Webopedia on Google+Webopedia on TwitterWebopedia on FacebookTech Bytes Blog
Main » TERM » N »

Native Command Queuing

Native Command Queuing (NCQ) is a command protocol in Serial ATA that can be implemented only on native Serial ATA hard drives. It allows multiple commands to be outstanding within a drive at the same time. Drives that support NCQ have an internal queue where outstanding commands can be dynamically rescheduled or re-ordered, along with the necessary tracking mechanisms for outstanding and completed portions of the workload. NCQ also has a mechanism that allows the host to issue additional commands to the drive while the drive is seeking data for another command.

NCQ allows the drive to set up the direct memory access (DMA) operation for a data transfer without host software intervention. This is also called first-party DMA - it means that the device is capable of complex sequences of operations without CPU intervention. The drive itself knows the current angular and rotational position of the drive head. The drive then selects the next data transfer to minimize both seek and rotational latencies.

* [Definition Source: Seagate Technology]

The Problem with Statistics

We look at a few of the more troubling aspects of statistics and how these may be used to advance an agenda or skew the facts to someone's... Read More »

29 Free Android Apps for Cash-Strapped Students

From wacky alarm clocks to lecture hall tools and after class entertainment, these Android apps are a good fit for a student's life and budget. Read More »

Sharing Threat Intelligence

A growing number of startups make the sharing of threat intelligence a key part of their solutions. Read More »

The 7 Layers of the OSI Model

The Open System Interconnection (OSI) model defines a networking framework to implement protocols in seven layers. Use this handy guide to compare... Read More »

Network Fundamentals Study Guide

Networking fundamentals teaches the building blocks of modern network design. Learn different types of networks, concepts, architecture and... Read More »

Computer Architecture Study Guide

This Webopedia  study guide describes the different parts of a computer system and their relations. Read More »