TRX64
What it is
TRX64 is a free, open-source runtime for cycle-accurate emulation of Commodore 64 systems and their disk drives. Written in Rust, it supports C64, Ultimate 64, and C128 selections, with PAL and NTSC C64 models documented. Its reverse-engineering tools include rewind, byte-exact reverse stepping, write tracking, traces, marks, observers, and sandboxes. You can access these capabilities through a JSON-RPC 2.0 daemon over WebSocket, the trx64cli terminal interface, or C64RE, a browser-based workbench. It supports D64 and G64 disks in 1541 drives, D81 disks in 1581 drives, cartridge types, REU, GeoRAM, and the Ultimate Command Interface. Snapshot, reverse-debug buffer, and trace formats are supported, along with conversion of VICE .vsf snapshots. Releases are available for Linux, macOS, and Windows; Homebrew installation and building from source are also documented. C64 ROMs, including the 1581 DOS ROM, are not included and must be supplied separately. The project is licensed under GPL-3.0-or-later.
For and against
For
- Free and open source under GPL-3.0-or-later
- Offers rewind and byte-exact reverse stepping
- Access through CLI, browser workbench, or JSON-RPC
- Supports D64, G64, D81, and multiple cartridge types
Against
- C64 ROMs are not included
- The 1581 DOS ROM is also not included
- Maker says real support is unavailable
The verdict
TRX64 combines machine emulation with a substantial set of reverse-engineering tools and several ways to control the runtime. It is a fit for technical users prepared to supply ROMs and work with the project’s documented interfaces.
Who it suits
TRX64 suits users working on C64 emulation and reverse engineering, especially those who want debugging tools or a programmable JSON-RPC interface. Users need to provide their own ROMs.
Plans and prices
TRX64 open-source software
GPL-3.0-or-later · C64 ROMs not included
Read 15 Oct 2026 · github.com
Free and open source
GPL-3.0-or-later · C64 ROMs are not included
Read 9 Oct 2026 · github.com
On the record
- API
- The public control interface is JSON-RPC 2.0 over WebSocket.github.com · read 15 Oct 2026
- Architecture
- The project provides a daemon and JSON-RPC API with multiple front ends sharing one emulated machine per process.github.com · read 15 Oct 2026
- Cartridges
- Supported cartridge formats include generic 8K/16K/Ultimax, Ocean, Magic Desk, EasyFlash, GMod2, GMod4, MegaByter and C64MegaCart.github.com · read 15 Oct 2026
- Checkpoints
- Full-machine checkpoints support scrubbing and read-only diffs between saved points.github.com · read 15 Oct 2026
- CLI cockpit
- trx64cli combines a terminal cockpit with an optional native emulator window.github.com · read 15 Oct 2026
- Debugging
- It provides rewind, byte-exact reverse stepping, write tracking, observers, traces, marks, and sandboxes for reverse engineering.github.com · read 9 Oct 2026
- Disk formats
- The emulator supports D64 and G64 images in 1541 drives and D81 images in 1581 drives.github.com · read 15 Oct 2026
- Documentation
- The repository includes a README, a 228-line monitor reference and a separate CLI README.github.com · read 15 Oct 2026
- Downloads
- The releases page provides prebuilt assets for Linux, macOS, and Windows, including x86_64 and arm64 builds where listed.github.com · read 9 Oct 2026
- Expansion hardware
- REU, GeoRAM and Ultimate Command Interface devices are supported.github.com · read 15 Oct 2026
- Extensibility
- Hosts can attach custom IEC devices and disk controllers through documented Rust interfaces.github.com · read 15 Oct 2026
- Headless operation
- The daemon can run headlessly and advances only when explicitly commanded.github.com · read 15 Oct 2026
- Independent report: automation
- The announcement says TRX64 can run in Docker for automated testing or locally from the command line.lemon64.com · read 15 Oct 2026
- Independent report: implementation
- A Lemon64 announcement describes TRX64 as a Rust runtime intended to be broadly comparable with VICE.lemon64.com · read 15 Oct 2026
- Independent report: input limitation
- The maker stated in the forum announcement that only keyboard and keyboard-as-joystick input were implemented, with no operating-system joystick or mouse support planned.lemon64.com · read 15 Oct 2026
- Independent report: media
- The same announcement lists D64, G64 and CRT support and describes the 1541 as a true-drive emulation.lemon64.com · read 15 Oct 2026
- Independent report: reverse buffer
- The announcement describes a default ten-second ring buffer for stepping backward and rerunning code.lemon64.com · read 15 Oct 2026
- Installation
- Prebuilt archives target macOS, Linux and Windows on x86_64 and arm64; Homebrew and cargo source builds are also documented.github.com · read 15 Oct 2026