C64AI brings the spirit of modern artificial intelligence to the legendary Commodore 64 — without sacrificing the authentic retro experience. While chatting with an AI on real 8-bit hardware, you can simultaneously enjoy classic SID music, just like the golden days of home computing. (https://www.youtube.com/watch?v=YmIsD-U5dIw)
Chat interaction and music playback run side by side, smoothly and continuously, proving that the C64 still has plenty of magic left under the hood.
With built-in support for the Commodore 1351 mouse, navigating menus and interacting with the interface feels natural and responsive. Prefer the keyboard, just like back in the day? No problem — the application offers full keyboard control, with all essential functions accessible through carefully designed key bindings.
Whether you are running:
- Original Commodore 64 hardware
- Your favorite emulator (Tested with VICE 3.9)
- A setup with or without a mouse
C64AI adapts seamlessly and delivers a true retro computing experience — enhanced with a modern twist. Power up your C64, turn up the SID, and experience what 8-bit computing can still achieve.
The project supports three different usage scenarios, covering both emulation and real hardware setups.
In the first scenario, C64AI runs on Windows and Linux systems via the VICE emulator, offering an easy and accessible way to get started.
The second scenario uses a real Commodore 64 or Commodore 128 connected through custom hardware integrated with a Raspberry Pi Zero 2, combining classic 8-bit systems with modern embedded technology.
In the third scenario, a real Commodore 64 or Commodore 128 operates alongside any 64-bit computer with an installed operating system and USB serial port support, enabling seamless communication between vintage and modern platforms.
The C64AI project enables serial communication between Commodore 64 and Commodore 128 systems and an external computer via the User Port interface, using an FT232RL-based USB–TTL converter. This architecture supports bidirectional data transfer, allowing real-time interaction between classic 8-bit hardware and modern systems.
The Raspberry Pi Zero 2 is used as the reference platform due to its compact form factor, low power consumption, and Linux-based operating system support. The required hardware connections are clearly illustrated in the schematic provided below.
Alternatively, the same communication infrastructure can be established by connecting the FT232RL module via a standard USB interface to any computer running Windows, Linux, or macOS, making the system flexible across a wide range of modern platforms.
The figure illustrates the hardware connection architecture of the C64AI system in detail. The Commodore 64 User Port interface is directly connected to an FT232RL-based USB–TTL converter module. Within this setup, the A pin of the User Port is used as the ground (GND) reference, while the B and C pins are configured as transmit (TX) data lines connected to the FT232RL module. The receive (RX) data line is routed from the corresponding User Port pin to the RX input of the FT232RL module. This configuration enables reliable serial communication between the Commodore 64 and the external system.
The FT232RL module is connected to a Raspberry Pi Zero 2 via a USB OTG cable, providing the serial data link. Power for the Raspberry Pi Zero 2 is supplied independently through its secondary USB port, separate from the FT232RL connection. This separation of power and data paths improves overall system stability. The Raspberry Pi Zero 2 operates from a microSD card containing the C64AI software and serves as the primary control unit of the system.
The GPIO pins on the Raspberry Pi Zero 2 are configured for optional user interaction and system control. One designated GPIO pin is connected to a push-button input. When triggered, the button initiates a safe operating system–level shutdown, ensuring that the system powers down cleanly.
This mechanism is specifically intended to prevent microSD card data corruption and file system errors, allowing the system to shut down safely without risking data integrity.
In addition, another GPIO pin is connected to an LED through a series resistor, providing visual feedback on the system’s operational status. A 67 kΩ current-limiting resistor is used in the LED circuit to ensure safe operation.
Together, this hardware and control architecture delivers a reliable, bidirectional serial communication infrastructure between the Commodore 64 and the Raspberry Pi Zero 2, while also incorporating practical safeguards to maintain system stability and data integrity.
For use on any 64-bit computer running Windows, Linux, or macOS via a USB connection, refer to the figure below.
The FT232RL module is widely supported and is typically recognized without issues by modern operating systems, requiring little to no manual configuration.
| Operating System | Driver Support | Detected Port |
|---|---|---|
| Windows 10/11 | Automatic | COMx |
| Linux | Built-in kernel driver | /dev/ttyUSBx |
| macOS | Automatic | /dev/tty.usbserial-* |
Thanks to this broad native support, the FT232RL provides a simple and reliable bridge between vintage Commodore hardware and modern desktop systems, keeping setup time minimal and the retro experience uninterrupted.
