C64 Ultimate Toolbox
April 28, 2026 · View on GitHub
A native macOS companion app for your Commodore 64 Ultimate device — browse and manage files, write BASIC programs, view a live CRT display, and control your device from your Mac.
More screenshots: File manager · BASIC Scratchpad
Demo Video (Recorded for App Review): https://youtu.be/_2wJO2wOGm8
Features
- Two connection modes — Viewer Mode passively listens for streams; Toolbox Mode connects via REST API and FTP for full device control
- File manager — Browse, upload, download, rename, and delete files on your device. Create D64, D71, D81, and DNP disk images. Mount and unmount drives. Drag and drop from Finder.
- BASIC scratchpad — Write Commodore BASIC programs on your Mac and send them directly to your C64U. Includes sample programs to get started.
- Remote debug monitor — Interactive monitor for reading/writing memory and inspecting machine state
- Live video and audio — Real-time UDP video and audio streaming with audio balance control
- CRT shader effects — Metal-based post-processing with scanlines, bloom, phosphor afterglow, shadow masks, barrel distortion, and vignette
- 8 built-in presets — Clean, Home CRT, P3 Amber, P1 Green, Crisp, Warm Glow, Old TV, Arcade
- Custom presets — Save, modify, and delete your own CRT configurations
- Device control — Start/stop streams, load SID/MOD/PRG/CRT files, mount disk images, reset/reboot/power off, pause/resume, access the Ultimate menu
- Keyboard forwarding — Type on your Mac keyboard and have it appear on the C64, with an on-screen strip for C64-specific keys
- Auto device discovery — Automatically scans your network to find Ultimate devices with service status and password indicators
- Screenshot and video recording — Capture the CRT-processed output with synchronized audio
- Password support — Connect to password-protected devices with saved credentials
- Zero dependencies — Pure Apple frameworks (Metal, Network, AVFoundation, AppKit)
Requirements
- macOS 26 or later
- Xcode 26 (to build from source)
- A Commodore 64 Ultimate device on the local network
- Toolbox Mode requires FTP File Service and Web Remote Control Service enabled on the device
Download
- Download C64 Ultimate Toolbox v2.0 for macOS 26 and later
- Or, Purchase C64 Ultimate Toolbox on the App Store for automatic updates.
Download (For Older Macs)
Building
Open C64 Ultimate Toolbox.xcodeproj in Xcode and build. No package dependencies to resolve.
Usage
⚠️ For more detailed setup help check this: Quick Start Guide
How It Works
The app communicates with the C64U over multiple channels:
- HTTP REST API — Device info, stream control, file loading, machine control, keyboard injection (Toolbox Mode)
- FTP — File browsing, upload, download, and management (Toolbox Mode)
- UDP port 11000 — Video stream (4-bit indexed color, converted to RGBA)
- UDP port 11001 — Audio stream (16-bit stereo PCM at ~48kHz)
Video frames are assembled from UDP packets, converted from the C64's 4-bit palette to RGBA, then rendered through a Metal CRT shader pipeline at the window's native resolution.