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Definition: memory


(1) In general usage, memory often refers to any and all stored data. However, this is misleading because the basic operation of a computer is the interaction between storage drives and "random access memory" (RAM). One must be clear when discussing the mechanics of computer processing. Definition #2 below is the precise definition of memory, a key component in every computing device.

(2) Random access memory (RAM) is the temporary workspace in every computing device (desktop, laptop, smartphone, etc.). All processing takes place in memory, and the interplay between memory, storage and the CPU is how work gets done.

For desktop and laptop computers, memory capacity typically ranges from 4GB to 64GB (4-64 gigabytes), although large-scale computers can have hundreds of gigabytes, even terabytes.

Memory Does Not Remember, But Flash Does
Memory loses its content when the power is turned off, but "flash memory," the storage technology in solid state and USB drives does remember. Flash memory turned out to be a terrible name because people confuse it with random access memory (RAM). See flash memory, dynamic RAM, memory card and storage vs. memory.

All Processing Takes Place in Memory
All program execution and data processing takes place in memory. Often called "main memory," a program's instructions are copied into memory from storage (disk and solid state drives) or the network. The instructions are extracted from memory into the CPU for analysis and execution. They direct the device to input data into memory, process the data in memory and output the results from memory.

Processing Means Calculate, Compare and Copy
All data are processed (calculated, compared and copied) in memory (see 3 C's). As programs and data are written into memory, the previous contents of that space are lost. After processing, the new data are typically output (copied) from memory to the screen and back into storage.




An Electronic Checkerboard
In storage, data reside in blocks of several thousand bytes, but after the block is written into memory, any number of contiguous memory bytes can be calculated, compared and copied with any others. See byte addressable, early memory and RAM.




Memory Doesn't Remember
Memory loses its content when the power is off, so why call it memory? Because the first memory "did remember," but today's memory chips do not. However, for certain unchangeable functions, there are memory chips that do retain their content and remember (see ROM, UEFI and non-volatile memory). See storage vs. memory.

Memory Can Be Clobbered!
Memory is allocated by both the operating system and the applications but released when no longer needed. However, errant programs can fail to release memory, reducing the amount for other programs. Bugs in software can alter the wrong memory bytes creating erroneous values that can only be reset by powering the unit off and on to reboot, which clears memory. For example, rebooting from a cable box to a washing machine does the same thing: it clears memory to reset everything.

Other terms for the computer's main memory are RAM, primary storage and read/write memory. Earlier terms were core and core storage. See dynamic RAM, static RAM, core storage and memory module.




Clogged TV Memory
This message appeared on an LG OLED TV. The specific app is not mentioned but apparently referred to one of the streaming service apps. Memory can get overloaded and corrupted at any time in any computing device. Although Xfinity, the cable TV provider in this example, routinely updates the program guides and software in the customer's cable box, this message was displayed for the first time after seven years of daily TV use. See set-top box.