1. Related Application
The present application relies for priority on Korean Patent Application Nos. 2003-49770, filed on Jul. 21, 2003 and 2004-36908, filed on May 24, 2004, the contents of which are incorporated herein in their entirety by reference.
2. Field of the Invention
The present invention relates to a double data rate synchronous semiconductor memory device, and more particularly, to a synchronous semiconductor memory device for inputting and outputting data using a free-running clock and inserting into the outputted data a preamble notifying a start of data.