Presently i downloaded datasheet from the keil's website. but it's very old then what i found on the ramtron's website.
Please update this link.
Regards, Mihir
"it is my opinion that accessing datasheets anywhere but at the manufacturers website is sheer folly"
I wouldn't go as far as to call it sheer folly, but I would thouroughly agree that your primary source of reference should always be the actual manufacturer.
Only if the information cannot be obtained from the manufacturer (eg, obsolete/discontinued parts) should you consider 3rd party sites.
If a manufacturer will not provide the necessary documentation for a current part, that should be a very powerful reason not to use that part!