Added README and LICENSE file

Renamed gpl.txt to LICENSE and added README.md.

Signed-off-by: Collin J. Doering <collin.doering@rekahsoft.ca>

README.md

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+# Implementation of Hack computer architecture in VHDL
+
+## Features
+
+* Follows a similar structure to the implementation describe by the nand to tetris book
+* 
+
+## Tools
+
+The creation of this software was made possible by the following open source tools and
+libraries, and most notably, *Noam Nisan*, and *Shimon Schocken* who created the *Nand to
+tetris* course and accompanying book "The Elements of Computing Systems, Building a Modern
+Computer from First Principe's".
+
+* [Gnu Emacs][], because there is no place like home; and no greater editor!
+* [GHDL][], for VHDL compilation/simulation.
+
+## License
+
+This project is licensed under the [GPLv3][]. Please see the LICENSE file for full details.
+
+## Building
+
+    $ cd src
+    $ ghdl -i --workdir=work *.vhdl
+    $ ghdl -m --workdir=work <testbench> # simulate test bench of your choosing (eg. cpu_tb)
+
+## Issues
+
+Currently the chips called ROM, Screen, Keyboard, Memory and Computer in the *Nand to Tetris*
+book are not implemented. The ROM chip is simply a RAM16k chip with no write capability (the
+interface doesn't require a load bit). Computer and Memory are simply compositions of chips,
+leaving the hard work left to implementing the screen and keyboard. I aim to complete this
+via vga for the screen and PS2 for the keyboard, though I'm still in the process of research.
+
+[Gnu Emacs]: http://www.gnu.org/software/emacs/
+[GPLv3]: https://www.gnu.org/licenses/gpl.html
+[GHDL]: http://ghdl.free.fr/