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SNK Neo-Geo AES

The Advanced Entertainment System: the home version of the Neo-Geo (1990), twin to the arcade Neo-Geo MVS. Same code, same hardware — but cartridges with a different pinout and a "luxury" aura (launched very expensive). No suicide, native RGB.

SNK Neo-Geo AES board
SNK Neo-Geo AES board. Photo: Evan-Amos, public domain.

Identification

Field Value
Manufacturer SNK
Release 1990 (JP), 1991 (NA)
Generation 4th (16-bit)
Media AES cartridge (pinout ≠ MVS)
Native video output RGB (+ composite / S-Video)
Region JP / US / EU

Architecture

Identical to the MVS: Motorola 68000 @ 12 MHz + Z80 @ 4 MHz, YM2610 sound, 320×224. MVS and AES run the same machine code. → Details: Neo-Geo MVS § Architecture.

AES vs MVS

  • AES = home console (smaller cartridges, its own pinout).
  • MVS = arcade (multi-slot, large cartridges).
  • Same games, same code; the cartridge pinout differs deliberately (market segmentation) → hence the MVS↔AES conversion adapters.
  • Some games have MVS/AES differences (endings, texts) that the UniBIOS lets you toggle.

Video outputs & region

  • Native RGB (SCART cable) — excellent picture.
  • Region (JP/US/EU): a few game differences; UniBIOS = region-free.

Source

From ConsoleMods (CC-BY-SA). Soldering: 🟢 none · 🟡 · 🟠 · 🔴.

Universe BIOS (UniBIOS) — THE AES de-zoning

  • Replace the BIOS chip with a UniBIOS (Razoola, a pre-flashed EEPROM or flash your own) → change the region (JP/US/EU) and the Arcade(MVS)/Console(AES) mode at boot, + cheats, test mode, hiscore save (with a memory card), soft reset. The stock BIOS is marked "531024".
  • ⚠️ All AES have a soldered BIOS (no socket) → two methods, exact points below.
Install UniBIOS on AES (soldered BIOS) — exact points (transcribed from ConsoleMods, CC-BY-SA)

"Piggyback" method (stack UniBIOS on the original BIOS) — materials: 1× 15 kΩ 1/4 W resistor + wire (optional: a 40-pin DIP socket for future updates).

  1. Find the BIOS chip (marked 531024). Find pin 2 (2nd pin counter-clockwise from the half-circle notch).
  2. Lift/cut pin 2 of the original BIOS (close to the board) and bend it parallel to the board.
  3. Bend the UniBIOS pin 2 the same way; place UniBIOS on top of the original BIOS, pins aligned, the two pin 2s must NOT touch.
  4. Solder all pins of both chips together except pin 2 (don't bridge neighbours).
  5. 15 kΩ resistor between pin 2 of the original BIOS and pin 40 (1st pin clockwise from the notch).
  6. Wire from UniBIOS pin 2 to pin 20 (common to both chips).
  7. Power on with no game → blue screen = install OK.

"Direct replacement" method: desolder the original BIOS (531024) and solder the UniBIOS in its place (ideally on a 40-pin DIP socket for updates). Settings are remembered with a memory card on AES. → Neo-Geo MVS § UniBIOS.

Play your library

  • NeoSD (Terraonion) — a flash cartridge holding the whole library on SD, plug-and-play 🟢.
  • MVS → AES conversion: play MVS carts on an AES via an adapter (different pinout).

Video & reliability

  • Native RGB: superb stock; an optional RGB Bypass Mod cleans the signal further on some boards.
  • Backup battery (internal memory) → Battery Replacement; recap (cap kit) per condition. (No "suicide" or accounting battery like on the MVS.)

Common faults

Symptom Likely cause Lead
Cartridge not read / crash Cartridge connector oxidation Contact cleaning
Lost save (game) Flat cartridge battery Replace the battery in the cartridge
No image Power, customs, multi-out Diagnosis
Settings/diagnostics — UniBIOS (test menu)

(No "suicide" or bookkeeping battery like on the MVS.)

Photos / assets

(To add: AES console, AES vs MVS cartridge, internal board.)

Advanced repair

Recap + cartridge slot contacts (No. 1 cause); UniBIOS handy for diagnosis. Methods: Recap · PCB fault-finding · Traces & vias.

Sources & attribution

Image:

Review & corrections

How this space is used

Spotted a wrong value, an outdated procedure, a chip reference that does not match your board? Say so here, with what you observed (model, board revision, serial number, measurement). Every report is cross-checked against a source before anything changes — an unverifiable correction is published as “reported by …, not cross-checked” rather than silently applied.

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