Hi Keith (Keith Howell), in <34965DC5.EBE@arcam.co.uk> on Dec 16 you wrote:

> As a result, because the chip architects some sloppily thought putting two
>  different registers at the same
> logical address, all chip programmers are condemmed to thinking harder and
 more
>  carefully to compensate. There
> are work-arounds, but I'm not pleased at having to do this extra work.
>
> The words "Oh bugger" form in the mind.

The AVR architecture is quite nice on this, it has a PORTx register which
is the latch.  You can read back what you wrote to it for bit operations.
And it has PINx, which represents the actual voltage level on the pin.