Opcodes - retro CPU reference1.12 - App Store

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, writing code for classic hardware, or just a big old nerd - the Opcodes app gives you everything you need.

Eighteen iconic processors covered: Intel 4004 . Intel 8008 . Intel 8080 . Intel 8085 . Intel 8088 . Zilog Z80 . Motorola 6800 . Intel 8085 . Motorola 6809 . MOS 6502 . Signetics 2650 . RCA 1802 - SC/MP . Motorola 68000 . Intel 8086 . WDC 65816 . Texas Instruments TMS9900 . INMOS Transputer . ARM2

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 CPU, with memory maps and other background information.
. Chip variants and successors.
. A silly card game(!)
. Simple assembler / disassembler for many CPUs.

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.

More than microprocessors:

. Information on key support chips: video, sound, memory and more.

Cool design:

. Clean, readable layout optimised for quick reference.
. Multiple colour themes.
. Full "dark mode" support.

Everything is included with absolutely no in-app purchase required.

Recent additions:

. Quiz game - test your CPU knowledge!
. Share CPU cards - beautiful shareable images showing specs and history for any processor
. External references - curated links to community resources for all 18 CPUs
. "Opcodes display first" setting - choose whether selecting a CPU shows opcodes or info first
. Chip-maker colour themes - Zilog, MOS Tech, and Motorola replace the old themes
. Enhanced 6502 docs - JMP page boundary bug, BRK behaviour, and Read-Modify-Write quirks
. Fixed Scratchpad hang when switching tabs

Version History Improved display of flags, and source/destination order
Improved Motorola 680x0 instruction display
Added SP0256 to support chips, complete with working allophone system. Try making say rude words! 1.12 Aug 24 Updated transputer instruction list.
Some more information on Z80N. 1.11 Jul 28 Z80N instructions for Spectrum Next developers 1.10 Jul 25 Bug fixes.
New compact opcode reference chart option. 1.9 Jul 22 What's New

• Complete Motorola 680x0 family added: 68010, 68020, 68030, 68040, and 68060
• Includes FPU instructions (68881/68882 coprocessor) with the 68020
• Includes MMU instructions (PFLUSH, PTEST, PMOVE) with the 68030
• Cache control instructions (CINV, CPUSH, MOVE16) with the 68040
• Detailed historical notes tracing the architecture from 68,000 to 2.5 million transistors
• CPU Quiz now accessible from iPad sidebar
• Improved accessibility: answer feedback icons for color-blind users
• Larger tap targets on detail view buttons
• VoiceOver labels added to cross-reference navigation
• Fixed incorrect IBM PC XT data attribution under 8086
• Removed unused font asset 1.8 Jul 13 Some more facts, figures, and user interface tweaks. Plus a watch app! 1.7 Jul 8 What's New:

• Quiz game - test your CPU knowledge!
• Share CPU cards - beautiful shareable images showing specs and history for any processor
• External references - curated links to community resources for all 18 CPUs
• "Opcodes display first" setting - choose whether selecting a CPU shows opcodes or info first
• Chip-maker colour themes - Zilog, MOS Tech, and Motorola replace the old themes
• Enhanced 6502 docs - JMP page boundary bug, BRK behaviour, and Read-Modify-Write quirks
• Fixed Scratchpad hang when switching tabs 1.6.2 Jun 15 Minor fixes to a few information panels. 1.6.1 Jun 2 Added information for ARM
Improved text sizing
Fixed some factual errors 1.6 Apr 25 Added a timeline of CPUs and key computers.
Added a biography section of CPU pioneers.
Added the Transputer to the collection. 1.5 Apr 22 Updated the navigation with an old-school carousel view.
Added ASCII/PETSCII table of characters.
Added information on 25 of the most popular support chips (covering sound, I/O, video, and memory). 1.4 Apr 20 Corrected issue with missing 68000 mnemonic.
Improved view on iPad.
Disassemble code by pasting in multiple hex values for many CPUs. 1.3 Apr 6 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! 1.2 Mar 26 Improved some themes to improve visibility.
Minor tweaks and fixes. 1.1 Mar 19 1.0 Mar 18