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Yes. As far as I know all the ASICs out there will only do SHA256 (though some might be even more restricted to only work with BTC). Some hash algorithms would be prohibitively difficult to put into an ASIC. There might be some other algorithms that could go into an ASIC, but that are used on coins that just aren't worth the development effort to do so.

Whatever the reason may be, it puts everyone on much more "even footting" when it comes to mining.

Asic can do scrypt, and some can do x11 too.

Yes Some asic and gridseed miner's do both. This is more for bitcoin, litecoin and Ethereum mainly. If you use EOBOT https://www.eobot.com/user/822288 and tie your miners in than you can mine multiple algorythems providing you use your miners to gain cloud mining power. This is also a great way to get more mining power for a low budget