Computer Memory

In the simplest terms, computer memory is an electronic mechanism that has the ability to store and retrieve data. The smallest amount of data that can be stored is 1 bit, which can be represented by either a 1 or a 0 in memory. When you put 4 bits together, it is called a nibble, which can represent values from 0000 to –1111. There are exactly 16 binary values, ranging from 0 to 15, in decimal format. When you put two nibbles, or 8 bits, together, you get a byte, which can represent values from 0 to (2⁸ – 1), or 0 to 255 in decimal. When you put 2 bytes together, you get a word, which can represent values from 0 to (2¹⁶ – 1), or 0 to 65,535 in decimal. Continuing to piece data together, if you put two words together, you get a double word, or DWORD, which can represent values from 0 to (2³² – 1), or 0 to 4,294,967,295 in decimal.

There are many types of computer memory; we will focus on random access memory (RAM) and registers. Registers are special forms of memory embedded within processors, which will be discussed later in this chapter in the “Registers” section.