I said earlier: the data must be prepared. For example, shifted by nonce (4-byte) and some other operations. The nonce should be loaded as well (is now a part of data). A golden nonce in Bitcoin mining is a nonce which results in a hash value lower than the target. What happens if the target == 0xFFFF....FF? Right: any result will be returned.
There are several ways to generate keys. In some, you have to complete 100k SHA256 hashes (or 50k double hashes). This way allows to reduce the enumeration range, by the way.
Finally, which ASIC do you mean? There are many chips: https://en.bitcoin.it/wiki/List_of_Bitcoin_mining_ASICs
Only Bitmain has four actual chips right now. All chips are different, have different OCD paths, "some ASIC chip" does not exist.