Sebasti‡n Dols wrote:

> Can I assume that if I set the portb internal pullups via code, and I
> drive any portb pin with a 'below-5v-but-above-2v' signal, the pullup
> will 'raise' the signal to 'full-5V', and this will improve my signal
> adquisition?

  This could almost be true!  "Good old" TTL defined a logic "1" as
2.5V, so the totem-pole output did a good job of pulling a "1" to 2.5 or
3.5V, but didn't manage to pull it much higher.

  If you wanted to interface this to CMOS where the logic *threshold*
was in fact 2.5V, it wasn't so reliable and could be a little slow.  The
two solutions were to use 74HC logic where the input thresholds were
distorted to match TTL, or to pull up all TTL outputs to 5V with a
suitable resistor, which the TTL totem-pole (OR open collector) could
readily pull low.

  This is of not so much relevance to the PIC pull-ups which equate to
something like 50 or 100k, while the proper speed-up/ pullup for TTL
was more like 4.7k.
-- 
  Cheers,
        Paul B.