Ok, I got it wrong at the first sight.
It means that a 20MHz clock osc PIC can count up to 11Mps
without the use of prescaler, with single pulse counting,
or 195kps pulse counting with the prescaler (50MHz/256),
but losing 8 bits resolution.  The tip to multiplex the
input and then use another PIC pin to put pulses to the
prescaler until it overflows gets back the lower 8 bits.
Thanks for you all.
--------------------------------------------------------
Wagner Lipnharski - UST Research Inc. - Orlando, Florida
Forum and microcontroller web site:   http:/www.ustr.net
Microcontrollers Survey:  http://www.ustr.net/tellme.htm