= Simple CPU Simulator =

A project written by Michael Crenshaw <mcrenshaw10@gmail.com> to fulfill Honors
Petition requirements for CSIS 434-001, Spring 2016.

== Usage ==

CPU.py when run alone checks for a file named program.dat in the current working
directory. It then assembles that code, compiles it, and then runs it. It writes
output from the lexical analyser, assembler, and compiler to intuitively-named
output files, and it writes the CPU's register and memory data to cpu_output.txt
and prints it to the screen.

If no program.dat exists, a default program hard-coded in CPU.py will be 
executed.

== Language Definition ==

<program> -> <series>
<series> -> <statement> | <statement>; <series>
<statement> -> <assign statement> | <loop>
<assign statement> -> <variable> := <expression>
<definite loop> -> TO <expression> DO <segment> END
<segment> -> <assign statement> | <assign statement>; <segment>
<expression> -> <element> | <element> <math operator> <element>
<element> -> <constant> | <variable>
<constant> -> <digit> | <constant> <digit>
<variable> -> <letter> | <variable> <letter> | <variable> <digit>
<math operator> -> + | - | * | /
<digit> -> 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
<letter> -> a | b | c | d | e | f | g | h | i | j | k | l | m | n | o | p | q | 
            r | s | t | u | v | w | x | y | z

Two major limitations of this language are that it does not allow nested loops
and that it does not allow complex math operations (that is, they must occur one
at a time).