Hi:
It depends on what you mean. By "system architecture", do you mean the conceptual design that defines the structure and/or behavior of some piece of the SAS system?? And then if that's what you mean by system architecture, then you need to provide some context for your question. You could mean the system architecture of Foundation SAS; you could mean the system architecture or conceptual design of the SAS Platform for Business Analytics or Business Intelligence or you could mean the system architecture for one of the SAS solutions, such as Customer Relationship Management or Marketing Automation.
There is a LOT you could find out by using a search engine at any of these sites:
www.sas.com, www.google.com, support.sas.com -- there have been many papers on the system architecture of the SAS Platform for Business Analytics (also known as the BI Platform).
cynthia