It's in all of the newer ('96-97 or greater) data sheets.  It was left
     off of the old ones inadvertantly and is still not in the 16F84 or
     16C84 data sheet.

     However, the picture of the RA4 pin in the data sheet has always
     correctly shown only a N-channel tr. on the pin in all data sheets.
     Note that this feature is on the 16C55X/6X/6XX/7X/7XX/8X/9XX but not
     on the 16C5X.

     As Dr. Strangelove said, "But the whole point is lost if you don't
     tell the world!"

     Rgds, Brian.


______________________________ Reply Separator _________________________________
Subject: Re: Open drain
Author:  John Payson <supercat@MCS.NET> at Internet_Exchange
Date:    4/16/97 8:54 PM


[re port pin RA4]
|     Yep, that's why its open drain.  Must limit to +14V and if driving a
|     relay, watch out for back EMF.

Is the +14 limit documented anyplace?  All of the PIC books I've seen
document the max on "any pin other than /Mclr" as Vdd.  Does Microchip
"officially" allow RA4 higher?