What is the difference between RAM and memory?

When people talk about computer RAM or memory it is sometimes hard to discover what they mean. This is because sometimes the term memory is used to refer to a computer’s work memory and sometimes used to refer to other types of memory. In this post I have taken the effort to create more clarity about the difference between RAM and other types of memory.

RAM is an abbreviation for random-access memory. This is a type of so called volatile memory that stores instructions for frequently used programs to speed up computer usage. A characteristic of volatile memory is that the information that is stored is lost once it no longer receives energy.

As an example, when you are playing a PC game your RAM will be able to store specific instructions to streamline the information that is being processed. Once the game is completed and your PC is shut down this information is lost. RAM is therefore also referred to as a system’s short term memory. A random-access memory device’s multiplexing and demultiplexing circuitry connect data lines to addressed storage in such a way that reading or writing entries occurs nearly instantaneous.

On the other hand there is also non-volatile memory, which does not require energy to maintain stored information. One example of non-volatile memory is direct-access data storage memory, this includes media such as hard disks, CD-RWs, DVD-RWs and the older drum memory. The time to read and write data items using these types of memory varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement.

These earlier mentioned types of non-volatile memory are specifically aimed at storing data for longer amounts of time and for storing information that is not required on a regular basis. In general these types of storage memory also have a much higher storage capacity compared to RAM.

Modern desktop computers and laptops are frequently equipped with SSDs or solid state drives. Although they do not come with spinning components, they do maintain stored information even after losing its power supply. This means that SSDs fall under the category of non-volatile memory as well, or more specifically NAND-based flash memory.