SNK's Neo-Geo AES (Advanced Entertainment System) is a 16-bit console which still has games released for it today. As well as being a home console, the same hardware is used in the Neo-Geo MVS (Multi-Video System) Arcade machines. This means that the home system receives perfect translations of the arcade games - in fact, the cartridges contain both home and arcade code.
The Neo-Geo is considered by many to be the epitome of 1990s consoles - it was the system that spawned many classic series, such as The King of Fighters, Fatal Fury, Art of Fighting, (and many other fighting games), it featured many simply superb arcade games (try 2-player Windjammers for a while - more fun than you'd think of a Pong-like game), and the seminal blast-the-living-daylights-out-of-anything-that-moves-'em up, Metal Slug and its sequels.
The home console does suffer from the fact that the games are, and always have been, ludicrously expensive upon launch, with the rarer titles escalating into stupid figures. For collectors this is a godsend but the casual gamer may be put off. Thankfully, the arcade versions of the most expensive home games are considerably cheaper, and can often be played on an AES with the use of a converter.
CPU: A 16-bit Motorola 68000 running at 12Mhz, and an 8-bit Zilog-80A at 4Mhz. (Note: This does not mean it is a 24-bit machine)
RAM: 64kb Internal Memory, 68kb Video Memory, 2kb Z80 Memory
Maximum on-screen colours: 4,096
Maximum on-screen sprites: 380
Maximum amount of game planes: 3
Sprite size: Minimum 1x2, maximum 16x512
Sound Channels: 4 FM synthesis, 7 Digital Internal, 3 PSG, 1 noise
Joystick: Comes in two flavours. The old-style controllers are large, rather unweildy things, similar to arcade joysticks. It has the stick, start and select buttons, and four main buttons (A, B, C and D). The second style is smaller, and was brought out with the Neo-Geo CD, although is compatible with the cartridge-based original system. It has the same buttons.
Joypad: Frustrating if playing a fighting game, just as it is on any platform. However, a nice controller for everything else. If you're into the fighters, though, stick with the stick.
Memory Card: For saving game progress, the memory card was released. It could be used on both the home and arcade machines. Today, one can use any memory card with 68-pins and is JEIDA spec ver.3 or higher.
The games are still being produced, SNK having been snapped up by Playmore (now SNK-Playmore), their website being www.snkplaymore.co.jp .
The definitive online resource for the Neo-Geo has to be www.neo-geo.com, and its sister site the NeoStore. Run by Shawn, they are both excellent and highly recommended.