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C64 OS Printed User's Manual, System SD Card v1.04, Stickers and Business Card.

C64 OS v1.04 is now available for purchase. The printed User's Guide has been updated, with 4 more pages, improved typography and layout, and updated information about new and improved features.

The Starter Bundle is now 2X the capacity, and the Standard Bundle now includes a pre-built IDE64 disk image for use in VICE. All the new libraries, drivers, tools and Utilities are included. Many bugs have been fixed. The set up, installation and first-run configuration experience has been improved.

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Already purchased C64 OS?
Update to v1.05 for free.

If you purchased a copy of C64 OS (v1.x), you can download system updates for free.
They are installed in a few simple steps with the built-in Installer.

Installing Software Updates is easy as 1, 2, 3.

Eliza for C64 OS - Released Christmas Eve 2023

A whole new imagining of the classic 1960's "Eliza" chat bot is now available as a C64 OS Application.

Eliza with About This App Utility. Eliza sample chat with original personality.

Compared to the BASIC version for the Commodore 64, Eliza for C64 OS absolutely flies. Responses come back instantaneously, as the whole engine has been rewritten from scratch in 100% 6502 assembly language.

As a C64 OS Application, Eliza gets all the bells and whistles, including:

  • MText formatted conversations
  • 4KB Scroll-back chat buffer
  • Customizable color theme
  • Save and load your conversations
  • Preview saved conversations from File Manager

Plus the ability to run Utilities at the same time, including using SID Preview to listen to your choice of SID music while you chat with Eliza.

Eliza sample chat with neurotic personality. Eliza in Pirate personality with Colors Utility.

Eliza for C64 OS comes with 5 personalities: Original, Pirate, Abusive, Neurotic and Robot. Each personality has a custom header logo. Plus, each personality has a unique greeting and a unique way to be insulted and stop talking to you. There are some fun easter eggs to find hidden in the personalities.

Available for purchase on itch.io for just $1.

We hope you have fun playing around with this venerable chat bot. And don't forget, in addition to saving the text of your conversations you can also take screenshots of memorable moments to share friends.

Find out more here: C64 OS Software Releases


What's new in v1.05

C64 OS version 1.05 brings a major architectural upgrade — Fast App Switching.3

You can configure C64 OS to use from 2 to 30 banks of an REU (if available) for use as fast app switching banks, allowing you to have up to 30 Applications open at the same time. Switch to Apps the same way you always have, but if they're already open, suddenly you switch to the open App instantly.

The Switcher

The new Switcher Utility can be used to see all your currently open Applications. Select an Application to either switch to it or quit or kill it.

Applications can be in different states, either: Running, Frozen or Unsaved. Switcher shows the Apps in the order they were most recently accessed. The Usage section tells you how many 64KB banks an Application is currently using.

You can now drop to the READY prompt from within any Application.

Switcher has been added by default to the bottom of the Utilities menu. Plus it gets the keyboard shortcut of CONTROL+S.

This allows you to quickly open Switcher from within any Application, which lets you switch directly from any current Application to any other open Application.

Switcher available in the Utilities menu. Switcher open above File Manager.

Fast Reboot

You can now drop to the READY prompt from within any Application. Simply pop open the Switcher and click "Drop to: READY." button. Just like when quitting to BASIC from File Manager you can hold the CONTROL key to remain in the partition and directory of the Application's open file.

From the READY. prompt, you do almost anything,4 including running BASIC or other C64 Software. You can also perform standard file management tasks using BASIC or JiffyDOS commands. When you're ready to return to C64 OS, load and run the C64 OS booter like normal. However, you'll boot abnormally fast, and be returned directly to the Application where you left off.5

The Usage Utility

The Settings Utility now offers to open the new Usage Utility. It's a major update to the older Memory Utility.

Run through the Configure Tool to change which Utility you want to open when you double-click the available memory indicator in the Status bar.

The default option is now Usage, but Memory or Peek are still available.

See every page of main memory, and how it's been allocated by the Application or the system. RAM usage is updated on a periodic timer, choose fast or slow updates to change how quickly the display refreshes.

Click individual pages to select them, and click Peek to open that page to peek into its contents.

This brand new display visualizes the usage of 64KB REU banks, from 128KB to 16MB. It also tells you how much of your REU has been used and how much is still available.

Click on any data bank to see which App bank allocated it. Or vice versa, click any App bank and you'll see what data banks it has allocated. Refreshes are automatic, with two speed settings, or click the Reload button to refresh immediately.

All the way back in C64 OS v1.0, the KERNAL keeps a running tab of the last 10 seconds of CPU usage. It's the same system that triggers the CPU busy indicator in the menu bar.

But for the first time, you can now visualize this CPU usage information with an animated and colorful bar graph.

