COPYRIGHT (c) 2006, 2007 XILINX, INC.
ALL RIGHTS RESERVED

Core name            : FIFO Generator 
Version              : v4.1
Release Date         : August 8, 2007
File                 : fifo_generator_release_notes.txt

Revision History
Date     By            Version   Change Description
========================================================================
09/2006  Xilinx, Inc.  3.2       Initial creation.
02/2007  Xilinx, Inc.  3.3       Revised for v3.3.
02/2007  Xilinx, Inc.  3.3       Revised for v3.3 rev 1.
08/2007  Xilinx, Inc.  3.4       Revised for v4.1.
========================================================================

INTRODUCTION
RELEASE NOTES
  1. General Core Design
    1.1 Enhancements
    1.2 Resolved Issues
    1.3 Outstanding Issues
  2. General Simulation
    2.1 Enhancements
    2.2 Resolved Issues
    2.3 Outstanding Issues
  3. Documentation
    3.1 Enhancements
    3.2 Resolved Issues
    3.3 Outstanding Issues
OTHER GENERAL INFORMATION
TECHNICAL SUPPORT

========================================================================

INTRODUCTION
============
Thank you using the FIFO Generator core from Xilinx!  
In order to obtain the latest core updates and documentation, 
please visit the Intellectual Property page located at:
http://www.xilinx.com/ipcenter/index.htm
This document contains the release notes for FIFO Generator v4.1
which includes enhancements, resolved issues and outstanding known
issues.  For release notes and known issues for CORE Generator 9.2i IP
Update 1 and FIFO Generator v4.1 please see Answer Record 25222.

RELEASE NOTES
=============
This section lists any enhancements, resolved issues and outstanding
known issues.


1. General Core Design
  1.1 Enhancements
    1.1.1 Error Correction Checking (ECC) feature support for 
          Virtex-5 block RAM FIFO configurations

    1.1.2 Full range data count widths now supported for non-symmetric
          aspect ratio configurations

    1.1.3 Option to define asynchronous reset value for full condition 
          flags (FULL, ALMOST_FULL, PROG_FULL).  Applies to block RAM, 
          distributed RAM and shift RAM-based FIFO configurations only

    1.1.4 Support added for use embedded output registers in block RAM
          FIFO configurations (Virtex-4 and Virtex-5 only)

  1.2 Resolved Issues
    1.2.1 Coregen GUI - For built-in FIFOs,  GUI reports incorrect
          number of built-in FIFO primitives used.
          Change request: 4433738

    1.2.2 Programmable full flag is always asserted even when FIFO is 
          empty due to incorrect threshold setting.
          Change request: 435835
    
    1.2.3 "ERROR:LIT:250 - Pins WEA0, WEA1, WEA2, WEA3 of RAMB16 symbol
          .. , these pins should be connected to the same signal" occur
          during MAP when targeting Virtex-4 and Virtex-5.
          Change request: 338260

    1.2.4 Write Data Count and Read Data Count overestimate the number
          of words written or read when core is configured with this 
          combination of options: First-Word-Fall-Through(FWFT),
          accurate data count using extra logic, non-symmetric port
          aspect ratio.
          Change request: 436886

   1.2.5  SBITERR and DBITERR outputs are not driven in behavior
          models.
          Change request: 433637

   1.2.6  Maximum programmable empty threshold negate value is 
          incorrect.
          Change request: 433921

   1.2.7  Programmable full flag behavior is incorrect when the 
          core is configured with this combination of options:
          FWFT, non-symmetric port aspect ratio, single or 
          multiple programmable full threshold input port.
          Change request: 435874

   1.2.8  Programmable empty flag stuck high when the core is
          configured with this combination of options: block or
          distributed RAM FIFO, single or multiple programmable 
          empty threshold input port.
          Change request: 443569

  1.3 Outstanding Issues
    1.3.1 "WARNING:Ngdbuild:452 - logical net 
          'u1/BU2/prog_*_thresh_assert<*>' has no driver" occur during 
          NgdBuild although programmable empty or full is not selected.          
          Warnings can be safely ignored.
          Change request: 431975

2. General Simulation
  2.1 Enhancements
      None at this time.

  2.2 Resolved Issues
      None at this time.

  2.3 Outstanding Issues
    2.3.1 Ncelab warnings during Verilog structural and timing simulations 
          in ncsim for Virtex5 Block RAM FIFOs. 
          The simulations will be successful, but there will be warnings 
          similar to the following in the log file: "memory index out of 
          declared bounds" in simprims_ver_virtex5_source.v or 
          unisims_ver_virtex5_source.v.  Cadence does not want to fix this 
          issue. These warning messages can safely be ignored.
          Change request: 423374, 423375

3. Documentation
  3.1 Enhancements
    3.1.1 Added clarification on FIFO flag latency.
  
    3.1.1 Added clarification on actual FIFO depth.    

  3.2 Resolved Issues
      None at this time.
      
  3.3 Outstanding Issues
      None at this time.


TECHNICAL SUPPORT
=================
The fastest method for obtaining specific technical support for the 
FIFO Generator core is through the http://support.xilinx.com/
website. Questions are routed to a team of engineers with specific
expertise in using the FIFO Generator core.  Xilinx will provide
technical support for use of this product as described in the FIFO 
Generator Datasheet. Xilinx cannot guarantee timing, functionality, 
or support of this product for designs that do not follow these 
guidelines.