If working with real hardware is not desired, C64AI can be executed using virtual serial ports on Windows or Linux, in combination with the VICE emulator.
The following three files are required:
.envc64aiserver(GCC is required to build)ask2ai(Deno is required to build: https://deno.com/)
To power up the AI core correctly, you must configure the .env file with your Gemini settings.
This file defines which Gemini model is used, how responses are generated, and the language of interaction. Without it, the system won’t know who it is or how to talk.
Make sure your .env file includes the following entries:
GEMINI_API_KEY=your_api_key_here
GEMINI_MODEL=gemini-2.5-flash
GEMINI_INITIAL_INSTRUCTION=Provide text-based responses. Keep the conversation context in mind. Responses should be neither too short nor too long.
LANGUAGE=ENGLISH- GEMINI_API_KEY Your personal key to access the Gemini API
- GEMINI_MODEL The selected Gemini model (fast, lightweight, and perfect for retro systems)
- GEMINI_INITIAL_INSTRUCTION Defines the AI’s response style and context awareness
- LANGUAGE Sets the conversation language
To obtain your API key and select a Gemini model, visit the official Gemini dashboard at https://aistudio.google.com/apps. This site lets you register, manage access credentials, and choose the model that best suits your needs before adding them to your .env configuration.
A guide for creating virtual serial port drivers on Windows is available at: https://vovsoft.com/blog/how-to-sniff-serial-port-communication
After creating the virtual ports, open VICE Settings → Peripheral Devices → RS232 and enable:
- Enable userport RS232 emulation
- Set Serial1 and Serial2 to 2400 BAUD
- Enter the COM port names created in Windows Device Manager for Serial1 and Serial2
VICE Settings
.\c64aiserver.exe
Usage: c64aiserver.exe <port_name>
Windows: c64aiserver.exe COM3
Linux : c64aiserver.exe /dev/ttyUSB0If the virtual serial port is COM6, run:
.\c64aiserver.exe com6
com6 port opened (2400 baud).
C64AI Server started. Waiting for commands from C64…On Linux, virtual serial ports can be created easily using socat and used with VICE.
Create paired virtual serial ports:
socat -d -d pty,link=/tmp/ttyS10,raw,echo=0 pty,link=/tmp/ttyS11,raw,echo=0Example output:
2025/12/07 16:56:59 socat[12620] N PTY is /dev/pts/5
2025/12/07 16:56:59 socat[12620] N PTY is /dev/pts/7
2025/12/07 16:56:59 socat[12620] N starting data transfer loop with FDs [5,5] and [7,7]Run the C64AI server:
sudo ./c64aiserver /dev/pts/7
/dev/pts/7 port opened (2400 baud).
C64AI Server started. Waiting for commands from C64...In VICE → Userport RS232 Settings:
- Enable userport RS232 emulation
- Device: Serial1
- Baud rate: 2400
- Serial1 device:
/dev/pts/5(or/dev/ttyS11)
This setup allows C64AI to run entirely in an emulated environment, delivering a smooth retro experience without requiring physical Commodore hardware—perfect for development, testing, and experimentation.
Once all hardware connections have been completed, the system should be connected to the C64/C128 User Port. When using a Raspberry Pi Zero 2, the prepared system image must first be written to a microSD card and inserted into the device. (See the SD Card Installation Guide.md document)
The Raspberry Pi Zero 2 should be powered on using an external power source before starting the Commodore 64. After the Raspberry Pi is fully operational, the Commodore 64 can be powered on.
If the system is being started for the first time, the C64AISETUP application must be loaded and executed on the C64 side to perform the initial configuration.
LOAD "C64AISETUP",8,1
C64AISETUP
Once the application is launched, on-screen guidance and explanatory prompts will be displayed.
If the operating system running on the Raspberry Pi Zero 2 is unable to connect to a predefined Wi-Fi SSID, it automatically starts a built-in web server. In this case, a client device should connect to the wireless network named C64AI-Setup using the password 12345678.
After connecting to the network, the configuration interface can be accessed either by scanning the QR code displayed on the screen or by entering the following address into a web browser:
http://10.42.0.1
Configuration interface
This setup process allows the system to be configured quickly and intuitively, keeping the classic C64 experience intact while leveraging modern connectivity.
