Opcodes

Retro CPU reference

Free · In-App Purchases · Designed for iPad

Everything you wanted to know about sixteen classic CPUs. And more. Opcodes – The Retro CPU Reference The definitive opcode reference for the legendary processors that launched the personal computer revolution. Whether you're a retrocomputing enthusiast, a student of computer history, or writing code for classic hardware, Opcodes gives you everything you need - right in your hand. Twelve iconic processors covered: Intel 4004 · Intel 8008 · Intel 8080 · Intel 8085 · Intel 8088 · Zilog Z80 · Motorola 6800 · Motorola 6809 · MOS 6502 · Signetics 2650 · RCA 1802 - SC/MP For every opcode:  • Full description of what the instruction does  • Hex, octal, and decimal values  • Flags affected  • Addressing modes and cycle counts  • Assembly code examples - including loops, conditionals, and common patterns More than just opcodes:  • CPU history and historical context  • IC pinout diagrams  • Notable systems that used each chip, with memory maps • Chip variants and successors Built for exploration:  • Search for opcodes by name or category  • Sort by mnemonic, opcode byte, or category  • Filter by category, Quick Find with a colorful map • Undocumented instructions clearly marked and optionally displayed Beautifully designed:  • Clean, readable layout optimised for quick reference  • Multiple colour themes  • Full Dark Mode support From the 4-bit 4004 - the chip that started it all - to the Z80 powering countless home computers of the 1980s, Opcodes is the reference library you'll keep coming back to (if you're a bit of a nerd - no judgement!)

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This version corrects a few issues with some opcodes, but more importantly adds a top-trumps style card game for you to really nerd out about. Thanks for the idea Mr 8BitForce!

Version 1.2

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    Information

    • Provider
      • John Kennedy
    • Size
      • 23.9 MB
    • Category
      • Education
    • Compatibility
      Requires iOS 18.0 or later.
      • iPhone
        Requires iOS 18.0 or later.
      • iPad
        Requires iPadOS 18.0 or later.
      • Mac
        Requires macOS 15.0 or later and a Mac with Apple M1 chip or later.
      • Apple Vision
        Requires visionOS 2.0 or later.
    • Languages
      • English
    • Age Rating
      4+
    • In-App Purchases
      Yes
    • Copyright
      • © John Kennedy 2026
  • Developer Website
  • Privacy Policy

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