Opcodes vs Henge

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

THE MONUMENT • The whole circle raised: thirty sarsen uprights and their lintel ring, the five great trilithons, the bluestone circle and horseshoe, the Altar, Slaughter and Heel Stones, the Station Stone rectangle and the fifty-six Aubrey holes — every stone carrying its Petrie number. • On real ground: the terrain is Salisbury Plain's own survey data, and the ridge the midsummer sun clears is the one that actually stands there. • Weathered sarsen and Preseli bluestone, damp courses and lichen, wind moving through the grass, torchlight for the dark hours. THE CALENDAR • The Wheel of the Year: solstices, equinoxes and the four cross-quarter festivals — Imbolc, Beltane, Lughnasadh, Samhain — each landing on the instant the sun actually arrives, not on a calendar date. • Moon phases, eclipse seasons and the 18.6-year lunar standstill, solved from the real ephemeris. • A time machine from 3000 BC to AD 3000. Watch Thuban hold the celestial pole for the builders in an age when Polaris was no use to anyone. • The sky over your own longitude, or over Wiltshire. HONEST ARCHAEOLOGY Every claim the app makes about the monument carries its tier — Established, Debated, or Modern tradition — with the sources one tap away. The solstice axis is established. The equinoxes at Stonehenge are modern tradition, and the app says so. Free to explore in fifteen-minute sessions. One purchase unlocks the clock and the calendar for good — no subscription, no account, no network, and no data collected.