The Scalable Coherent Interface (SCI) originated in 1988. Those involved in the IEEE P896 Futurebus standards project realized that not even the best bus design would be able to support the needs of microprocessor multiprocessors within a few years. The SCI group searched for some new approach that would provide familiar bus-like services to the user but avoid the bottlenecks inherent in physical buses, scale up to high-end supercomputer performance, and support efficient software for parallel-processing systems and applications.
SCI abandoned the bus-specific parts of the Futurebus protocols that could not be scaled, in order to scale the performance up to higher levels. However, the general architecture was preserved as much as possible, in order to allow for easy interconnecting of Futurebus subsystems. Also, some features were added to facilitate interfacing to common buses like the VME bus and the PCI bus.