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Core Computing Units Overview

Jun 21, 2025

Overview

This lecture explains the core units of measurement in computing, including data size, transfer speed, frequency, storage performance, and power, as required for the CompTIA Tech Plus exam.

Data Size Units

  • Bit (binary digit) is the smallest data unit—value is 0 or 1.
  • Byte consists of 8 bits, commonly represents one character.
  • Kilobyte (KB) = 1,024 bytes, but often rounded to 1,000 bytes.
  • Megabyte (MB) = 1,024 KB or ~1 million bytes.
  • Gigabyte (GB) = 1,024 MB or ~1 billion bytes.
  • Terabyte (TB) = 1,024 GB or ~1 trillion bytes.
  • Petabyte (PB) = 1,024 TB or ~1 quadrillion bytes.

Data Transfer Units

  • Bits per second (bps) measures data transfer speed; often used for internet speeds.
  • Kilobits per second (Kbps) = 1,000 bps; used in older internet connections.
  • Megabits per second (Mbps) = 1,000 Kbps or 1 million bps; standard for most broadband.
  • Gigabits per second (Gbps) = 1,000 Mbps or 1 billion bps; used in fiber and enterprise networks.
  • Terabytes per second (TBps) = 8 terabits per second or 1,000 gigabytes per second; found in supercomputing.

Frequency and Processor Speed

  • Hertz (Hz) measures frequency or cycles per second.
  • Kilohertz (KHz) = 1,000 Hz, megahertz (MHz) = 1 million Hz, gigahertz (GHz) = 1 billion Hz.
  • Modern CPU speeds are measured in GHz.

Storage Performance

  • Revolutions per minute (RPM) measures how fast a hard drive’s platters spin.
  • Common HDD speeds: 5,400 RPM and 7,200 RPM; SSDs do not use RPM.

Power Consumption

  • Watt (W) measures power usage in computing devices.
  • Laptops typically use 30–90 watts; gaming desktops may use over 500 watts.

Key Terms & Definitions

  • Bit — Smallest unit of digital data; value of 0 or 1.
  • Byte — Group of 8 bits; represents one character.
  • Kilobyte (KB) — 1,024 bytes (often rounded to 1,000).
  • Megabyte (MB) — 1,024 KB.
  • Gigabyte (GB) — 1,024 MB.
  • Terabyte (TB) — 1,024 GB.
  • Petabyte (PB) — 1,024 TB.
  • Hertz (Hz) — Frequency, cycles per second.
  • Revolutions per Minute (RPM) — Rotational speed of a hard disk.
  • Watt (W) — Power consumption rate.

Action Items / Next Steps

  • Review units and conversions between bits, bytes, and their multiples.
  • Practice differentiating between MBps (megabytes per second) and Mbps (megabits per second).
  • Prepare for questions comparing units (e.g., storage size, transfer speed, processor speed) for the exam.

Full transcript