The VHDL behavioral model for the Distributed Memory Generator v4.1 Rev1 Core drives an unknown value on DOUT for a Spartan-6 design.
This issue only occurs when using the VHDL behavioral model and only when both the Reset and Synchronous reset options are set to false in the GUI. The DOUT bus will correctly drive data when a read is performed.
This issue will be fixed in the next version of the core released with ISE 11.3.
06/24/2009 - Initial Release