The boot sequence

In simpler times, some years ago, it was only necessary to place the bootloader in non-volatile memory at the reset vector of the processor. NOR flash memory was common at that time and, since it can be mapped directly into the address space, it was the ideal method of storage. The following diagram shows such a configuration, with the reset vector at 0xfffffffc at the top end of an area of flash memory. The bootloader is linked so that there is a jump instruction at that location that points to the start of the bootloader code:

The boot sequence

Boot in the old days

From that point, it can initialize the memory controller so that the main memory, ...

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