144; see checksums.txt.