Browse Definitions :
Definition

Q format

Q (number) format is a fixed-point method of coding fractional and whole integers for processing by a computer’s CPU or a digital signal processor (DSP).

The Q format is used to enable rational number processing by a standard integer hardware arithmetic logic unit (ALU). Q format is used frequently when a CPU lacks a floating point unit (FPU). The format can also be useful for processing fractions on lower-cost DSPs, reducing hardware costs.

To enable processing of fractions on lower-cost or older hardware, Q is used to imply a binary point to represent fractions. Q format is stored and processed as regular binary signed integer. The Q format specifies how many bits are used to represent whole integers and how many bits are used to represent fractional integers. For example, to note that an algorithm is using one bit to specify whole integers and 15 bits to specify fractional integers, one would use the Q1.15 format. If there is no decimal in a Q format, such as Q55, that implies all bits are used for fractional values.

An example of how a fraction is processed under the Q format would be the real number 5.375 represented as a=0×23+1×22+0×21+1×20+0×2−1+1×2−2+1×2−3+0×2−4=5.375.

The Q format was integral to fractional operations in early PC CPUs. The Intel 8086 was the first CPU to support an add-on floating point co-processor. These co-processors reduced the time spent processing fractions and the need for methods like Q format. Modern CPUs such as the Intel Core series and AMD Ryzen have built-in floating point processors along with the x87 extension on the x86 -64 instruction set.

This was last updated in January 2018

Continue Reading About Q format

Networking
  • network management system

    A network management system, or NMS, is an application or set of applications that lets network engineers manage a network's ...

  • host (in computing)

    A host is a computer or other device that communicates with other hosts on a network.

  • Network as a Service (NaaS)

    Network as a service, or NaaS, is a business model for delivering enterprise WAN services virtually on a subscription basis.

Security
CIO
  • digital disruption

    Digital disruption is the change that occurs when new digital technologies and business models affect the value proposition of ...

  • value stream management

    Value stream management is an emerging business process intended to gauge the flow of value into business resources and ...

  • audit program (audit plan)

    An audit program, also called an audit plan, is an action plan that documents what procedures an auditor will follow to validate ...

HRSoftware
  • team collaboration

    Team collaboration is a communication and project management approach that emphasizes teamwork, innovative thinking and equal ...

  • employee self-service (ESS)

    Employee self-service (ESS) is a widely used human resources technology that enables employees to perform many job-related ...

  • learning experience platform (LXP)

    A learning experience platform (LXP) is an AI-driven peer learning experience platform delivered using software as a service (...

Customer Experience
  • shoppable video

    A shoppable video is a way for consumers to discover products and make a purchase through links within the video.

  • Net Promoter Score (NPS)

    Net Promoter Score (NPS) is a metric that organizations use for assessing customer loyalty toward their brand, products or ...

  • B2C (business-to-consumer)

    B2C, or business-to-consumer, is a retail model where products or services move directly from a business to the end user who has ...

Close