Update bootloader README and clean up makefile

code/boot/README.md

@@ -1,31 +1,35 @@
 # Boot Firmware for CHIBI PC-09
 
-TODO: Description of what the firmware does for the PC-09.
+This is the firmware for the CHIBI PC-09. In the future it will provide the
+CHIBI with initialization code, a UART driver, some self test features.
 
 ## Building the Firmware
 
-You will need GNU `make`, and [`asm6809`](https://www.6809.org.uk/asm6809) to
-build the firmware. Obtaining a working copy of `asm6809` could be difficult if
-you aren't on Debian, Ubuntu, or Windows as instructions for building it are not
-given on the `asm6809` website. Functional instructions for building from Git or
-tarball are given here:
+Building the firmware from source requires [LWTOOLS](http://www.lwtools.ca/) for
+building S-Records of the ROM, and `mot2bin` from
+[F9DASM](https://github.com/Arakula/f9dasm) for building binary images. A GNU
+Make makefile is provided for building on Linux.
+
+### Using the Makefile
+
+To generate an S-Record run:
 
 ```sh
-git clone https://www.6809.org.uk/git/asm6809.git
-cd asm6809
-./configure
-make
-sudo make install
+make boot.s19
 ```
 
-From there all you should have to do to generate a `boot.bin` is:
+To generate a binary run:
 
 ```sh
-git clone https://github.com/amberisvibin/chibi-pc09.git
-cd chibi-pc09/code/boot
 make
 ```
 
+The makefile also can clean up after itself:
+
+```sh
+make clean
+```
+
 ## Firmware Licensing
 
 This firmware like the rest of the CHIBI PC-09 is licensed under the MIT