internal eeprom pic16f628

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pic16f628 eeprom

dear all
m trying to use internal eeprom of pic16f628 to read and write data .this is the code below .m not getting the correct output .please help me find the mistake

LIST   p=16F628a      ;tell assembler what chip we are using 
   include "P16F628a.inc"      ;include the defaults for the chip 
   ERRORLEVEL   0,   -302   ;suppress bank selection messages 
   __CONFIG _CP_OFF & _WDT_OFF & _INTRC_OSC_NOCLKOUT & _PWRTE_ON & _LVP_OFF & _BODEN_OFF & _MCLRE_OFF 




      cblock   0x20         ;start of general purpose registers 
         count         ;used in looping routines 
         count1         ;used in delay routine 
         counta         ;used in delay routine 
         countb         ;used in delay routine 

         prom_ADDR 
         prom_DATA 

    
      endc 



      org   0x0000 

      movlw   0x07 
      movwf   CMCON         ;turn comparators off (make it like a 16F84) 

Initialise   clrf   count 
      clrf   PORTA 
      clrf   PORTB 
      clrf   prom_ADDR 
      clrf   prom_DATA 


SetPorts   bsf    STATUS,      RP0   ;select bank 1 
      movlw   0x00         ;make all pins outputs 
      movwf   TRISA 
      movwf   TRISB 
      bcf    STATUS,      RP0   ;select bank 0 

    


      call   Delay255 
      call   Delay255 
      call   Delay255 
      call   Delay255 


      movlw    0x50 
      movwf   prom_ADDR 
      movlw    0x12 
      movwf   prom_DATA 
      call   write_eeprom 
       
      call    Delay20 




      movlw   0x50 
      movwf   prom_ADDR 
      call   read_eeprom 

      movf   prom_DATA, w 
      movwf   PORTB 

stop   goto   stop 

;Subroutines 

write_eeprom 

      BSF STATUS, RP0 ;Bank 1 
       
      movlw    prom_ADDR 
      movwf   EEADR 
      movf   prom_DATA, w 
      movwf   EEDATA    
       
      BSF EECON1, WREN ;Enable write 
      ;BCF INTCON, GIE ;Disable INTs. 
      MOVLW 0x55 ; 
      MOVWF EECON2 ;Write 55h 
      MOVLW 0xAA ; 
      MOVWF EECON2 ;Write AAh 
      BSF EECON1,WR ;Set WR bit 
                  ;begin write 
      ;BSF INTCON, GIE ;Enable INTs. 

      BCF    STATUS, RP0 ;Bank 0 
      retlw   0x00    








read_eeprom 
      BSF    STATUS, RP0 ;Bank 1 
      MOVLW    prom_ADDR    ; 
      MOVWF    EEADR ;Address to read 
      BSF    EECON1, RD ;EE Read 
      MOVF    EEDATA, W ;W = EEDATA 
      movwf   prom_DATA 
      BCF    STATUS, RP0 ;Bank 0 
       
      return 




Delay255   movlw   0xff      ;delay 255 mS 
      goto   d0 
Delay100   movlw   d'100'      ;delay 100mS 
      goto   d0 
Delay50      movlw   d'50'      ;delay 50mS 
      goto   d0 
Delay20      movlw   d'20'      ;delay 20mS 
      goto   d0 
Delay5      movlw   0x05      ;delay 5.000 ms (4 MHz clock) 
d0      movwf   count1 
d1      movlw   0xC7         ;delay 1mS 
      movwf   counta 
      movlw   0x01 
      movwf   countb 
Delay_0 
      decfsz   counta, f 
      goto   $+2 
      decfsz   countb, f 
      goto   Delay_0 

      decfsz   count1   ,f 
      goto   d1 
      retlw   0x00 



      end