Hi Sanjay,

While I haven't used the chip you describe, the atmel part should be pin-for-pin compatible with it's older less capable sibling, the 80C51. Normally, while you can substitute the 80C51 with an AT89C51RD2, you cannot go the other way around, because the 'RD2 is infact a souped-up 80C52 and all the extra features that you will not find in a standard 8051.

I just don't understand why atmel didn't call it an AT89C52RD2 because that would've been more accurate - throws me everytime I search for 8052-type parts! : /

Both chips will utilise the same MCS-51 instruction set, as far as I know..

Valentin