operations, and level 3 BLAS includes matrix-matrix operations. BLAS subroutines are frequently optimized for each specific hardware platform.


Blue Gene/Light (IBM).


A small, fast storage area close to the central processing unit (CPU) of a computer that holds the most frequently used memory contents. Caches aim to provide the illusion of a memory as large as the main computer memory with fast performance. They succeed in doing so if memory accesses have good temporal locality and good spatial locality.

cache line.

The unit of data that is moved between cache and memory. It typically consists of 64 or 128 consecutive bytes (8 or 16 consecutive double words).

cache memory system.

Modern computers typically have multiple levels of caches (named level 1, level 2, and so on) that are progressively larger and slower; together they comprise the cache memory system.


Computer-aided engineering. The construction and analysis of objects using virtual computer models. This may include activities of design, planning, construction, analysis, and production planning and preparation.

capability computing.

The use of the most powerful supercomputers to solve the largest and most demanding problems, in contrast to capacity computing. The main figure of merit in capability computing is time to solution. In capability computing, a system is often dedicated to running one problem.

capacity computing.

The use of smaller and less expensive high-performance systems to run parallel problems with more modest computational requirements, in contrast to capability computing. The main figure of merit in capacity computing is the cost/performance ratio.


Community Climate System Model.


Control Data Corporation.

circuit speed.

Time required for a signal to propagate through a circuit, measured in picoseconds per gate. It is a key aspect of processor performance.


The NSF Directorate for Computing and Information Science and Engineering. This directorate is responsible for NSF-funded supercomputing centers.

clock rate or clock speed.

The frequency of the clock that drives the operation of a CPU, measured in gigahertz (GHz). Clock rate and instructions per cycle (IPC) determine the rate at which a CPU executes instructions.


A group of computers connected by a high-speed network that work together as if they were one machine with multiple CPUs.

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