Hi,

I am using Atmel uC AT89C55WD, but now i want bigger memory, then I choose P89C51RC2(32KB). I've been accessed to an external 32K RAM with an Atmel 89C55WD,and working OK. But I put the same code into P89C51RC2 and am having trouble such as no WR, RD pulses. I wrote a test in which the micro would write a byte then read it back for every memory location on the chip. I use the same code with the same
demo board. Please help

$MOD51

ORG 00H
START:
MOV R7,#64
MOV DPTR,#00H ;point 1st location
EXT:
MOVX A,@DPTR ;Read data from XRAM
MOV A,#0AAH
MOVX @DPTR,A ;write to XRAM
MOVX A,@DPTR
CJNE A,#0AAH,FAIL
MOVX @DPTR,A ;Write to mem. location
INC DPTR ;Next location
DJNZ R7,EXT
FAIL: SETB P1.7
SJMP START
END