Mike,

Correction:
ORG 00H
AGAIN:
MOV A, #0AAH ; LOAD A WITH AAh VALUE
MOV DPTR, #0000H ; LOAD ADDRESS IN DPTR
MOV 8EH, #00000011B ; SET EXTERNAL RAM ACCESS
MOVX @DPTR, A ; MOV AA out to 0000h
MOV P1,A
CALL DELAY_50mSec
MOV A, #00H ; clear out A
MOVX A, @DPTR ; move AAh back into A
MOV P1,A
CALL DELAY_50mSec
JMP AGAIN ; keep doing it
END

I use the serial port as a debug tool, instead of LEDs. You would send the value of the accumulator in ASCII hex out through the serial port. Call SENDVAL at the point where you wish to see what is going on.

;SENDVAL
; converts the hex value of A into two ASCII chars, and then spits
; these two characters up the UART. does not change the value of A.

SENDVAL:
MOV R7,A
SWAP A
CALL HEX2ASCII
CALL SENDCHAR ; send high nibble
MOV A,R7
CALL HEX2ASCII
CALL SENDCHAR ; send low nibble
MOV A,R7
RET

; HEX2ASCII
; converts A into the hex character representing the value of A's
; least significant nibble

HEX2ASCII:

ANL A,#00Fh
CJNE A,#00Ah,$+3
JC IO0030
ADD A,#007h
IO0030: ADD A,#'0'
RET

Have fun debugging ;)

Jacob