DEC Opcodes

Reference for DEC computers

Free · In-App Purchases · Designed for iPad. Not verified for macOS.

Big iron in your pocket! All the information you need on DEC's series of influential computers, including coding lessons and real-world locations to see them for real. Dec Opcodes – DEC Architecture Reference Before the microprocessor, there was DEC. The minicomputers built by Digital Equipment Corporation didn't just advance computing - they defined it. Unix was born on a PDP-7. Spacewar! ran on a PDP-1. The field of Artificial Intelligence was born on the PDP-10. The VAX powered universities and research labs worldwide for a generation. DecOpcodes puts the complete instruction sets of these legendary machines in your pocket. Five iconic architectures covered: PDP-1 (1960) · PDP-8 (1965) · PDP-10 (1966) · PDP-11 (1970) · VAX (1977) For every instruction:  • Full description of what the instruction does  • Octal and hex encoding  • Flags affected  • Addressing modes, word count, and cycle counts  • Assembly code examples and implementation notes But there is a lot more than just dry opcodes:  • Complete system specifications and register architecture  • Historical context and cultural impact  • Archival photographs - front panels, system cabinets, and more  • Notable installations and the systems they powered  • Architecture variants and successors • Interactive lessons on assembly language and console operations (ideal if you have an PiDP emulator) Built for exploration:  • Search across all systems instantly • A simple assembler for PDP-1, -8 and -11 code • Filter by instruction category  • Sort alphabetically or by category • Favorite instructions for quick reference Beautifully designed:  • System-specific accent colours  • Five themes including Terminal green and Blinkenlights orange  • Full Dark Mode support From the 18-bit simplicity of the PDP-1 to the 32-bit sophistication of the VAX, DecOpcodes is a fascinating and interactive journey through the machines that made modern computing possible. All features are free and unlocked. If you like the app you can always leave a nice review or tip the developer!

Ratings & Reviews

  • This app has not received enough ratings or reviews to display an overview.

What's New in v1.9 • DEC Glossary - Searchable guide to 45+ terms across buses, memory, storage, I/O, processors, software, and DEC culture • PDP-11 instructions added - MFPI, MFPD, MTPI, MTPD (previous-space memory access) and SPL (set priority level) • Memory Maps corrected - Separate PDP-11/45 (256KB) and PDP-11/70 (4MB) layouts; KW11-L and KW11-P clocks added to I/O page; byte units for PDP-11 and VAX • Official DEC handbooks linked - Architecture Handbook PDFs from bitsavers for all five systems in Programming Resources • System landing page setting - Choose whether tapping a system opens the instruction list or the system info page • PiDP-8 Quick Start expanded - OS/8 first commands, paper tape bootstrap sequence, Spacewar! controls, TSS/8 multi-user login, USB storage guide • PDP-1 toggle programs fixed - Correct memory addresses and proper ADD-based counting loop • Dynamic Type support - All sidebar and card text now scales with your preferred font size • Accessibility improved - Better VoiceOver labels and touch targets throughout • Faster launch - Removed artificial splash screen delay

Version 1.9

The developer, John Kennedy, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

  • Data Not Collected

    The developer does not collect any data from this app.

    Privacy practices may vary based, for example, on the features you use or your age. Learn More

    Accessibility

    The developer has not yet indicated which accessibility features this app supports. Learn More

    Information

    Provider
    • John Kennedy
    Size
    • 44.5 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
    • © 2026 John Kennedy
  • Developer Website
  • Privacy Policy

    • More by John Kennedy

    You Might Also Like