> As an aside, why use the 16F84 at all?

Simple, really.  If you have 16F84 code and you aren't terribly familiar
with PICs it can be monstrously difficult to port.  Most of the 84 code
out there is absolute and horribly written.

The 84 is a great learning part because it avoids a number of
complications of all the other PICs, allowing the learner to bite off a
smaller piece initially. All of the GPRs show up in all banks so no data
mysteriously disappearing, and none of the I/O pins do weird things like
they do on every other PIC. (Sure, they're not weird when you are familiar
with them, but having I/O pins simply not work because you have given the
magic incantation can be very distressing.)

> It is expensive, old, and doesn't really have any peripherals.
> There are much better and cheaper PICs out there like the
> 16F628A as one example. Use the product search on Microchip's
> site and you'll see what I mean.

This, however, is also true.  The 84A is horribly expensive for what you
get.  Even the 628A is a little aged.  Many 16F84 projects don't rely on
EEPROM, which can make the 716 a really nice choice for the hobbyist
because of it's low price.  At the other extreme, the 88 has more of
everything and in hobbyist quantities, barely more expensive than the
628A.

But if the OP is a relatively new PIC user, the 84A is understandable. 
PICs can be pretty intimidating at first.  Better to spend a few bucsk
extra to get something warm and cuddly.

--McD


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