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AR# 10713

3.1i CORE Generator - 8b10b Decoder v1_0 - Incorrect "code_err" and disparity checks are displayed


Keywords: CORE Generator, COREGen, Encoder, Decoder, 8b/10b, disparity, code_err

Urgency: Standard

General Description:
Version 1.0 of the 8b/10b Decoder core will give incorrect disparity checks and "code_err" flags for some of the symbols.

The incorrect flags occur on certain combinations of the lower six bits of the input symbol. These the incorrect symbol errors can be seen in the behavioral models in the b6 (the lower 6-bit block) process.

WHEN "000110" => b6_disp <= neg ; --D.0
b6_err <= FALSE; -- RF: Found a bug here: true;

WHEN "100111" => b6_disp <= pos ; --D.8
b6_err <= FALSE; -- RF: BUG found here: true;

WHEN "110011" => b6_disp <= neg; -- RF: found bug here pos ; --D.24
b6_err <= false ;


This issue has been fixed in Version 2_0 of 8b/10b Decoder, which is available in IP_Update#3 (D_IP3) and newer IP updates.

For the latest IP updates, go to the Xilinx IP center:
AR# 10713
Date Created 01/03/2001
Last Updated 08/23/2002
Status Archive
Type General Article