A computer that carries out computations on one number at a time.
A CPU that performs computations on one number or set of data at a time. Most computers have scalar CPUs. A scalar processor is known as a "single instruction stream single data stream" (SISD) CPU. Contrast with vector processor. See scalar.
Critical to this capability are high-performance three-dimensional graphics workstations with multiple scalar processors having total floating-point power of hundreds of megaflops; operating systems that support regularly scheduled preemptive lightweight threads, so that processes are reliably and regularly scheduled; and very large (more than 10 gigabytes) physical memory capability.
Other approaches to large multiprocessors do not have vector facilities, and hence may not be viable or performance/price competitive for highly vectorized applications since automatic compilation or parallel constructs to use a large number of scalar processors don't appear to offer the speed of the vector approach for these applications.