Chuck,

I would add that the VHDL standards groups are doing things

to compel you to move in this direction.

The plan for VHDL-2006 is for std_logic_1164 and numeric_std

to be included as part of 1076. Another part of the plan is to

expand what is locally static to allow array operations.

Combine both of these and array operations (from std.standard,

std_logic_1164, and numeric_std) within a case statement

will be permitted.

While this does not prevent people from using std_logic_arith,

std_logic_arith is not an IEEE standard and hence operations

in this package will not be locally static.

Best Regards,

Jim Lewis

P.S.

Current plans for vhdl-2006 is to include a new package

called numeric_std_unsigned.

> We are working on a second edition of "Digital Systems Design Using VHDL".

> The present edition uses the std_logic_arith or std_logic_unsigned

> package for arithmetic operations. We are debating whether to switch to

> numeric_std for some of the examples in the textbook. Our question is: How

> widely used is the numeric_std package in practice?

>

> -- Charles H. Roth, UT Austin
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Jim Lewis

Director of Training (E-Mail Removed)

SynthWorks Design Inc.

http://www.SynthWorks.com
1-503-590-4787

Expert VHDL Training for Hardware Design and Verification

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