By doing this we don't need to call bios functions, we can just jsr
directly to the addresses. This does mean that everytime the bios
changes the bootloader has to change, but ideally all the bootloader
does is load the bios and then get remapped out of memory. Any important
drivers like file system can be loaded from the bootloader.
This also means that the runtime functions are located in the bios for
the bootloader, so the rom will have to stay mapped in until the kernel
is started, at which point it will have its own runtime and the rom and
bootloader are no longer needed.
Now that we are adding our own target we can compile our own toolchain
instead of using the stock one. This does mean that there isn't really a
purpose to using the alpine cc65 image though
Instead of using the bootsector to load a bootloader, just put the
bootloader in the ROM and call it a day. It looks for a file on the SD
card in the root directory named `kernel.bin` and loads it into memory.
This is not a perfect solution, as the kernel will grow larger and the
kernel load address will have to change. At this point I could add back
the bootloader, but that is for later.
Also the bootloader is just a copy of the kernel, so that can be trimmed
down a lot.
