However you would be unlikely to find a crystal around that works at speeds slower than a frequency on the order of 10's of kHz. Note that one such crystal frequency commonly found in the market is 32.786 kHz.

If you had an aim to run your processor at a much lower frequency than 32 khz then you could implement the circuit shown by Charles at http://www.8052.com/forum/read.phtml?id=69111 and connect the appropriate output to your microcontroller on the X1 (OSC1) pin.

There is another part called the CD4536 (datasheet here ... http://rocky.digikey.com/WebLib/Te...D4536B.pdf ) that may be interesting to look at as well. It is possible to connect a 32.768 kHz crystal to this part in a manner similar to the way shown in Charles' CD4060 circuit. The difference on this one is that you can use a simple 5 position switch to select which frequency output you want to use and the selected clock comes out a certain pin on the part.

Michael Karas