> Page_1
> Bank_1
> call subr_1
>
> And have the termination of subr_1  looking like :-
>
> org    0x0200     ;Subroutines must go in lower half of PAGE 0
>
> subr_1 <.. Do an LCD display ..>
>              Page_0            ;And return to where we were in Page_0
>              Bank_0
>              retlw    0x00

> > org  0x00     ;PAGE 0, lower half
> >
> > org 0x0100    ;PAGE 0, upper half
>
> Pages are 2K in size, which takes 11 address bits.  100h is only 256 words
> into page 0.  Half way thru page 0 would be 400h.
>
> > Page_1
> > Bank_1
> > call subr_1
> >
> > And have the termination of subr_1  looking like :-
> >
> > org    0x0200     ;Subroutines must go in lower half of PAGE 0
> >
> > subr_1 <.. Do an LCD display ..>
> >              Page_0            ;And return to where we were in Page_0
> >              Bank_0
> >              retlw    0x00
>
> I don't know what page_0 or bank_0 do, but you don't need to set PCLATH
> before a RETURN.  The full 13 bit address is stored on the stack.  PCLATH is
> not used in performing a RETURN.
>
> >
> > org    0x0300     ;Upper half of PAGE_0
> >                   ;We can set up a goto instruc to call subroutines
> > from here
> > ;******************************************************
> >
> > 'Cause it loses track of where it is. Err .. so how would you call a
> > Page_1 (lower half) routine from a Page_0 (upper half) main programme?
>
> You seem rather confused about program memory paging.  Re-read the data
> sheet carefully and check the PIClist archives.  This issue seems to come up
> every week or so.
>
> In my opinion the short answer is to never manually set pages or try to
> allocate particular routines to pages.  Let the linker stick the routines
> where it pleases and use PAGESEL.  Take a look at my GCALL macro in
> STD.INS.ASPIC at http://www.embedinc.com/pic.
>
> ********************************************************************
> Olin Lathrop, embedded systems consultant in Littleton Massachusetts
> (978) 742-9014, .....olinKILLspam@spam@embedinc.com, http://www.embedinc.com
>
> --
> http://www.piclist.com hint: The PICList is archived three different
> ways.  See http://www.piclist.com/#archives for details.

>
> Use PCLATH ops
>
>         movlw   high PAGE1SUBADDRESS    ;get high byte address
>         movwf   PCLATH                  ;setup page numer, (anywhere)
>         call    low PAGE1SUBADDRESS     ;call sub ANYWHERE in page x
>
> ;in page x
> PAGE1SUBADDRESS:
> ....
>         return  ;since subroutine call pushed FULL address on the stack.
>
> For the 16F87x &  F73..
> You will return to caller. PCLATH is unchanged so your next call
> can have lower overhead if it's to the same the 2K page.
> Just remeber that you can't use any page 0 goto's until you
> clear PCLATH since the same PCLATH rules apply.
>
> "Call Subroutine. First, the 13 bit return address is pushed onto the
> stack. The 11 bit immediate address is loaded into PC, while the upper
> bits are loaded from PCLATH".
>
> Goto's do the same 11+2 (or in your case +1).
>
> I assume that C57 is simiar in behaviour to the '73.
>
> Robert
>
> Ian Hynes wrote:
> >
> > PICers,
> >
> > Suppose we have a 16C57 and, for convenience, we have all the LCD
> > routines, let's say, in PAGE 1 and we want to call them from PAGE 0.
> >
> >

>;****************************************************************
>;PAGE #1
>;****************************************************************
>        org     0x0200          ;Lower half
>
>lcdtx4   movlw    0x08
>         <.. Do things but NO further calls!>   ;Careful with the nest level
>         retlw    0x00
>
>
>test01   nop                    ;The routine gets data from a Page 0
>register
>         Page_0
>         Bank_0
>         movf     FWD_TIME,w    ;Load the RELAY ON time from page #0
>         Page_1
>         Bank_1
>         movwf    charac        ;And stores it in a Page 1 reg
>         call     lcdtx4        ;Then it calls another  Page 1 subroutine