>On Wed, Sep 17, 1997 at 04:19:31PM +0930, Mike Smith wrote:
> On 16 Sep 97 at 21:56, Pioneer Microsystems wrote:


 > 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


This works for me in a '554:


INTRTN      BCF             STATUS,IRP   ; Save the Page bit in IRP
                  BTFSC        STATUS,RP0  ; not a Microchip approved
scheme
                  BSF             STATUS,IRP    ;

          BCF             STATUS,RP0  ; guarantee page 0

          MOVWF       WSAVE            ; Save W
                  SWAPF       STATUS,W      ;

          MOVWF       SSAVE             ; Save Status


;            Balance of the interrupt service routine

;           Restore context and return from interrupt

                 SWAPF       SSAVE,W           ; Restore most of
STATUS
                    MOVWF       STATUS            ;

                    SWAPF       WSAVE,F           ; Restore W
                    SWAPF       WSAVE,W          ;

                    BTFSC       STATUS,IRP      ; Restore the page
pointer
                    BSF             STATUS,RP0    ;

                 RETFIE                                   ;