In article <346ac599.290867@smtp.netcomuk.co.uk>, Mike Harrison
<wwl@NETCOMUK.CO.UK> writes
>>(1)   Is it possible to operate  2  PIC16C84's  on the same  pcb from one
>>crystal ? (XT mode). The data sheet shows how to use an external clock input
>>but I am uncertain how to obtain this clock from the other PIC without
>>loading the  oscillator circuit.
>Yes - connect oscout on the crystal to oscin on the secons PIC. Keep
>track as short as poss. Adding a K or so series resistance may be
>useful to reduce loading, and you may need to reduce the cap on oscout
>to compensate for the extra track length and Cin of the second PIC

Or you could use one of the dedicated crystal oscillator chips such as
the Harris HA7210. Makes things much easier, if your budget can stand it
(about UKP 1 each).

Karel
--
     ++++++++++++++++++ KH Design & Development ++++++++++++++++++
     Electrochemical Corrosion Measurement and Control Consultancy
                   http://www.khdesign.demon.co.uk/