This process is designed to complete the system’s network configuration in a secure and controlled manner. During the same stage, the API key required for accessing the Gemini AI service, along with the configuration parameters of the selected model, are defined.
To enable the Raspberry Pi Zero 2 to access the internet over the local network and activate the AI-driven chat functionality, the corresponding Wi-Fi network credentials must be entered accurately and completely.
When the Save & Connect button is pressed, the Raspberry Pi Zero 2 system is automatically rebooted. Once this process is complete, the Commodore 64 should be powered off and then turned on again.
Next, the C64CHAT application must be loaded using the command below. Due to potential compatibility issues with certain cartridge hardware, it is recommended that no cartridge be inserted while running the application. Although the loading process may appear to start, the application may fail to operate correctly if a cartridge is present.
LOAD "C64CHAT",8,1
C64CHAT loading command
When using a floppy disk or an SD2IEC device, the file c64-UP2400.ser (https://github.com/nanoflite/c64-up2400-cc65) (See the where is c64-up2400.ser.md document) must be present in the corresponding directory. This file is a mandatory component required to establish serial communication with the correct parameters. In addition, the file HELP.PRG must also be available.
Welcome Screen
Entering a question in the chat textbox
After entering the text, press RETURN or click the UP ARROW button with the mouse. CURSOR LEFT and CURSOR RIGHT can be used to navigate between words inside the textbox.
The question is being sent to the AI
Receiving the AI response
First page of the AI response
Page navigation is performed using CURSOR UP or CURSOR DOWN. Page navigation is not limited to keys only — pages can also be switched by clicking the < and > symbols next to the page numbers using a 1351 mouse.
Accessing the SID file list by clicking the music note icon
The F2 key or entering the command /sidfiles in the textbox provides the same functionality.
Switching between available disk devices
By clicking the Device field or pressing F4, available disk drives are cycled and SID files are listed if present. Page navigation is done using CURSOR UP or CURSOR DOWN.
Loading and playing a SID file
To load and play a file, simply click on the desired SID filename. Alternatively, the command /load sidfilename.sid can be used.
Viewing SID file information
Press F3 to display SID details. If the SID contains multiple tracks, F5 is used to switch between songs.
Help
The /help command displays the help screen and can also be accessed by pressing the F1 key or clicking the ? icon. The content of the HELP.PRG file located on the same drive as the application is displayed.
To start a new conversation and clear the chat history, use the /new command or click the icon located in the top-right corner of the screen.
If you want to receive AI responses in a specific language, use the /lang command. Regardless of the language used for text input, the AI response will be generated in the language specified by this command.
Examples:
/lang=english
/lang=german
/lang=turkce
/lang=<write your own language>To change the page color, press the F7 key or click the icon located below the New Chat symbol.
SID playback can be controlled using the PLAY and PAUSE icons, or by entering the /play or /pause commands.
To re-display the most recent AI response, press F6. In cases where a response cannot be received due to connection interruptions or temporary AI unavailability, press F8 to resend the last prompt instead of retyping it.
To ensure seamless SID music playback within the application, certain technical constraints must be satisfied. Specifically, the SID file’s load address is expected to be $1000, and the data offset must fall within the $1000–$3000 range. This corresponds to an approximate file size of 8 KB, or 32 disk blocks.
SID files that do not meet these requirements should be made compatible using the sidreloc tool to perform memory relocation. Failure to comply with these constraints may prevent the application from functioning correctly.
As an example, consider a SID file selected from the HVSC archive:
MUSICIANS/C/Cadaver/Metal\_Warrior\_2.sid
When inspecting the SID tune properties using Sidplay2/w (Win32 version 2.6), the data size is reported as 7812 bytes. For C64AI, the maximum supported size is 8192 bytes, meaning this file meets the size requirement.
However, the load range of the SID file is $8100–$9F83. If the load address had started at $1000, the file could have been used without relocation. In its current form, the SID file must be relocated before it can be used with C64AI.
SID Tune Properties
Now, to relocate this SID file to address $1000, use the sidreloc tool from the terminal. The first argument must be the original SID file, and the second argument must be the name of the relocated SID file.
The relocated SID filename must not exceed 16 characters and must use the .SID file extension.
sidreloc.exe .\Metal_Warrior_2.sid .\MW2.sidAfter this step, the SID file can be played seamlessly within C64AI without any compatibility issues.
Relocated SID file