Howard,

 Personally, I make them outputs and leave them in the high
 state.  I think this is a carry over from TTL days and just
 didn't get changed in my mindset.  I really believe that it
 as a matter of personal opinion on which way to treat them.
 The thing in CMOS is don't let them go unterminated.  You
 must do something with them.  If left floating and not
 terminated in some way, they can toggle with adjacent pins
 and cause power consumption to go up, they can cause programs
 to go astray if they are read and not dealt with, and a whole
 list of other reasons that are too numerous to list here.
 Suffice it to say as long as you terminate unused ports in
 some way that makes sense to you and the application, and as
 long as they are dealt with in the program if need be, then
 it's just a matter of personal taste, and application
 functionality and possible future expansion, etc. that will
 determine which way to terminate them is best (better) for
 that particular application.  I know I've been a little long
 winded here, but I hope you understand what it is I'm trying
 to say. If there is anything here you have questions on, let
 me know and I'll try to calrify.

                                        Regards,

                                         Jim




>Does anyone have an pinion on what to do with unused ports?
>Make them outputs and leave floating, and set or clear?
>Make them inputs and pull up or pull down?
>And.... speaking of inputs, what do think is best, pull up and input as
>a clear, or pull down and input as a set?
>Opinions gratefully received.
>Regards Howard.
>