Field Guide · concept

Also known as: non-volatile memory

Volatile memory loses its contents the moment power is removed, while non-volatile memory keeps them — a distinction that shapes how every computer divides fast working memory from lasting storage.12

Overview

RAM is the archetypal volatile memory: it is fast and freely rewritable, which makes it ideal as the place a running program keeps its data, but everything in it vanishes at power-off. Non-volatile memory — flash, ROM, hard disks, tape — gives up some speed or flexibility in exchange for retaining data without power. Cache memory is also volatile. The trade-off is fundamental: the fastest memories tend to be volatile, and persistence tends to cost speed or write endurance.

Where it fits

This split is why a computer cannot simply use one kind of memory for everything. Volatile RAM holds the working state of the operating system and applications; non-volatile storage holds files and programs between sessions, which is why work must be saved to disk to survive a reboot. The memory hierarchy arranges these layers by speed and cost. For GopherTrunk, decoded frames live briefly in volatile RAM as they are processed, then are written to non-volatile storage so the log survives a restart or power cut at the antenna site.

Sources

  1. Volatile memory — Wikipedia, on memory that requires power to retain data. ↩

  2. Non-volatile memory — Wikipedia, on memory that retains data without power. ↩

See also