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BIRD ID#:        99.1
ISSUE TITLE:     AMS Language Versions
REQUESTER:       Arpad Muranyi, Intel Corp.
DATE SUBMITTED:  June 10, 2005
DATE REVISED:    July 15, 2005
DATE ACCEPTED BY IBIS OPEN FORUM:  August 5, 2005

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STATEMENT OF THE ISSUE:

Careful studies of various versions of the Verilog-AMS language reference
manuals (LRM v2.0, v2.1 and v2.2) revealed that the newer versions contain
useful and much needed features for making I/O buffer modeling easier (for 
example $table_model).  Most vendors have already implemented some of these
features in their simulators, becuase of their usefulness.

Considering the relatively infrequent releases of the new revisions of the
IBIS specification, referencing single and fixed version numbers for the AMS
language extensions can paralize the growth in high quality model making.

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STATEMENT OF THE RESOLVED SPECIFICATIONS:

The IBIS specification shall not specify a single and exact version number 
for the *-AMS language extensions.  The IBIS specification shall refer to
these version numbers only as a minimum requirement, but not as an absolute
requirement.

The following section in the IBIS specification shall be modified:

|
| LANGUAGES SUPPORTED:
|
| IBIS files can reference other files which are written using the SPICE,
| VHDL-AMS, or Verilog-AMS languages.  In this document, these languages are
| defined as follows:
|
| "SPICE" refers to SPICE 3, Version 3F5 developed by the University of
| California at Berkeley, California.  Many vendor-specific EDA tools are
| compatible with most or all of this version.
|
| "VHDL-AMS" refers to "IEEE Standard VHDL Analog and Mixed-Signal
| Extensions", approved March 18, 1999 by the IEEE-SA Standards Board and
| designated IEEE Std. 1076.1-1999.
|
| "Verilog-AMS" refers to the Analog and Mixed-Signal Extensions to
| Verilog-HDL as documented in the Verilog-AMS Language Reference, Version
| 2.0.  This document is maintained by Accellera (formerly Open Verilog
| International), an independent organization.  Verilog-AMS is a superset
| that includes Verilog-A and the Verilog Hardware Description Language
| IEEE 1364-2001.
|
| In addition the "IEEE Standard Multivalue Logic System for VHDL Model
| Interoperability (Std_logic_1164)" designated IEEE Std. 1164-1993 is
| required to promote common digital data types.
| 

and replaced with the following:

| LANGUAGES SUPPORTED:
|
| IBIS files can reference other files which are written using the SPICE,
| VHDL-AMS, or Verilog-AMS languages.  In this document, these languages are
| defined as follows:
|
| "SPICE" refers to SPICE 3, Version 3F5 developed by the University of
| California at Berkeley, California.  Many vendor-specific EDA tools are
| compatible with most or all of this version.
|
| "VHDL-AMS" refers to "IEEE Standard VHDL Analog and Mixed-Signal
| Extensions", approved March 18, 1999 by the IEEE-SA Standards Board and
|* designated IEEE Std. 1076.1-1999, or later.
|
| "Verilog-AMS" refers to the Analog and Mixed-Signal Extensions to
| Verilog-HDL as documented in the Verilog-AMS Language Reference, Version
|* 2.0, or later.  This document is maintained by Accellera (formerly Open
| Verilog International), an independent organization.  Verilog-AMS is a
| superset that includes Verilog-A and the Verilog Hardware Description
| Language IEEE 1364-2001.
|
| In addition the "IEEE Standard Multivalue Logic System for VHDL Model
|* Interoperability (Std_logic_1164)" designated IEEE Std. 1164-1993, or 
|* later is required to promote common digital data types.
| 

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ANALYSIS PATH/DATA THAT LED TO SPECIFICATION


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ANY OTHER BACKGROUND INFORMATION:

Based on the request by Bob Ross in the July 14, 2005 IBIS Open Forum
teleconference, the change in the version number definition for Berkely
SPICE was removed.  The reason is that Berkeley SPICE is not being developed
by any one any more, and Version 3F5 appears to be a final version.

A brief discussion on this subject in the June 3, 2005 IBIS Open Forum 
Teleconference indicated that most participants would be in favor of 
replacing the exact version numbers spelled out in the IBIS specification 
for the AMS languages with a more flexible definition that sets a minimum 
expectation without limiting growth.

Similar opinions were expressed by signal integrity experts in the industry
during private discussions in the month of April and May of 2005.

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