of things which you may want to do in this
<CODE>if()</CODE> statement:
<UL>
<LI>Check if end of screen is reached and generate VBlank interrupt if so
<LI>Check if end of scanline is reached and generate HBlank interrupt if so
<LI>Check for sprite collisions, generate interrupt if necessary
<LI>Update emulated hardware timers, generate interrupt if timer expires
<LI>Refresh a display scanline
<LI>Refresh the entire screen
<LI>Update sound
<LI>Read keyboard/joysticks state
<LI>etc.
</UL>
<P>
Carefully calcul