r expires: you can use it for many other purposes,
such as synchronizing timers, or updating scanlines on the screen. More on
this later. The <CODE>PC</CODE> contains the memory address from which our
emulated CPU will read its next opcode. 
<P>
After initial values are assigned, we start the main loop:
<FONT COLOR=#000080>
<PRE>
for(;;)
{
</PRE>
</FONT>
Note that this loop can also be implemented as
<FONT COLOR=#000080>
<PRE>
while(CPUIsRunning)
{
</PRE>
</FONT>
where <CODE>CPUIsRunning</CODE> is a boolean