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How does a computer store data?

Before you look at how a computer processor works, you need to look at how a computer can store data. Here, we outline how this works. 

Before you look at how a computer processor works, you need to look at how a computer can store data. Here, we outline how this works.

Image showing a memory cell. Current flows through a transistor onto one side of a capacitor, with the other side of the capacitor connected to ground.

Above is a diagram of a memory cell, consisting of a transistor and a capacitor (a component that can hold an electric charge). The transistor allows the capacitor to be charged. A fully charged capacitor would represent a 1, and a discharged capacitor would represent 0.

These memory cells can be arranged in a grid. For example, in the diagram below, they are arranged in a grid that is eight memory cells across. Any of these cells can be accessed, and a 1 or 0 written into the memory cell.

Animation showing the memory cell from the previous image zooming backwards to take up 1 slot in a 4x4 grid of identical cells. This then zooms back to slot into an 8x8 grid.

Because any particular memory cell can be accessed at random, this is called Random Access Memory, or RAM for short.

An 8x8 array of blue boxes representing memory cells. A black 1 or 0 is visible on each cell, and these are all changing independently.

There are actually many different types of memory cell, and many different types of RAM. However, you don’t need to worry about the details, so you can think of RAM as a table of numbers.

A table with two columns, labelled "Address" and "Data". The addresses count up from 0 to 13, while each piece of data is an 8-digit binary number.

You can use addresses to tell you which memory cells a piece of data is written into. The data itself is the content of those cells. Depending on circumstances, it will be an 8-bit, 16-bit, 32-bit, or even 64-bit number (so each address corresponds to eight single-bit memory cells, or to 16 single-bit cells, etc.)

And just like with transistors in our CPUs, you can get billions of memory cells in a RAM module, such as the one below.

A picture of a RAM module

Most desktop and laptop computers need one or more RAM modules attached to the motherboard to work. Computers will generally come with these already in place, but you may also be able to increase the RAM size by replacing this module or by placing additional RAM modules in extra slots on your motherboard.

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How Computers Work: Demystifying Computation

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