Thanks David.

Yes, the AT89S8253 board use:
"It just uses its internal RAM and stores non-volatile data in its internal EEPROM. And the program is run from its internal FLASH."

But why my predecessor (he passed away)defined like this:

;---------------------------------------------
; EEPROM DATA - AT89S8252
;---------------------------------------------
; ORDER TABLE
; To read rom we must locate
; it after 127 (7F hex)
; ram addresses
cseg at 2000H
;
; Location of charactor data.
; Position data or order
; Enter the order that the floors shall be in.
;To define a message DB Mess?," " include a space so each input is made up of 2 bytes.
;
ORDER: DB " "
DB "B " ;Flr1
DB "G " ;Flr2
.....
DB " " ;Flr62 =
DB " " ;Flr63 =


MX: DB Mess1 ;Message 1 "Out Of Service"
;XLX: DB CHX-1000H,CHX-1000H ; = -X-

cseg at 2082h
DB 06h ;2082h Scroll speed
DB 20h ;2083h
DB 01h ;2084h Scrolling off/on
DB 20h ;2085h
DB 080h ;2086h Flr Input brightness
DB 20h ;2087h
DB 01h ;2088h Arrow Type
DB 20h ;2089h
DB 05h ;208ah Message Speed
DB 01h ;208bh Input type clock/direct
DB 10d ;208ch OS Time in seconds

ORG 20A0h
DW Message1-2000h
DW Message2-2000h
.....
DW Message62-2000h
DW Message63-2000h

cseg at 2140h
;Start of message file determines
; 1. "01" = Hard on.
; 2. "02" = Scroll right to left.
; 3. "03" = Scroll left to right.
; 4. "04" = Hard on and flash.
........

It works after I change all 2000h to 3000h (as posted previously). I will have to examine the code carefully again.