On Sun, 27 Feb 2000 02:21:24 -0500, you wrote:

>What is the difference in using just a crystal on the pic or using it with
>the 2 capacitors?
>As usual, a quick look at the 200 page data sheets for the 16F876 didn't
>produce an obvious answer so I assume someone here knows.
>
>I have been running with just a bare 4MHz crystal on osc1/osc2 and no
>capacitors, and someone told me that's fine and capacitors would probably
>cause trouble if anything for me since they have to be properly calculated
>etc.  He said he is putting capacitors on his circuits though because his
>will be going outside and he wanted some stability.
>
>So how does one decide?
>
>Also what's the difference between crystal types?  I am using "general
>purpose microcontroller" parts but there's those other series or parallel or
>other specific types.  Again how would I know what to choose?
You should always use caps. There is a risk of unreliable operation,
or operation at the wrong frequency without them. It could be that
your PCB has enough stray capacitance to make it work. 
Check out Microchip App note AN588 for everything you ever wanted to
know about crystals, but don't be put off by all the detail - cap
values aren't usually too critical in most apps  -15 to 33 pf is
usually fine.