Scalar processor: Difference between revisions

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{{Short description|Class of computer processors}}

{{refimprove|date=August 2012}}

'''Scalar processors''' representare a class of [[computer processor]]s. Athat scalar processor processesprocess only one data item at a time,. with typicalTypical data items beinginclude [[integer (computer science)|integer]]s orand [[floating point number]]s.<ref name="Ram 2001 p. 11">{{cite book | last=Ram | first=Badri | title=Advanced microprocessors and interfacing | publisher=Tata McGraw-Hill Pub. Co | publication-place=New Delhi | year=2001 | isbn=978-0-07-043448-6 | oclc=55946893 | page=11}}</ref>

== Classification ==

A scalar processor is classified as a single instruction, single data ([[Single instruction, single data|SISD]]) processor in [[Flynn's taxonomy]]. The [[i486|Intel 486]] is an example of a scalar processor. It is to be contrasted with a [[vector processor]] where a single instruction operates simultaneously on multiple data items (and thus is referred to as a single instruction, multiple data ([[Single instruction, multiple data|SIMD]]) processor).<ref name="Patterson 2012 p. 650">{{cite book | last=Patterson | first=David | title=Computer organization and design: the hardware/software interface | publisher=Morgan Kaufmann | publication-place=Waltham, MA | year=2012 | isbn=978-0-12-374750-1 | oclc=746618653 | page=650}}</ref> The difference is analogous to the difference between [[scalar (mathematics)|scalar]] and [[Vector (geometric)|vector]] arithmetic.

The term ''scalar'' in computing dates to the 1970 and 1980s when vector processors were first introduced. It was originally used to distinguish the older designs from the new vector processors.

== SuperscalerSuperscalar processor ==

A [[superscalar]] processor (such as the [[P5 (microarchitecture)|Intel P5]]), on the other hand, may execute 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.<ref name="Ram 2001 p. 11" /> The [[Cortex-M7]], like many consumer [[Central processing unit|CPUs]] today, is a superscalar processor.<ref>{{cite web | title=Cortex-M7 | website=Arm Developer | publisher=Arm Limited | url=https://developer.arm.com/ip-products/processors/cortex-m/cortex-m7 | access-date=2021-07-03}}</ref>

== Scalar data type ==

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Generally, all basic [[primitive data type]]s are considered scalar:

* The [[booleanBoolean data type]] (<code>bool</code>)

* Numeric types (<code>[[Integer (computer science)|int]]</code>, the [[floating point]] types <code>float</code> and <code>double</code>)

* Character types (<code>[[Character (computer science)#char|char]]</code> and <code>[[String (computer science)|string]]</code>)

Some programming languages also treat [[String (computer science)|strings]] as scalar types, while other languages treat strings as [[Array (data structure)|arrays]] or [[Object (computer science)|objects]].

==See also==

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{{DEFAULTSORT:Scalar Processor}}

[[Category:Central processing unit]]

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