Todd, I would like to add a few more items to your list on why (and how) some AMI models are non-compliant. I don't know if I can mention the company name openly, but there are some released AMI DLL-s which use a certain parameter format that is not AMI spec compliant. The answer I was given when I questioned this was that these models existed before the AMI spec was finished, and it would be too much work for the IC vendor to rewrite their models to obey the AMI syntax. I understand that Walter's proposed AMI BIRD contains changes that will make these models compliant, but for the time being they will only work with tools which are willing to support them out-of-spec. While I agree with your discussion about S-parameters, I would like to mention that I have seen non-compliant .ibs files in which there were no S-parameter references and many of the non-compliant features could have been described by simple, existing IBIS syntax. Also, I have seen files which do not pass the parser because they contain obvious spec violations, such as not having a number in the typical column of various items, or omitting required keywords and/or subparameters, or even because of the incorrect spelling of the OS under the brand new [Algorithmic Model] keyword. One could call these problems accidental mistakes or typos, but that's what we have a parser for, right? Arpad =================================================================== -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Todd Westerhoff Sent: Monday, February 08, 2010 9:25 AM To: Eric Monteiro Cc: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: IBIS-AMI Vendor Support Help All, ... ... Why would a model ever be non-compliant? There are two main reasons. The first (and possibly the issue Eric was raising) is that the simulator vendor may not fully support the standard. The .ami file is a "control file" that tells the simulator how to load and execute the .dll, and what model configuration options are available. From what I've seen, some vendors don't support this fully, and require a tool-specific model control file instead. It's usually the same information in a different format, but it does require that the user understand the details of a proprietary modeling format. The second reason a model might be non-compliant is that is uses extensions to IBIS-AMI that haven't been accepted as part of the standard yet. A good example of this is the use of S-parameter data in place of the analog model. The 5.0 IBIS spec doesn't readily lend itself to describing the broadband behavior of analog I/O. IBM, Cisco and SiSoft proposed a method for dealing with this in February 2009: http://www.vhdl.org/pub/ibis/summits/feb09/hawes.pdf Although the exact syntax for this capability is still in discussion, there *ARE* models out there that use this syntax, or something very similar. There are a number of semiconductor vendors that use S-parameter data to characterize the analog aspects of their I/O, and there's no good reason, in my opinion, to compromise model accuracy because we haven't settled on the final syntax for the standard. The consequence of this is that the S-parameter data gets included in a slightly different fashion between tools, but the purpose and the S-parameter data are the same. Claiming that a model "isn't compliant!" and "doesn't work out of the box!" may make for a good sound bite, but this isn't rocket science, especially since the proposed method and syntax have been documented publicly. ... ... I'm sure the discussion will continue, so I'm going to leave off here for now. Todd. Todd Westerhoff VP, Software Products SiSoft 6 Clock Tower Place, Suite 250 Maynard, MA 01754 (978) 461-0449 x24 twesterh@xxxxxxxxxx www.sisoft.com ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu