vis-platformnotes-doc

The canonical Tandy / Memorex VIS platform checklist, carried from one documentation pipeline to the next and added to by each.

→ vis-platform-notes.md

Each VIS title I document will produce two things: a repository about that disc, and whatever it taught me about the format. The second kind of finding does not belong to any one title, and keeping a copy of it in every pipeline is a recipe for three copies that disagree. This repository is the single copy. Pipelines link here rather than fork it.

Where this one starts, which is not where the others did

The machine is partly known and its discs are not. That is an unusual place to open a platform checklist from, and it is why this document uses three marks rather than one.

Three years of homebrew on this console — an OPL3 synthesizer, a media browser and a native Wolfenstein 3D port — produced a great many real measurements about the console: its timers, its audio hardware, its display path, its input, and a long list of things that do not work the way the SDK says. None of it came from opening a retail disc. It came from writing code, running it, and watching it fail.

Mark	Means
[N of 3]	Measured on retail pressings. Three are in hand; the denominator moves as more are opened.
[authoring]	Proven by writing code that runs on the machine. Real measurement, wrong direction — it says what the console does, not what a published disc contains. To date the "machine" has been MAME's VIS driver, not silicon; the console itself is genuinely scarce.
[unverified]	From the Tandy SDK documents, and not measured at all.

A mark is never promoted because nothing contradicted it. An [authoring] finding does not become [3 of 3] because it ought to hold on a retail disc.

The three-mark scheme is not bureaucracy. The [authoring] category has already been wrong twice in ways only running code could reveal, and both corrections are in the document in place, with the wrong version still visible: a PCM DAC this document recorded as absent and that turns out to sit at 0x220–0x22f behind raw DMA channel 7, and a display flag read as NOWAIT for a whole session that was STRETCH 2X the entire time.

What it covers

Section
1	What the machine is — an 80286 running Modular Windows in ROM, so a title is a Win16 NE application, not a boot image; and the two hard limits (tlaunch ignores AUTOEXEC, LoadLibrary raises "insert main disc")
2	CONTROL.TAT — the vendor block, 84 bytes byte-identical across three unrelated discs, naming the tool that wrote it (Maketat), its build version and its date, with the title field where the leftovers live
3	ISO 9660, and reading a disc that is really an uninstalled Windows install tree
4	Censusing the disc — including two independent dates per pressing, which no other platform here offers
5	The display path: nine documented DVA modes, one proven, zero measured on retail; GDI against DispDib; and the flag that was read wrong for a session
6	Audio: OPL3 at 0x388/0x389, the DAC this document said did not exist, and the PIT that runs at ≈596 kHz so every constant borrowed from PC arithmetic is off by two
7	The hand controller — virtual keys 0x70–0x79, no WM_KEYUP, and why HC.DLL in the import table detects a title that reads the controller
8	The executables: NE headers, and an import table that is a capability list, for free
9	Under 1 MB of DOS arena — the constraint every commercial title was also written under, and what it predicts about their discs
10	Baselines — three rows, CONTROL.TAT columns filled because they are measured, everything else waiting
11	Order of work — the machine half established, the disc half proposed
12	The hash lists, and the cross-disc result this platform already has

Discs it is drawn from

None documented yet. Three retail pressings are in hand and have given up their CONTROL.TAT (section 2) and nothing else. The full write-up for each will live in the family index: vis-gamelist-doc.

Disc	Year	Maketat	What is known
Atlas of U.S. Presidents	1992	1(12) 31-Aug-92	Applied Optical Media. Title field claims Ver. 1.0
Bible Lands, Bible Stories	1992	1(12) 31-Aug-92	Context/InterMedia. A retail pressing whose title field calls it a prototype demo
Fitness Partner	1992/93	1(13) 9-Oct-92	Computer Directions. Title field says V.90 — a pre-1.0 version number, shipped

The result this repository already has

The leading 84 bytes of CONTROL.TAT are byte-identical on all three discs:

Copyright (c) 1992 Tandy Corporation. All Rights Reserved.
md5 ed9bfc904220e409f04c0772f1797ff7   (first 84 bytes)

Three studios, three subjects, one block — written by Tandy's mastering tool rather than by anybody who made a title. This is the VIS's answer to the CD-i publisher's bumper and the Amiga CD .TM block, it is the platform's cheapest identity check, and it cost one afternoon of comparing three small files.

The same file also stamps which build of Maketat pressed the disc, and when — and two builds six weeks apart are already visible across three discs. That is a mastering-chain fingerprint of exactly the kind section 3 of the Amiga CD notes is built on: it dates the pressing process independently of whatever the title claims about itself.

And it has already produced a leftover, in the field nobody reviews: the retail Bible Lands pressing describes itself as Bible Prototype Demo, and the retail Fitness Partner calls itself version .90.

Contributing from a pipeline

When a title turns up something about the format rather than the title:

1. Add it to the relevant section here rather than to the title's repository.
2. Respect the three marks. [unverified] → [authoring] needs code that ran; [authoring] → [N of 3] needs retail discs. The two are not interchangeable and the whole value of this document is that it says which is which.
3. Move the denominator. When the fourth disc arrives, every [3 of 3] becomes [3 of 4] or [4 of 4] — re-derive the ones your disc exercises and re-declare the rest in place with a note. Two sessions of postponing a mark turn it into furniture.
4. If a finding contradicts what is written, correct the text and say so in place. This document already has two such corrections and both are more useful with the history attached than without.
5. Update the baseline table in section 10 and the order of work in section 11, and publish notes/sha1-all.txt for your disc (section 12).

State what is measured and what is inferred, and keep the measurements in the document. Half of what makes a disc interesting is the list of things that are measurably odd and not yet explained.