Not sure if anyone has this kind of info (may have to go back to Atmel for it, or spend a lot more time looking thru my program and device specs to figure it out :(

I am working on a design that uses the AT89C51RC. I've had a prototype up and running and seemed to be working fine. I got a couple of AT89C51RC2 devices (superset of AT89C51RC w/PCA, X2 clock, ISP FLASH programming, etc.) from Atmel. I thought I would be able to just plug and play with the 'RC2, but the program does not work. I've swapped in and out a number of other 8XC51 devices and all seem to function as expected except the 'RC2. BTW - I'm currently using external program memory until I finalize the code.

I'm wondering if anyone is familiar with this device and could offer any suggestions about why this would happen. I figure my program may assume something about the initial state of the '51 that may not be true for the 'RC2 version (or I've accidentally written a bit into an SFR that would normally be "don't care" but the 'RC2 may actually care a lot :(

Thanks in advance for any help offered.

Cheers....Steph