
See the top level README file for more information on documentation
and how to run these programs.

This is a very simple bootloader.  Instead of the sd dance (see
top level README), this makes life a bit simpler and greatly reduces
physical wear and tear on the sd card socket.  Do the sd card dance one
more time with this kernel.img.  Get some sort of serial solution to
connect a dumb termial program with the ability to download raw/ascii
files.

bootloader01 was .hex based, this one is also .hex based but a
different way to parse it.  bootloader02 through bootloader06
expect binary files, a binary image of the memory starting at
address 0x8000.  I intend to release bootloader08 at the same time
and it will be .bin based but have the go feature.

This bootloader07 parses intel hex formatted files.  Look that up at
wikipedia, it is very simple and historically widely used for bare
metal embedded work.  (S record is another format like intel hex but
of course motorola had to have their own.  Intel hex and Motorola S-
record).  I felt like doing another state machine and honestly had
forgotten I did one before in bootloader01.  This bootloader does
not make any of the others obsolete, it was just a fun exercise.

The thing that annoyed me the most about my bootloader is that
I use minicom and minicom spawns a separate program to do the file
transfers, xmodem, ascii, kermit, etc, and there is a delay and
a loss of data when the spawned program exits and minicom returns.
The solution is that you hit the g key when you want the program
to start so you are basically back in the terminal at that point.

I normally do not deliver binaries.  In this case I have included all
of the build files so that you can at least get started without having
to build the bootloader.  Backup whatever kernel.img file you are using
and replace with the kernel.img file in this repo (on your sd card) to
use this program.  If on a Raspberry Pi 2 then use kernel7.img instead
of kernel.img.

blinker.hex is for older RPi boards the A and B whose activity led
is tied to GPIO16.  The A+, B+, and RPi2 use GPIO47, also on these
latter boards the power led is on GPIO35.  Last I checked they wouldnt
provide a schematic for these latter boards (so much for being "open")
so we have to just go on faith...
