Dear Seniors!!!

OK so here is my detailed question ... as said by Mr. Maniraj

1> I have program written for the LCD with 4 bit data bus interfacing with 4 * 4 Matrix Keyboard.

2> The task given me to is I have to take password from the user and authenticate it on that basis.

3> Intially the user will be provided with the default password and after getting access to the system, he can change thae password.

4> I have read the data sheet + the guidelines given by the gentelmans in this forum. But I am in the confusing state because I havent got the success yet.

5>
Jan said


I have my program starting from the subroutine START above the address 2000h like ...

                     org 2010h
                     ljmp START

       START:
             ;Soubroutines for the Lcd intialization and reading the key pressed by the matrix keyboard ..............
               

My confusion is ... I have read that after reset and before 400Ms I ahev swap in the IAP function flash area.

So I will have to modify the above program in the following way ...

                    org    2010h
   
   FLASH_API:
         PUSH    IE          ;DISABLE INTERRUPTS
         CLR     EA
         ANL     FCF,#0FCh   ;enable boot sector - !!! this command MUST be located ABOVE 2000h!!!
         CALL    01FF0H      ;call to ISP_API (modifies B register but no Rx)

after calling to IAP in the above statement here I have to call my START Subrouitne or after the last statement of this subrouitne I'll have to write my START subrouitne

         ORL     FCF,#001h   ;switch back to user FLASH
         POP     IE
         RET

6> I mean to say where I should call or write my subrouine after calling the IAP.

7> If still I am not been able to make you understand then revert me where are you finding probs.

waiting for the response ...

Thanks and Regards,
Arvind Shrivastava