Figure 2 shows the format
of a stack frame. </P>

<P><IMG SRC="Fig3.gif" ><BR>
<BR>
<B>Fig.2</B> Format of a stack frame </P>

<P>For example, the source code instruction </P>

<PRE>   i := i + 1
</PRE>

<P>is translated into the code </P>

<PRE>   LOAD 0,3  load value of i (at address 3 in current frame)
   LIT 1     load constant 1
   ADD
   STO 0,3   store result to i
</PRE>

<H3>Classes</H3>

<P>Figure 3 shows the primary classes of the compiler (an arrow from A to B
means that class A is used by class 