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A Quest For the Perfect SNES Emulator
An anonymous reader sends this excerpt from the Opposable Thumbs blog:
"It doesn't take much raw power to play Nintendo or SNES games on a modern PC; emulators could do it in the 1990s with a mere 25MHz of processing power. But emulating those old consoles accurately — well, that's another challenge entirely; accurate emulators may need up to 3GHz of power to faithfully recreate aging tech. ... As an example, compare the spinning triforce animation from the opening to Legend of Zelda on the ZSNES and bsnes emulators. On the former, the triforces will complete their rotations far too soon as a result of the CPU running well over 40 percent faster than a real SNES. These are little details, but if you have an eye for accuracy, they can be maddening. ... The primary demands of an emulator are the amount of times per second one processor must synchronize with another. An emulator is an inherently serial process. Attempting to rely on today's multi-core processors leads to all kinds of timing problems. Take the analogy of an assembly line: one person unloads the boxes, another person scans them, another opens them, another starts putting the item together, etc. Synchronization is the equivalent of stalling out and clearing the entire assembly line, then starting over on a new product. It's an incredible hit to throughput. It completely negates the benefits of pipelining and out-of-order execution. The more you have to synchronize, the faster your assembly line has to move to keep up."
You seem to be missing the point. The triforce spinning was probably a bad example, since it's not that important. The problems with inaccurate emulators range from annoying visual glitches, to crashes, to actually making a game unbeatable. Star Ocean, for example, will sometimes crash in zsnes, but I haven't experienced that in bsnes. The battles run at double speed, much like the triforce in LTTP. Playing Yoshi's Island in zsnes, any level with those giant fuzzballs will tick every time you move. It's nauseating to get through. In zsnes, Super Mario RPG battles will sometimes de-sync to the point that the music and animations will continue, but your input will no longer work and you have to reset the game.
In Speedy Gonzales - Los Gatos Bandidos, if you're playing with zsnes, you can't even beat the game, because it doesn't emulate everything necessary to do so. In Sink or Swim, the room fills with water, and you need to swim above it. But because of timing and speed issues, the room fills up much too fast and you will drown instantly.
You can read about some of these issues, and many more, here: http://byuu.org/bsnes/accuracy