ABSTRACT
In SIMD and MIMD architectures, several processors are connected with each other
and memory blocks through the interconnection network, in a tightly coupled manner. These systems typically reside in one or more cabinets in a room rather
than widely dispersed geographically. They cannot be easily expanded in small
increments, and typically employ only one type of processor and hence are not
suitable for environments with an array of specialized applications. They usually
employ a fixed interconnection topology, thereby restricting the users when the
applications dictate a different more efficient topology. Some modern SIMD and
MIMD systems have addressed these shortfalls by using heterogeneous processing
nodes and being scalable to fairly large number of nodes. They have also merged
the SIMD and MIMD concepts, as evidenced by the evolution of the Thinking
Machines’ Connection Machine series. The earlier machines in the series were
SIMDs while the CM-5 operates in both the modes.
