I wonder if there is/are reasons for Atmel to produce uC that have maximum Osc.Frequency of 20 MHz.
I have bought some 89C51 20PC and 52 20PC (the 20PC denoting Commercial 20 MHz maximmum oscillator frequency) and the 20 MHz Crystals, but realized then when using it in serial communication, it is difficult to set the baud rates (well i'm expieriencing it).
Is this a problem ? Or is there any solution to get the GOOD baud rates without changing the Crystal (It would be very desierable for me to achieve the fastest serial communication and shortest uC process time) ?

Everyone say that it is better to do baud rate setting with 24 MHZ crystall. But I have bought 20 MHZ uC.
Anyone have tried to overclocks uC ? I have planned to force it to run at 2 * 11.059 MHz = 22.118 MHZ if the crystal avaiable.
What are the effects of overclocking uC ?(temperature, stability, noise etc.)
Thank You
Alex