💾

Data Storage Units and Conversion

Aug 31, 2025

Overview

This lecture covers how data capacity is measured in computer systems, focusing on bits, bytes, and larger units, as well as how to convert between these units.

Binary Storage Basics

  • All computer data is stored in binary: zeros (0) and ones (1).
  • Different technologies represent binary states, such as electrical charge, magnetism, or physical marks.
  • A single binary digit is called a bit.

Units of Data Storage

  • 1 bit can store a Boolean value (true/false, on/off).
  • Multiple bits are combined to represent complex data (e.g., 4 bits = 1 nibble).
  • 8 bits make 1 byte.
  • A byte can represent a character, part of a number, image, or sound.

Hierarchy of Data Units

  • 1 kilobyte (KB) = 1024 bytes (binary) or ≈1000 bytes (decimal, simplified).
  • 1 megabyte (MB) = 1024 KB or ≈1,000,000 bytes.
  • 1 gigabyte (GB) = 1024 MB or ≈1,000,000,000 bytes.
  • 1 terabyte (TB) = 1024 GB or ≈1,000,000,000,000 bytes.
  • 1 petabyte (PB) = 1024 TB or ≈1,000,000,000,000,000 bytes.
  • For exams, remember the order: kilo, mega, giga, tera, peta—each adds three zeros in decimal.

Byte and Bit Conversions

  • To convert between units, multiply or divide by 1000 (decimal) or 1024 (binary).
  • 1 byte = 8 bits; to convert bytes to bits, multiply by 8.

Example Conversions

  • 1470 KB = 1.47 MB (divide by 1000).
  • 740 KB = 0.74 MB.
  • 25 KB = 25,000 bytes; 25,000 bytes = 200,000 bits.

Symbols and Notation

  • KB, MB, GB, TB, PB use capital 'B' for bytes.
  • Network speeds use lowercase 'b' for bits (e.g., Mb/s).
  • 1 MB (megabyte) is eight times larger than 1 Mb (megabit).

Key Terms & Definitions

  • Bit — the smallest unit of data (binary digit: 0 or 1).
  • Byte — 8 bits.
  • Nibble — 4 bits.
  • Kilobyte (KB) — ≈1000 or 1024 bytes.
  • Megabyte (MB) — ≈1,000,000 or 1,048,576 bytes.
  • Gigabyte (GB) — ≈1,000,000,000 bytes.
  • Terabyte (TB) — ≈1,000,000,000,000 bytes.
  • Petabyte (PB) — ≈1,000,000,000,000,000 bytes.

Action Items / Next Steps

  • Memorize the order: kilo, mega, giga, tera, peta.
  • Practice converting between bits, bytes, and higher units.
  • Learn symbols for bits (lowercase b) and bytes (uppercase B).

Full transcript