Stefan ArentzandClaude Fable 5
328671353d
New ewm/src/hdd.rs: a virtual hard disk controller card, the device every emulator adds for 32MB .hdv images. A 256-byte hand-assembled firmware ROM at $C700 (assembly listing in comments, embedded like DSK_ROM) speaks the ProDOS block-driver protocol — command/unit/buffer/ block in $42-$47, entry published at $C7FF — and pumps data byte by byte through magic I/O ports at $C0F0-$C0FF, so blocks move over the normal bus and the Device never touches machine RAM. The Autostart ROM's slot scan (verified in 341-0020: it checks $Cn01/03/05/07 = $20/$00/$03/$3C, slots 7 down to 1) finds the card before the slot 6 Disk II, so 'ewm two --hdd image.hdv' boots straight from the hard drive; without --hdd the card does not exist and floppy boot is unchanged. Writes persist: committed blocks go to the in-memory image and are flushed to the .hdv file, so Total Replay preferences and high scores survive restarts. Read-only files mount with writes failing as WRITE PROTECTED ($2B). Tests: port protocol, write persistence to the file, the firmware driver called ProDOS-style (READ/WRITE/STATUS via JSR $C740), and a full boot from a synthetic image through the Autostart scan. Total Replay v6.0.1 verified booting to its menu (472 games detected). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Emulated Woz Machine
EWM is an emulator for the machines Steve Wozniak built: the Apple 1, the Replica 1 and the Apple ][+. It started life many years ago as a tiny 6502 emulator written between christmas and new year, and has since grown into a full emulator with Disk II support, graphics, and sound.
Note: EWM is a hobby project and still under development. Things may be incomplete, quirky, or broken — bug reports and pull requests are welcome. See REWRITE.md for the project's verification gates and a list of known quirks and deliberate divergences.
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![Apple ][+ booting DOS 3.3](/Apple-2-Tools/ewm/src/branch/hdd/screenshots/Screenshot%202026-07-05%20at%2011.30.59.png) |
| Replica 1 — KRUSADER 1.3 from the Woz Monitor | Apple ][+ — booting the DOS 3.3 sample programs disk |
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| Frogger in color hi-res graphics | Bandits by Sirius Software |
What's emulated
- Apple 1 — 6502, 8KB RAM, Woz Monitor
- Replica 1 — 65C02, 32KB RAM, KRUSADER assembler ROM
- Apple ][+ — 6502, 48KB RAM, Apple Language Card, Disk II with two drives, a slot 7 hard drive for 32MB ProDOS block images (boots Total Replay!), 40-column text, low-resolution and high-resolution graphics (color or green monochrome), speaker sound, joystick paddles and buttons
Requirements
- A Rust toolchain (the pinned version is in
rust-toolchain.toml; rustup picks it up automatically) - SDL2 —
brew install sdl2on macOS,apt install libsdl2-devon Debian/Ubuntu
Building
cargo build --release
Running
Running EWM with no arguments opens the bootloader, a menu where keys 1/2/3 select the machine to start:
cargo run --release
Or start a machine directly:
# Apple ][+ with color graphics and the DOS 3.3 sample programs disk
cargo run --release -- two --color --drive1 disks/DOS33-SamplePrograms.dsk
# Apple ][+ booting Total Replay from a ProDOS hard drive image
cargo run --release -- two --color --hdd "disks/Total Replay v6.0.1.hdv"
# Replica 1 (Woz Monitor + KRUSADER)
cargo run --release -- one --model replica1
# Classic Apple 1
cargo run --release -- one --model apple1
Each subcommand accepts --help for all options. Useful keys while the
emulator runs:
| Key | Action |
|---|---|
| Cmd-Esc | Reset the machine |
| Cmd-Return | Toggle fullscreen |
| Cmd-P | Pause (Apple ][+) |
| Cmd-I | Toggle the status bar with drive lights (Apple ][+) |
There are also headless terminal consoles, handy for quick experiments without a window:
cargo run -p ewm --example one # Woz Monitor
cargo run -p ewm --example two -- disks/DOS33-SystemMaster.dsk # AppleSoft / DOS 3.3
Testing
cargo test
This runs the full verification suite: the Klaus Dormann 6502 and 65C02
functional tests, golden instruction traces, headless machine boot tests,
a complete DOS 3.3 boot with CATALOG, and a golden screenshot comparison.
The cc65 assembly sources under tests/ are manual test programs for the
machines themselves and are not part of the automated suite.
History
EWM was originally written in C and was ported to Rust in 2026 — the full phase-by-phase plan, parity checklist, and benchmark numbers are preserved in REWRITE.md. The original C implementation lives in the git history.
License
MIT, as declared in Cargo.toml (the same license the original C carried
in its source headers).