Hi Alok,

> it is error of (24000000-2396000) clock cycles every
> second

1 - 2396000 / 24000000 = 0.2%
= excellent accuracy for baud rates.


> it depends on how does a controller optimise about the
> crystal frequency, the division factor and drifts in
> crystal frequencies because of change in physical
> condition.

This is only important for timer applications (RTC).
For high accuracy software RTC please look at:
http://www.specs.de/~danni/ap.../index.htm


> but i am surprised that none of the crystal's
> frequencies
> available in commercial market actually match the exact
> requirement

Often baud rates up to only 9600 baud needed.
With using timer T2 any crystal above 10MHz can do it.
E.g. we use a 32MHz crystal, fine for up to 57.6 kbaud (2%).


Peter