SNIP
> >My question is: Can I use a 54RC with XT oscillator? Did someone
> >make it?
> >
>
>
> Parallax used 16C55RC with a 3.58MHz ceramic resonator in their PIC
> programmer. Don't know how successful it was. Seems like penny pinching
to me.

Sure you can do this.  The RC parts do not have the oscillator tested.  I
have seen products that have this configuration.  There is NO GUARANTEE of
operation at the temperature and voltage specifications.  I have been faced
with this decision in the past and in the best interest of the company, I
elected for XT parts.  It is not worth the risk of a poor reputation should
failures occur.

Craig R. Autio
cautio@equinox.shaysnet.com