How do OS installers works if there isn’t any OS that could manage applications in an empty computer?
In: Technology
A CPU is a machine for executing machine code instructions. You put machine code instructions at a location in memory, set the CPU’s instruction pointer to the starting point of those instructions, and let it run.
The OS, once installed, has to be on a piece of persistent storage like a hard drive. So it would have to be copied into RAM before the CPU could run it. Copying data into RAM from a hard drive is a *very* complicated task, relative to what a CPU knows how to do on its own. So instead, a little bit of code is built into your motherboard that knows how to
1. Find a storage device
2. Copy the first 512 bytes of that storage device into RAM at an architecture-defined address
3. Set the instruction pointer to that address
The true way to run software on your machine is therefore to put code in the first 512 bytes of a USB stick or something, plug it in, tell the BIOS to use that drive, and then let it boot. Usually the code in these 512 bytes just copies *more* code from the rest of the drive, and points the IP there.
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