Four meanings of 'this game doesn't work'
In a reprogrammable 161-in-1 system, a title might fail because its original cartridge uses banking/protection hardware the replacement does not implement. A converted or bootleg substitute might boot but differ from the retail game. A game image or menu entry might be wrong. Or the cartridge, CPLD build, contacts, supply or host MVS board might be at fault.
Those cases require different remedies. Calling all of them 'incompatible' obscures the source of the problem and risks needless hardware work. Our research therefore tracks mapper limitations, altered conversions, format errors and motherboard-specific or electrical faults separately.
A passing checksum is not a passing game
Neo Geo games have distinct content families: P for 68000 program, C for sprites, S for the fixed/text layer, M1 for the Z80 sound program, and V for sampled audio. Matching the expected hash of one transformed region tells us which bytes we produced, not whether every other region, bank-selection path and runtime feature behaves correctly.
Our tooling keeps independent region identities, source transformations and failure ledgers. It uses local legally held data for any direct comparison and can run synthetic tests without distributing commercial game content. A successful P transform can coexist with an unresolved S/FIX reduction or V/PCM2 issue.
Three documented failure patterns
| Symptom or finding | Likely classification | What would distinguish it |
|---|---|---|
| Menu works; selected title reaches crosshatch | ROM/build state, cart or host fault—not automatically game incompatibility | Clean CPLD synthesis, verified image, other slot and board |
| Title plays but FIX/text layers are wrong | Graphic banking or converted-image compromise | Trace late FIX bank/tile selections through gameplay |
| Original protected form needs unavailable cart logic | Mapper/protection architectural limitation | Compare actual board logic and documented source-model requirements |
| Intro runs but late game crashes | Possible runtime/protection or data-bank defect | Repeat long gameplay, transitions, reset and region variants |
A case from the evidence ledger: stale tool state
One documented community VTXCart report described a sequence where early menu positions booted while later positions failed or launched the wrong title. The reported explanation was stale Quartus-generated tables: removing synthesis working files and rebuilding restored the intended mapping.
That was a third-party account, not a lab reproduction at Atelier Rocky. Its value is methodological: a build artifact can imitate a game-compatibility failure. Before declaring that a particular game is impossible, verify that the programmed CPLD and flash actually contain the intended build.
Why original late-era games are difficult
Some later Neo Geo cartridges depend on dedicated logic such as SMA or NEO-PVC for more than static ROM rearrangement. NEO-PVC, for example, includes a mapped register/RAM area involved in bank selection and colour handling. A cartridge offering simpler fixed banks cannot reproduce that behaviour just by accepting a new title name.
Our VTXCart audit distinguishes original protected retail forms from converted forms designed to run on available mapping hardware. A playable conversion may be useful, but that does not make it byte-for-byte or behaviourally equivalent to the original game.
The testing ladder we now use
- Record exact motherboard, cartridge PCB revision, firmware/CPLD commit, image identity and test conditions.
- Establish source provenance and compare each relevant ROM region separately; distinguish original and converted assets.
- Rebuild tool-generated logic from a clean state and verify programming, not just source files.
- Try multiple menu positions, BIOS modes and known-good hardware where safely possible.
- Test attract mode, real play, special moves, later stages, audio, reset, continue and game-over.
- Classify the result as proven on the tested configuration, unresolved, converted-only or fundamentally missing a hardware feature.
What a credible compatibility table should say
A green check should identify the precise software layout and hardware setup on which it was observed. 'Runs on a converted VTX list' is a different statement from 'original retail cartridge logic is supported.' Similarly, a reported failure on one MV1F setup does not establish failure on every MVS motherboard.
We are researching the distinction rather than publishing unsupported broad compatibility promises. Atelier Rocky's Neo Geo accessories remain future workshop ideas, not qualified commercial products.
Sources and further reading
Original documentation and specialist references consulted for this article. Always check your model and revision.
Information only: no product compatibility test is being claimed. These workshop accessories are not yet for sale.