\chapter{Introduction}
This is an attempt to distill what I know about how computers work into some kind of emulator / simulator. I'm curious to see if what I know at the moment is enough to allow me to emulate a general purpose computer. It turns out that it take quite a different skillset compared to writing web applications or desktop applications. But I realize that, while I understand the concepts that underpin what I do day to day, I don't have an intuitive understanding of the hardware. This has become painfully evident pretty much immediately after I started this project. An ISA should be simple, add, subtract, copy, etc., but the you have to consider the state the processor will be in after each instruction. 
\section{Registers}
Thirty-two general purpose registers are available for program code to use however it wishes. The base name for the general purpose registers is \quotes{r} follows by an unpadded number, such as \quotes{r28}. These numbers do not follow a zero-based index scheme, \quotes{r29} is the twenty-ninth register. Using the base name implies full width, a \quotes{word}, when reading or writing from or to the register respectively. In addition to the general purpose registers there is also a base pointer (bp), stack pointer (sp) and an instruction pointer (ip). The base pointer and the stack pointer may be set directly using the \hyperref[sec:mov]{mov} instruction, which allows the programmer to set up a stack frame. The instruction pointer can only be set with a branching operation like \hyperref[sec:jmp]{jmp} or a call to a subroutine with the \hyperref[sec:call]{call} instruction.

\begin{description}
	\item In summary, the available registers are as follows:
	\item[General Purpose] Thirty-two general purpose registers that are the width of a \textit{word} and numbered \quotes{r1} through \quotes{r32}
	\item[Base Pointer (bp)] Points to the call location when a function call is made
	\item[Stack Pointer (sp)] points to the end of the last argument after a function call is executed, which may be the return address of the stack
	\item[Instruction Pointer (ip)] Points to the next instruction to execute and advanced by the width of an instruction. Set by jump or call instructions to the location specified by the instruction.
\end{description}

\section{Memory}