Vinod,

You may find the DS89C420 to be more restrictive than you initially thought. Consider this - in order to toggle a port pin HI then LOW, you would use SETB and CLR. Both instructions take two cycles each, not one.

You might want to give us more specific details on your application. For example if you need glitch-free PWM or square wave generation, I would seriously consider a Cygnal part. Most can run at 25MHz (1 clock per cycle) and some even run at 50 MHz and 100 MHz. The Cygnals have a built-in PCA which make it much easier to produce precise waveforms.

Chances are that the Cygnal board will even end up smaller and cheaper as well.

- Lee