What is SCI?

SCI stands for Scalable Coherent Interface, an ANSI/IEEE standard for the interconnection of computer components. This interconnect architecture allows processors, memories, and I/O devices be clustered into large distributed multiprocessor systems. SCI allows us to build scalable distributed systems based on both shared-memory and message-passing models.

Computer buses have served us for half a century but are now reaching their fundamental scalability limits. SCI combines the best of buses and networks in a unique way to overcome their limitations. It uses 16 bit wide point to point unidirectional interconnect, transferring data at a blazing 500 MHz achieving one gigabyte per second transfer rate.

The basic transfer unit in SCI is a packet, to eliminate the overhead of bus-cycles. The packet transport protocol guarantees forward progress. The optional cache coherency protocol is based upon distributed directory scheme using split-response transactions.

We have several products based on SCI standard,

SCI could best be described as "Local Area Multi-Processing".

Extensive information on SCI and related standards/activities is maintained by SCIzzL, the SLDRAM Trade Association, and the Association of Scalable Coherent Interface Local Area MultiProcessor Users, Developers, and Manufacturers.