emory) The main memory in a computer, smartphone or tablet. RAM is the temporary workspace where instructions are executed and data are processed. What makes RAM "random access" is its capability of reading and writing any single byte. This "byte addressability" differs from storage devices such as hard drives and solid state drives (SSDs) that read and write many bytes (sectors or pages) at one time. In addition, RAM is used as a temporary space for the software, while storage is permanent until deleted by the user. To learn how RAM is used, look at the memory examples in computer
. Also see memory
, memory module
and future memory chips
RAM Is Mostly DRAM
The most common type of RAM is dynamic RAM (DRAM). When a computer data sheet states 8GB of memory or 8GB RAM, it refers to DRAM (see dynamic RAM
). Higher-speed SRAM is also used as an internal staging area (see static RAM
Memory Is Often Not RAM!
A smartphone or tablet's specification of 16, 32, 64 or 128GB of memory does not refer to RAM; rather it is the unit's flash memory capacity for storing apps and data. The amount of internal RAM in a mobile device (typically 2GB to 6GB) is published on a tech specs Web page (see storage vs. memory
Old Fashioned RAM - 1950s
This magnetic drum was the memory in the IBM 650 computer in the mid-1950s. About 18 inches long, it held the equivalent of 20,000 bytes (20KB). That much RAM today would fit inside this letter "o" with plenty of room to spare. (Image courtesy of the Hagley Museum and Library.)
Core Memory - 1960s
Fifty Years Later
In 1967, this 30-inch-high Dataram core memory module provided a whopping 16KB for a Data General minicomputer. Women in third-world countries were hired to string the cores together using a microscope. See core storage
and early memory
Compared to the Dataram example above, two thousand times as much RAM is available in two memory modules.