>                       BUT.  I wrote my code to go into a windowed C554.
> All will fit properly, but I have a problem.  This part has only one
> bank of user RAM.  Upon interrupting, I might be in the upper page, and
> then my W save action will go zinging off into cyberspace.  Even if it
> makes it to the lower page, upon restoring STATUS, it will definitely
> read zeros when it looks in upper page.

The memory architecture on some of those things is--as you have observed--a
real pain.  It need not be a showstopper, however, as there are some work-
arounds.

Two that I have seen that may be applicable are:

[1] Use the top bit of PCLATH.  This will require 3 extra cycles on interrupt
    entry, and 3 on exit.

[2] Use something like this [nb: this uses up an extra stack level]

Intr:
        btfss   RP0
         goto   NotSet
        bcf     RP0
        call    IntMain
        bsf     RP0
        retfie
NotSet:
        call    IntMain
        bsf     RP0
        retfie

IntMain:
        movwf   WSave
        swapf   STATUS,w
        movwf   SSave
        ...
        swapf   WSave,f
        swapf   SSave,w
        movwf   STATUS
        swapf   WSave,w
        return          ; ** NOT RETFIE!

This is a bit clunky, but it should be workable.