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Data Storage Units and Conversion

Aug 31, 2025

Overview

This lecture explains how data capacity is measured in computers, detailing units from bits up to petabytes and how to convert between them.

Binary Data Storage

  • Computers store all data as binary (0s and 1s), known as bits (binary digits).
  • Physical representations of binary include charged capacitors, magnetic poles, and optical pits/lans.
  • Boolean values (true/false, on/off) can be stored in a single bit.

Bits, Nibbles, and Bytes

  • A nibble is four bits, used to store simple values like a single digit on an LCD.
  • A byte consists of eight bits, capable of representing numbers, letters, or parts of images/audio.

Data Measurement Units

  • Large data amounts are measured in units like kilobyte (KB), megabyte (MB), gigabyte (GB), terabyte (TB), and petabyte (PB).
  • 1 kilobyte (KB) = 1024 bytes in binary terms, but often rounded to 1000 bytes for simplicity.
  • 1 megabyte (MB) = 1024 KB or approximately 1,000,000 bytes (decimal).
  • 1 gigabyte (GB) = 1024 MB or approximately 1,000,000,000 bytes.
  • 1 terabyte (TB) = 1024 GB or approximately 1,000,000,000,000 bytes.
  • 1 petabyte (PB) = 1024 TB or approximately 1,000,000,000,000,000 bytes.

Converting Between Units

  • To convert between units, multiply or divide by 1000 or 1024 (for binary).
  • To convert bytes to bits, multiply by 8 (since 1 byte = 8 bits).
  • Example: 1470 KB ÷ 1000 = 1.47 MB; 25 KB × 1000 = 25,000 bytes; 25,000 bytes × 8 = 200,000 bits.

Symbols and Notation

  • Units measured in bytes use uppercase letters: KB, MB, GB, TB, PB.
  • Data transfer speeds use bits, indicated by a lowercase 'b' (e.g., Mb for megabits).
  • 1 MB (megabyte) is eight times larger than 1 Mb (megabit).

Key Terms & Definitions

  • Bit — The smallest unit of data in computing, representing 0 or 1.
  • Nibble — Four bits; half of a byte.
  • Byte — Eight bits; basic unit for storing data.
  • Kilobyte (KB) — About 1,024 (or 1,000) bytes.
  • Megabyte (MB) — About 1,024 KB or 1,000,000 bytes.
  • Gigabyte (GB) — About 1,024 MB or 1,000,000,000 bytes.
  • Terabyte (TB) — About 1,024 GB or 1,000,000,000,000 bytes.
  • Petabyte (PB) — About 1,024 TB or 1,000,000,000,000,000 bytes.

Action Items / Next Steps

  • Memorize the sequence: kilo, mega, giga, tera, peta, and corresponding zeros.
  • Practice converting between units (e.g., KB to MB, MB to GB, bytes to bits).

Full transcript