* Now that the BIOS is loaded we can start executing it!
The starting address the EE uses is 0xbfc00000 which maps
to KUSEG1. Since all KUSEG regions except KUSEG2 are mirrors
of each other we only need to translate the address to the
KUSEG appropriate.

* The functional differences between KUSEG0/1 are minimal and
very niche so I won't bother emulating them now. Address wise
we can notice that the only difference between addresses is the
most significant half byte. By using that byte as an index in
a mask table we can define an appropriate mask for each KUSEG
address. Idea taken from a very handy PSX document I discovered
last year [1]

[1] https://svkt.org/~simias/guide.pdf (43)

* The ps2tek documentation states the memory map clearly [1].
It seems to have a similar architecture with the PSX, where
the main memory map (KUSEG0) is mirrored in multiple regions
(KUSEG1/KUSEG2) with different access patterns for each region.
For now we don't have to emulate all of them, just the main
memory map.

* Allocate the entire 512MB memory into an array and make a convenient
struct to abstract memory range operations.

[1] https://psi-rockin.github.io/ps2tek/#memorymap