http://www.vlsibank.com/titles.asp?cat=VHDL
http://www.51semi.com/
http://www.icedu.net/
http://www.edtn.com/search
http://www.hitex.com/chipdir/chipdir.htm
http://www.questlink.com.
http://www.info-quick.com/
http://www.questlink.com/
http://www.semi.com.tw/ - Search engine with over 45000 PDF datasheets
http://www.semidex.com/ - 60,000 memory IC*’s and boards and growing
http://www.chipfinder.com
http://groups.google.com/group/zhong1985624?hl=zh-CN