If you be meaning the missing pullup on RA4 on the 16F84 for instance, this
is
because you may wish to control a device that may have a 12V swing to it.
If a pull-up
to the 5V supply was there, you would have an unwanted configuration
wouldn't
you.

Some people think that this pin can also source more current, but I haven't
seen this
spec'd anywhere.

Craig

-----Original Message-----
From: Andre Abelian <andre@COMPUFIRE.COM>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Monday, June 22, 1998 3:38 PM
Subject: internal pull up


>
>Hi to all Engineers.
>
>I like to know why In meny circuitrys including
>microchip application notes internal pull ups are not used.
>Is there any reason for that or this is just up to the designer.
>
>
>Andre Abelian
>                                        thank you
>