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Mike Daley edited this page Sep 10, 2026 · 3 revisions

Apple //e Emulator

A cycle-accurate Apple II emulator running entirely in the browser. Built with WebAssembly (C++ backend) and WebGL rendering, it faithfully reproduces the 1.023 MHz processor, the memory architecture, all standard video modes, the Disk II controller, expansion cards, and speaker audio -- no plugins or installs required.

Two machines are modelled: the Apple //e Enhanced and the Apple II Plus. The badge in the header names the one you are running, and clicking it switches. See Machines.

Feature Highlights

  • Two machines -- Apple //e Enhanced and Apple II Plus, chosen from the header badge, each described by a profile and each remembering its own slot layout
  • Cycle-accurate CPU at 1.023 MHz -- a 65C02 on the //e, an NMOS 6502 on the II Plus, with full extended opcode support
  • 128KB memory (64KB main + 64KB auxiliary) with Language Card and double hi-res capability
  • All Apple IIe video modes -- Text, Lo-Res, Hi-Res, Double Hi-Res, Double Lo-Res, and 80-column text
  • Runs in a Web Worker -- the emulator and WASM live off the main thread, with the framebuffer and audio ring shared through SharedArrayBuffer
  • CRT shader effects -- monitor presets (composite, RGB, monochrome green/amber), scanlines with a brightness-dependent beam, selectable shadow mask geometry, phosphor glow, curvature, and analog artefacts
  • Disk II emulation with DSK, DO, PO, NIB, and WOZ format support and real-time surface visualization
  • SmartPort hard drives -- two block devices with .hdv, .po and .2mg image support
  • Expansion card system -- Mockingboard, Thunderclock Plus, Mouse Card, SmartPort, Super Serial Card, Parallel Card, Microsoft Z-80 SoftCard, No-Slot Clock
  • Game port devices -- the Apple resistive joystick and paddles, or a Sirius Joyport with two Atari-style digital sticks
  • Virtual printers -- Epson FX-80 and Apple DMP over the parallel card, ImageWriter I/II over the serial card, with a print browser
  • Audio-driven timing using Web Audio API at 48 kHz for accurate, drift-free emulation even when backgrounded
  • Save states -- autosave plus five manual slots stored in IndexedDB
  • Built-in debugger suite -- CPU debugger, memory browser, heat map, stack viewer, soft switch monitor, BASIC program viewer, rule builder, and more
  • Applesoft BASIC editor and 6502 assembler with direct memory injection
  • File Explorer for browsing DOS 3.3 and ProDOS disk contents
  • AI agent interface over MCP and AG-UI, so tools such as Claude Code can drive the emulator
  • Shareable links -- ?disk=, ?hd= and friends open the emulator with media already inserted
  • Installable PWA with light, dark, and system-follow themes

Quick Start

  1. Open the emulator in a modern browser (Chrome, Firefox, Safari, or Edge).
  2. Click the Power button in the toolbar to turn the machine on. While it is off the screen shows a NO SIGNAL message. To run something other than a //e, click the machine badge in the header first -- see Machines.
  3. If no disk is inserted, press Ctrl+Reset to reach the Applesoft BASIC prompt.
  4. To load software, open View > Disk Drives, then drag a disk image onto a drive or click to browse.
  5. Press F1 at any time for built-in documentation.

See Getting-Started for a full walkthrough.

Wiki Contents

User Guide

Page Description
Getting-Started First-time setup, powering on, inserting disks, keyboard basics, paste, and full-page mode
Machines Choosing a machine, what differs between the //e and the II Plus, ROMs, and what survives a switch
Display-Settings Monitor presets, CRT effects, analog artefacts, image controls, and rendering options
Disk-Drives Disk formats, drive UI, surface visualization, write protection, and drive sounds
SmartPort-Hard-Drives Hard drive images, the SmartPort card, and ProDOS volumes
File-Explorer Browsing DOS 3.3 and ProDOS disk contents, viewing files, and disassembly
Printers Parallel and serial printers, paper output, and the print browser
Save-States Autosave, manual save slots, and state management
Expansion-Slots Slot configuration and every available card
Input-Devices Keyboard mapping, the game port (Apple joystick or Sirius Joyport), cursor-key joystick, mouse support
Keyboard-Shortcuts Complete keyboard shortcut reference
URL-Parameters Opening the emulator with disks and hard drives already inserted

Developer Guide

Page Description
Architecture-Overview Two-layer design, the Worker split, audio-driven timing, WASM interface pattern
Worker-Architecture Web Worker isolation, WasmProxy, RPC, and the shared memory transport
CPU-Emulation 65C02 implementation, cycle accuracy, Klaus Dormann test compliance
Memory-System MMU soft switches, Language Card, bank switching, auxiliary memory
Video-Rendering Scanline rendering, WebGL pipeline, CRT shader architecture
Audio-System Speaker toggle emulation, Mockingboard synthesis, AudioWorklet pipeline
Disk-System-Internals GCR encoding, WOZ format handling, Disk II controller state machine
Debugger CPU debugger, breakpoints, rule builder, BASIC tools, memory windows
Agent-Integration MCP server, AG-UI protocol, and the frontend tool surface

Version

This wiki is not pinned to a release. Open Help > Release Notes inside the emulator for the current version and what changed in it.

Clone this wiki locally