>But I using ram 256 MB sure it not supported.
I've run Win98FE and 256 megs of RAM with no problems (well, outside of the problems one normally has with Win9x). Win98 supports 256 MB of RAM, it just has a problem with greater than 512 due to a bug in the memory management system that uses all your space for disk caching. This can be worked around by adding two statements to your system.ini file:
MinFileCache=1024
MaxFileCache=131072 (For 512, recalculate for other mem sizes. This should be 25% of the total memory you have)
For more info check out
www.betanews.com, they had a feature on it a few weeks ago. Note that playing with these settings can be useful for even those with lower amounts of RAM, as Win98's defaults are more geared to computers of a few years ago (namely, those with 16 to 32 megs of RAM).
>Any OS support it???
Of course, it's always dependant on proper configuration.
UNIX-variants (Solaris, Linux, AUX), BeOS, QNX, Win NT 4 and higher (don't know about lower versions), Windows 2000...