Scalable Coherent Interface definition hardware, protocol
(SCI) The ANSI
that defines a point-to-point interface
and a set of packet protocols
. The SCI protocols use packets with a 16-byte header
and 16, 64, or 256 data bytes. Each packet is protected by a 16-bit CRC
The standard defines 1 Gbit/second serial fiber-optic
links and 1 Gbyte/second parallel
copper links. SCI has two unidirectional links that operate concurrently.
The SCI protocols support shared memory
by encapsulating bus
requests and responses into SCI request and response packets. Packet-based handshake
protocols guarantee reliable data delivery. A set of cache coherence protocols are defined to maintain cache coherence in a shared memory system. Message passing
is supported by a compatible subset of the SCI protocols. This protocol subset does not invoke SCI cache coherency protocols.
SCI uses 64-bit addressing
and the most significant 16 bits are used for addressing up to 64K nodes