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I know that the first and official wallet is bitcoin-qt. This wallet has code here: https://github.com/bitcoin/bitcoin
What was the first official miner software? I understand that bitcoin-qt never use as miner software. Where is official code of miner software?
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The first official mining software was Bitcoin Core (then known simply as Bitcoin, later bitcoin-qt), and it still serves as a reference mining implementation, making it the "official" miner. See its miner.cpp file, for example.
Bitcoin Core uses your CPU to mine. Mining eventually moved to GPUs and ASICs, so that mining on a CPU is practically pointless right now. In that sense, you should never use Bitcoin Core as mining software. But it still is mining software.
The original client was called just "Bitcoin" and used wxWidgets rather than QT. Starting with version 0.5 it was merged with Bitcoin-qt, but by then mining had already been disabled. – Meni Rosenfeld – 2014-10-13T16:47:25.357