Introduction

Every year better phones, laptops, and desktops come out. Part of what makes them better is that they hold more data.
This lesson discusses the terminology used to describe storage capacity so that you determine what you need to store your particular data and avoid tricky issues related to buying more storage.

Watch this 4-minute video explaining bits and bytes

Bits and Bytes

• Computer data is stored as 1’s and 0’s.
• The smallest piece of information = bit, one of 2 states (2¹): 1 (+) or 0 (-)
• 2 bits can store one of 4 states (2²): 00, 01, 10, or 11

8-bits in a Byte

As shown in the animated gif below: one byte has 8 bits. One byte can store 2⁸ states (i.e., 256 different states).

Bits to Yottabytes

• The lowercase b represents bits.
• The capital B represents bytes.
• The most common measurements you will see are megabytes, gigabytes, and terabytes.
  • You'll see petabytes or exabytes mentioned when people are discussing supercomputers.
  • As of 2022, you will rarely if ever hear the terms for the larger quantities.
• Assuming the commonly used base-10 system, except for the number of bits in a byte, each measure is larger than the previous by a factor of 1000.
• Download the storage size cheatsheet.
• This 5-minute video walks you through the different terms. The prefixes (e.g., kilo, mega, giga, etc.) are also used to describe speed and throughput which you will encounter in subsequent lessons.

Summary

To evaluate, purchase and understand computer systems, you must understand the terminology used to describe storage capacity.
-First, you are most likely to encounter the terms megabyte (an MP3 song is ~ 1MB per minute); gigabyte (Your smart phone storage is likely 32-256 GB); terabyte (your computer hard drive is probably 1-4 terabytes).
-Second, each level represents ~1000-fold increase (e.g., one gigabyte is 1000 megabytes). (but see the base-2 vs base-10 distinction described below).

Base-2 and Base-10

• Unfortunately, there are two systems for calculating the meaning of terms like megabyte, gigabyte, and terabyte. What I use here, and what hard drive manufacturers report is in base-10: e.g., a megabyte is one million bytes.
• However, your computer reports in base-2, e.g., a megabyte is one million 24 thousand bytes 1,024,000. This base-2 measure is sometimes called a mebibyte (but do not rely on that!).

The base-2 vs base-10 issue has resulted in confusion and lawsuits.
Obviously, the base-10 system is easier.

Watch this 4-minute overview of storage capacity:

What's Next

There is more to computer performance than the size of the storage. In subsequent lessons, you'll learn about speed, throughput, and 32-bit vs 64-bit architectures.