access time

access time

Computing the time required to retrieve a piece of stored information

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

access time

[′ak·ses ‚tīm]

(computer science)

The time period required for reading out of or writing into the computer memory.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

access time

(hardware, storage)

The average time interval between a storage peripheral (usually a disk drive or semiconductor memory) receiving a request to read or write a certain location and returning the value read or completing the write.

This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)

access time

(1) Memory access time is how long it takes for a character in RAM to be transferred to or from the CPU. Fast RAM chips have an access time of 10 nanoseconds (ns) or less. See SDRAM.

(2) Disk access time is how long it takes to obtain the first data character after initiating a request. It includes the time to move the read/write head to the track (seek time) and time to rotate the platter to the sector (latency). Disk access time is always given as an average, because seek time and latency vary depending on the current position of the head and platter.

Disk vs. SSD
While access times of fast hard disks are typically from 5 to 10 milliseconds, solid state drive (SSD) access times are in the 25 to 100 microsecond range. SSDs are as much as 100 times faster because there is no mechanical seek time or latency associated with flash memory storage. However, access times for all storage types are only one metric. Channel speed (transfer rate) and caching contribute to overall storage performance. See cache, seek time and latency.

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