Scalar processor
Encyclopedia
Scalar processors represent the simplest class of computer processors. A scalar processor processes one datum at a time (typical data items being integer
s or floating point numbers). , a scalar processor is classified as a SISD
processor (Single Instructions, Single Data).
In a vector processor
, by contrast, a single instruction operates simultaneously on multiple data items. The difference is analogous to the difference between scalar
and vector arithmetic.
A superscalar
processor, on the other hand, executes more than one instruction during a clock cycle by simultaneously dispatching multiple instructions to redundant functional units on the processor. Each functional unit is not a separate CPU core but an execution resource within a single CPU such as an arithmetic logic unit, a bit shifter, or a multiplier.
Integer (computer science)
In computer science, an integer is a datum of integral data type, a data type which represents some finite subset of the mathematical integers. Integral data types may be of different sizes and may or may not be allowed to contain negative values....
s or floating point numbers). , a scalar processor is classified as a SISD
SISD
In computing, SISD is a term referring to a computer architecture in which a single processor, a uniprocessor, executes a single instruction stream, to operate on data stored in a single memory. This corresponds to the von Neumann architecture.SISD is one of the four main classifications as...
processor (Single Instructions, Single Data).
In a vector processor
Vector processor
A vector processor, or array processor, is a central processing unit that implements an instruction set containing instructions that operate on one-dimensional arrays of data called vectors. This is in contrast to a scalar processor, whose instructions operate on single data items...
, by contrast, a single instruction operates simultaneously on multiple data items. The difference is analogous to the difference between scalar
Scalar (mathematics)
In linear algebra, real numbers are called scalars and relate to vectors in a vector space through the operation of scalar multiplication, in which a vector can be multiplied by a number to produce another vector....
and vector arithmetic.
A superscalar
Superscalar
A superscalar CPU architecture implements a form of parallelism called instruction level parallelism within a single processor. It therefore allows faster CPU throughput than would otherwise be possible at a given clock rate...
processor, on the other hand, executes more than one instruction during a clock cycle by simultaneously dispatching multiple instructions to redundant functional units on the processor. Each functional unit is not a separate CPU core but an execution resource within a single CPU such as an arithmetic logic unit, a bit shifter, or a multiplier.