 implement most of the code in
<CODE>WriteMemory()</CODE>, keeping <CODE>ReadMemory()</CODE> as short and
simple as possible. 
<P>
After the opcode is fetched, we decrease the CPU cycle counter by a
number of cycles required for this opcode:
<FONT COLOR=#000080><PRE>Counter-=Cycles[OpCode];</PRE></FONT>
The <CODE>Cycles[]</CODE> table should contain the number of CPU cycles
for each opcode. <B>Beware</B> that some opcodes (such as conditional
jumps or subroutine calls) may take different number of cycles de