I came to this page expecting a compare and contrast between ATCA and CompactPCI, and instead got this ambiguous overview that barely ackowledges that ATCA is a peripheral interconnect standard.
This article should answer these questions:
1. What is ATCA? 2. How is it different from CompactPCI? 3. Who is expected to use it; who uses it now? 4. What are the specifications? 5. What does the connector look like?