webR vs DEC Opcodes
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
webR
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The smallest app that runs language R without using an external web server. It is less than 40 MB in size!
DEC Opcodes
Explore the instruction sets of legendary DEC computers like the PDP and VAX. This app provides detailed information on each instruction, historical context, and interactive lessons. Discover the machines that shaped modern computing.
- Instruction set reference
- Historical context and photos
- System specifications
- Interactive assembly lessons
- Search and filtering
- Customizable themes
- Simple assembler
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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!
Screenshots
Verdict
The clearest difference is in-app purchases: webR at none against DEC Opcodes's 1. webR also leads on iOS requirement (14.0 vs 18.0). DEC Opcodes's advantage is update cadence (every 8 days vs monthly). On price, ads and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. DEC Opcodes sells 1 one-off in-app purchase. webR asks for nothing beyond the download.
webR ships an update monthly, DEC Opcodes every 8 days. The most recent releases landed on September 17, 2026 and September 20, 2026 respectively.
| Parameter | webR | DEC Opcodes |
|---|---|---|
| Price | Free | Free |
| Rating | — | 5.0 (3 ratings) — better |
| Number of ratings | — | 3 — better |
| Update frequency | Monthly | Every 8 days — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | — | Free |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 14.0 — better | 18.0 |
| Further details — not scored | ||
| Size | 32 MB | 42 MB |
| Age rating | 17+ | 4+ |
| Developer | Luis Acevedo-Arreguin | John Kennedy |
In-app purchases
webR
No in-app purchases
DEC Opcodes
- Buy Me a Coffee$0.99









