Hello All,
               Well thanks to Andy Warren and indeed all the members of the
PICLIST who sent replies to my PCLATH problem, I have finally managed to get
my code to work; I can now reliably cross page boundaries when processing
long text strings - brilliant. The problem was actually in the write_string
subroutine which Andy managed to spot; I would have never thought to modify
the PCLATH register here since the number of entries in the 'jump table' was
so little in comparison with the those of the actual text string look-up
tables.
         Actually the code which I recently sent to PICLIST was in fact the
wrong version; I have been struggling so much attempting to solve the problem
that I ended up at the stage where I was 'trying anything' without really
thinking, and in my panic I sent a version which incorrectly included the BSF
PCLATH,0. Just in case anyone on the list incorrectly thinks that the
exclusion of this instruction was the solution to my problem, then I have
included the subroutines of my working code.
           As I become more proficient with the PIC assembly language, I will
make a positive effort to help other members of the PICLIST solve their
problems.


Many thanks to all members, and best wishes: Lee Hewitt (Manchester ENGLAND)



write_string

        clrf          char_ptr        ;Clear character pointer to zero
        movwf   msg_ptr         ;Load message pointer with message number

ws1:    movlw   high (JUMP_TABLE)
              movwf     PCLATH
              clrc                                               ;Clear carry 'f
lag in status
register'
              rlf              msg_ptr,w                       ;Multiply by two
to prevent
pointing to goto
              addlw     low (JUMP_TABLE)     ;Computed GOTO string pointer
              btfsc     STATUS,C
              incf            PCLATH,f
              movwf     PCL


JUMP_TABLE:

           call string0         ;Get next character in the string
        goto    ws2             ;Upon return call ws2 to step through characters

        call    string1
        goto    ws2

        call    string2
        goto    ws2

      call      string3
        goto    ws2

        call    string4
        goto    ws2

        call    string5
        goto    ws2

        call    string6         ;fall into ws2 upon return


ws2:    movwf   temp1         ;store char returned from table in temp1
                xorlw   EOMSG   ;test for end of message marker (0x04)
                btfsc   ZERO          ;Zero set iff EOM is detected
                return                      ;End Of Message marker detected, thu
s return

                movf    temp1,w
                xorlw   EOLN          ;Test for EOL marker
                btfsc   ZERO
                goto    new_line_1

                movf    temp1,w
                call    send_lcd_char
tst             incf    char_ptr,f
                goto    ws1

new_line_1      movlw   NW_LINE ;send new line command to display
                call    send_lcd_cmd
                call    short_delay
                goto    tst



;Text string look-up tables

string0
        bcf     PCLATH,0
        movlw   high (TABLE_0)  ;Load HIGH byte
        movwf   PCLATH
        movlw   low (TABLE_0)   ;Load LOW byte
        addwf   char_ptr,w
        btfsc   STATUS,C
        incf    PCLATH,f
        movwf   PCL

TABLE_0 dt   "*** Power On ***",EOLN,"  Master Reset  ",EOMSG


string1 bcf     PCLATH,0
        movlw   high (TABLE_1)  ;Load HIGH byte
        movwf   PCLATH
        movlw   low (TABLE_1)   ;Load LOW byte
        addwf   char_ptr,w
        btfsc   STATUS,C
        INCF    PCLATH,f
        movwf   PCL

TABLE_1 dt   "Waiting For SOH",EOLN,"From Host PC ...",EOMSG


string2 bcf     PCLATH,0
        movlw   high (TABLE_2)  ;Load HIGH byte
        movwf   PCLATH
        movlw   low (TABLE_2)   ;Load LOW byte
        addwf   char_ptr,w
        btfsc   STATUS,C
        INCF    PCLATH,f
        movwf   PCL

TABLE_2 dt   " Connection Has ",EOLN,"Been Established",EOMSG


string3 bcf     PCLATH,0
        movlw   high (TABLE_3)  ;Load HIGH byte
        movwf   PCLATH
        movlw   low (TABLE_3)           ;Load LOW byte
        addwf   char_ptr,w
        btfsc   STATUS,C
        INCF    PCLATH,f
        movwf   PCL

TABLE_3 dt   "Waiting For STX",EOLN,"From Host PC ...",EOMSG


string4 bcf     PCLATH,0
        movlw   high (TABLE_4)  ;Load HIGH byte
        movwf   PCLATH
        movlw   low (TABLE_4)   ;Load LOW byte
        addwf   char_ptr,w
        btfsc   STATUS,C
        INCF    PCLATH,f
        movwf   PCL

TABLE_4 dt   "Receiving Config",EOLN," Data From Host ",EOMSG


string5 bcf     PCLATH,0
        movlw   high (TABLE_5)  ;Load HIGH byte
        movwf   PCLATH
        movlw   low (TABLE_5)   ;Load LOW byte
        addwf   char_ptr,w
        btfsc   STATUS,C
        INCF    PCLATH,f
        movwf   PCL

TABLE_5 dt   "Waiting For EOT",EOLN,"From Host PC ...",EOMSG


string6 bcf     PCLATH,0
        movlw   high (TABLE_6)  ;Load HIGH byte
        movwf   PCLATH
        movlw   low (TABLE_6)   ;Load LOW byte
        addwf   char_ptr,w
        btfsc   STATUS,C
        INCF    PCLATH,f
        movwf   PCL

TABLE_6 dt   " Data Transfer ",EOLN," *** Complete ***",EOMSG


******* End Of Program *******