# DEC Opcodes — Reference for DEC computers > Reference guide to DEC computer instruction sets, history, and architecture. (iPhone/iPad app by John Kennedy.) - Source: https://appshunter.io/ios/app/dec-opcodes/id6760246055 (this page in markdown: same URL + `.md`) - Developer: [John Kennedy](https://appshunter.io/developer/284943103) - Category: Education - Price: Free with in-app purchases - Rating: 5.00/5 from 3 App Store ratings - Age rating: 4+ - Requires: iOS 18.0 · 42 MB - Languages: American English - Released: 2026-03-13 - Data updated: 2026-07-22 - Monetization: free - User reviews in markdown: https://appshunter.io/ios/app/dec-opcodes/id6760246055/reviews.md ## What is DEC Opcodes? 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! ## Key features - Instruction set reference - Historical context and photos - System specifications - Interactive assembly lessons - Search and filtering - Customizable themes - Simple assembler ## Pricing and in-app purchases Base price: Free. **One-time purchases** | Purchase | Price | Type | | --- | --- | --- | | Buy Me a Coffee | $0.99 | one-time | ## Frequently asked questions about DEC Opcodes ### What DEC architectures does DEC Opcodes cover? DEC Opcodes covers five iconic DEC architectures: PDP-1 (1960), PDP-8 (1965), PDP-10 (1966), PDP-11 (1970), and VAX (1977). It provides detailed instruction sets, system specifications, and historical context for each. ### What kind of information is provided for each instruction in DEC Opcodes? For every instruction, DEC Opcodes offers a full description, octal and hex encoding, flags affected, addressing modes, word count, cycle counts, and assembly code examples. It also includes implementation notes and historical context. ### Does DEC Opcodes have interactive lessons? Yes, DEC Opcodes includes interactive lessons on assembly language and console operations, which are ideal for users with an emulator. These lessons help users understand the practical application of the instruction sets. ### What are the design features of DEC Opcodes? DEC Opcodes is beautifully designed with system-specific accent colors, five themes including Terminal green and Blinkenlights orange, and full Dark Mode support. It's built for exploration with instant search and filtering capabilities. ### Is DEC Opcodes available on multiple devices? Based on the provided data, DEC Opcodes is supported on iPhone and iPad. This makes it accessible for users on Apple's mobile and tablet platforms. ### How often is DEC Opcodes updated? The latest version of DEC Opcodes is 1.8, and it was last updated on May 26, 2026. This indicates a recent update, suggesting ongoing development and support for the application. ### What is the user sentiment for DEC Opcodes? DEC Opcodes has a perfect rating of 5.0 stars from 3 ratings. This high rating suggests very positive user sentiment and satisfaction with the app's content and functionality. ### Does DEC Opcodes have ads? No, DEC Opcodes does not contain advertisements. The application is free to download and use without any ad interruptions. ## Version history (last 5 releases) ### 1.9 — 2026-07-10 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 ### 1.8 — 2026-05-26 Hello DEC fans! In this update, I added a Glossary, so you can stop dropping DEC-terms into casual conversation. I also updated the PiDP-1 and PiDP-8 sections with some more useful little facts and tips. ### 1.7 — 2026-04-28 PDP-11 lessons, and a lot of PiDP simulation hardware help! ### 1.6 — 2026-04-14 Thanks for your support! This update includes: • New lessons on programming the PDP-11 in assembly language • More historical documents and photos • A list of real world locations to see real PDP computers ### 1.5 — 2026-04-06 Improved the PDP-1 lessons, and added new PDP-8 lesson. Highlighted notes for users of the PiDP-1 and PiDP-8. Soon you'll be ready to apply for that engineering job you always wanted (in 1960). ## More apps by John Kennedy - [Pocket Universe](https://appshunter.io/ios/app/pocket-universe/id306916838) - [What's Up?](https://appshunter.io/ios/app/whats-up/id393023070) - [Sky Time](https://appshunter.io/ios/app/sky-time/id473539346) - [Spelling Test](https://appshunter.io/ios/app/spelling-test/id478561217) - [Asstrology - Your Future Is Behind You](https://appshunter.io/ios/app/asstrology-your-future-is-behind-you/id486930635) - [Pocket Universe Classic](https://appshunter.io/ios/app/pocket-universe-classic/id567184849) All apps by John Kennedy: https://appshunter.io/developer/284943103 ## Related topics [dec opcodes](https://appshunter.io/ios/topics/dec-opcodes) · [opcodes](https://appshunter.io/ios/topics/opcodes) --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-22.*