Opcodes
Retro CPU reference
About
This app provides a comprehensive reference for retro CPU opcodes, including detailed descriptions, assembly examples, and historical context. It covers eighteen iconic processors and offers features like search, sorting, and filtering for easy exploration of historical computing information.
What's New in Opcodes
1.9
July 22, 2026
Bug fixes. New compact opcode reference chart option.
In-App Purchases
$0.99
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FAQ
What processors does Opcodes cover?
Opcodes covers eighteen iconic processors, including the Intel 4004, 8080, 8085, 8088, Zilog Z80, Motorola 6800, 6809, MOS 6502, and ARM2, among others. This extensive list ensures comprehensive coverage for retrocomputing enthusiasts.
What kind of information is provided for each opcode?
For every opcode, Opcodes provides a full description of the instruction's function, its hex, octal, and decimal values, the flags it affects, addressing modes, and cycle counts. It also includes assembly code examples for common patterns and logic.
Does Opcodes offer any historical context beyond just opcodes?
Yes, Opcodes goes beyond just opcodes by including CPU history and historical context, IC pinout diagrams, notable systems that used each chip with memory maps, and information on chip variants and successors. It also features a card game and a simple assembler/disassembler.
How can I find specific opcodes or information within Opcodes?
Opcodes is built for exploration with features like searching for opcodes by name or category, sorting by mnemonic, opcode byte, or category, and filtering by category. A colorful Quick Find map is also available for easy navigation.
Is Opcodes available on multiple devices?
Yes, Opcodes is supported on both iPhone and iPad, making it accessible to a wide range of users interested in retro computing. The clean design is optimized for quick reference on these devices.
How often is Opcodes updated?
The latest version of Opcodes is 1.6.1, and it was last updated on June 2, 2026. This indicates a commitment to maintaining and improving the reference material.
What is the age rating for Opcodes?
Opcodes has an age rating of 4+, making it suitable for a broad audience interested in learning about computer history. The app's educational content is accessible to younger users as well.
Does Opcodes have ads?
No, Opcodes does not contain advertisements. The app is completely free to use and includes all its features without any in-app purchases or ad interruptions.