For example: A motherboard getting data to play a game for a console or a computer knowing how to be a computer. How do these things get programed into the motherboard when it’s a blank slate after the motherboard has been created when physically is just material? I hope that makes sense.
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Two ways to do that. 1. Program flash storage before soldering it to the main board. 2. Program via JTAG. JTAG allows to connect an external computer to the board, put the CPU into standby mode before it executes a single instruction, and talk to other components like flash storage or RAM on the board. The flash storage must have a JTAG TAP controller integrated into it to understand JTAG protocol. The protocol was deliberately made very simple to implement in hardware only. JTAG TAP controller does not require any software. It’s just a few hundred logic gates. Once flash storage with an integrated JTAG TAP controller is manufactured it understands JTAG protocol.
Next time the board is powered on the CPU reads the instructions from the flash storage.
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