Updated About This App

About This App was one of the first Utilities to be written. It's been rewritten and given a nice facelift by being entirely implemented with a Toolkit UI.

Application bundles collect settings and configuration of the App itself as well as Utilities that you run with that App. Click the Reset button to clear out this temporary data and restore an App bundle to its virgin state.

New Keyboard Shortcuts

To help out with Fast App Switching, several new keyboard shortcuts have been added. Hold COMMODORE+CONTROL+SHIFT while booting to prevent fast reboot and force a fresh clean boot with all Applications expunged from the REU.

Hold LEFT-SHIFT while switching to an Application that is already open to force its REU bank to be expunged and for it to be cleanly reloaded from storage.

Press CONTROL+R in the Save and Open Utilities to refresh the directory listing. This is useful because you can no fast switch back to File Manager, make changes there, and then fast switch back to the App with the Save or Open Utility already running.

Read the complete release notes for v1.05 on the Official Software Updates page.


What's new in v1.04

C64 OS Software updates add great new features: Support for Mouse Wheel; Mount .D64, .D71, .D81 and .DNP Images in File Manager1; Listen to SID Music; View new Commodore Grafix (CGFX) files including 3D-models, panoramic scenes, and short animation sequences2; Customize boot options in different modes; Access the native file system through VICE in File Manager; and much more.

CGFX: Animations and 3D Models

3D model of a Teapot in Commodore Grafix format.

Put your REU to new use. Explore a new class of media with interactive 3D models, in the new Commodore Grafix file format, and C64 OS Image Viewer.

Watch the video preview.

Animation sequence of Enterprise going to warp in Commodore Grafix format.

The new Commodore Grafix format supports 3D models, panoramas, and animation sequences with variable framerate up to 256 frames. Animations support looping, bouncing and loop count.

Watch the video preview.

SID Preview Utility

C64 OS now includes the SID Preview Utility. You can open SIDs in PSID format with a double-click from File Manager.

The SID Search Service lets you find and download from over 34,000 SIDs from HVSC that have been relocated for guaranteed compatibility with C64 OS. It's a first on the C64 that lets you listen to HVSC SID music from inside other Applications.

Search SID Service

Support for All Native Video Modes

The C64 OS gfx.lib now supports character-mode graphics. Image viewer can display PETSCII graphics, like this collection of hundreds of cute PETSCII BOTS.

Screenshots now capture the custom character set, and can be viewed in their original fidelity from inside C64 OS.

Save any HiRes or MultiColor bitmap frame from a CGFX animation or 3D Model or any other image file format as a custom boot screen graphic.

Interactive spinning Earth animation in Commodore Grafix format.

Some image matrices make the perfect candidates for both a looping animation sequence, and an interactive model. Pause the playback and you can freely rotate the object in either direction.

Watch the video preview.

3D model of a classic Porche in Commodore Grafix format.

You can create your own Commodore Grafix panoramas, animations and 3D models using a series of frames and the CGFX Creator Tool to bundle them into a RIFF/CGFX container.

Watch the video preview.

New Utilities, New Capabilities

Below are some new and updated Utilities. Enjoy SID tunes from within any other Application using SID Preview. Customize how the scroll wheel works with new Mouse settings. Mount disk images to copy files into and out of them with File Manager. Validate the integrity of downloaded files with Checksum.

New Utilities are available in free software updates.

These are just some of the new features in v1.04, which join the brilliant capabilities that C64 OS already offers you. Along with many bug fixes, stability improvements, improved support for IDE64, support for VICE FS, new features for TurboChameleon64, and usability improvements in existing Apps and Utilities across the board.

Read the complete release notes for v1.04 on the Official Software Updates page.


Install software updates for free

Amazing new features are becoming available for C64 OS all the time, and the ability to install them was designed to be a snap right from the very beginning. You can find the system updates on the Official Software Updates page.

Updates come in CARs. Why? Because CARs are great for transporting things. Pick the update that's right for your current version and copy it over to any device that C64 OS has access to. Double-click the CAR file in File Manager and the Installer Utility does the rest.

  1. Fast App Switching requires a 17xx-compatible REU. Compatible with Ultimate64, Turbo Chameleon 64, 1541 Ultimate II+, RAD, VICE, etc.
  2. After dropping to the READY. prompt, do not run C64 software that uses the REU. Any regular C64 software that modifies the contents of the REU will disrupt C64 OS, its Applications and their data.
  3. Fast Reboot requires a 17xx-compatible REU. Compatible with Ultimate64, Turbo Chameleon 64, 1541 Ultimate II+, RAD, VICE, etc.
  4. SD2IEC device is required to mount disk images.
  5. To view multi-frame images and animations requires a 17xx-compatible REU is required. Compatible with Ultimate64, TurboChameleon64, 1541 Ultimate II+, RAD, VICE, etc.


Last modified: Dec 25, 2023