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C64 disks & images, explained
New to all this? Start here - what a D64 actually is, and how the C64 world uses it.
What is a D64 file?
A D64 is a digital copy of a Commodore 1541 floppy disk - a single file on your PC that holds everything the real 5.25-inch disk did: its directory and all its programs. It's always 174,848 bytes (about 170 KB), mirroring the 1541's 35 tracks. Think of it as the C64 world's equivalent of a disk in a box - an emulator or a piece of hardware treats it exactly like the physical floppy.
What's the difference between D64, D71, D81, D80, D82 and DNP?
They're images of different Commodore drives. D64 is the classic 1541 disk (170 KB). D71 is a double-sided 1571 (340 KB). D81 is the 3.5-inch 1581 (800 KB). D80 and D82 are the big PET/CBM 8050 and 8250 drives. DNP is a CMD “native partition” - a hard-disk-style container up to 16 MB, used by SD2IEC and CMD hardware. Retro Commander reads and writes all of them, and opens each one like a folder.
And G64, NIB, T64, TAP, PRG and CRT - what are those?
D64 stores a disk's decoded sectors; G64 and NIB instead keep the raw, low-level track data, which is what you need to preserve copy-protected disks faithfully. PRG is a single program, not a disk - one file with a two-byte load address. T64 is a container that only holds PRG files (a relic of an old emulator; despite the name it is not a real tape). TAP is a true Datassette tape recording. CRT is a cartridge image. Retro Commander edits the disk-image family - D64, D71, D81, D80, D82 and DNP - and opens G64 and T64 read-only, so you can browse them and copy files out.
How do I use a D64 with an emulator?
In an emulator such as VICE you “attach” the D64 to virtual drive 8, then on the C64 type LOAD"$",8 and press RETURN to list the directory, or LOAD"NAME",8 followed by RUN to start a program. Most emulators also offer a “smart attach / autostart” that does it in one step. Retro Commander prepares and edits the disks on your PC, and can hand a file to VICE or another emulator with F1; the emulator runs them.
How do I use disk images with real hardware?
The cheapest route is an SD2IEC - a small device that pretends to be a 1541, so you drop D64/D81 files onto an SD card and mount them. For full fidelity there's the 1541 Ultimate, Ultimate-II+ and Ultimate-64, plus the Pi1541, which emulate the 1541 cycle-exactly and can run G64s and copy-protected images. Retro Commander connects directly to the Ultimate family over your network - see what that gives you.
What are GCR, half-tracks and copy protection - and when do I care?
The 1541 wrote data as GCR, a magnetic encoding, and games often abused it with non-standard tracks, odd sync marks or “fat tracks” to stop copying. A plain D64 discards that low-level detail, so an original protected disk may not run from a D64 - for those you need a G64 (or a flux dump) that keeps the raw encoding. For everyday demos, tools and already-cracked games, D64 is perfectly fine.
Where do I find disk images legally?
Scene productions - demos, intros and music - are released for free by their authors on CSDb. Gamebase64 catalogues games, and the Internet Archive hosts large collections. New commercial titles come from homebrew publishers such as Protovision, RGCD and itch.io. Remember that many original games are still under copyright: stick to scene and homebrew releases, and anything explicitly shared by its makers.
How were these images made, and can I image my own disks?
Most images were “dumped” from real floppies. For ordinary disks, a 1541 with a transfer cable (X1541 or ZoomFloppy) plus software like OpenCBM does the job. For copy-protected or fragile disks, preservationists use flux-level hardware - KryoFlux, Greaseweazle, or a Pi1541/Ultimate - to capture the raw magnetics into G64 or flux files for archival.
Is a disk image a “ROM”? Will it run a game by itself?
No. A disk image is just storage - the equivalent of a floppy in a box. You still need a C64, real or emulated, to run what's on it, along with its built-in KERNAL and BASIC ROMs. Retro Commander manages the disks; the C64 - hardware or emulator - does the actual running.
Retro Commander specifics
What is Retro Commander 1.0 alpha?
The native rebuild of Retro Commander: a keyboard-first C64 disk image manager for Windows in the Norton and Star Commander tradition, now a few megabytes with no .NET runtime. It does everything the classic 0.9 did for everyday disk work, plus editing disks directly on your Ultimate, show deleted and restore, stamps, find-in-disks, favourite folders and single-screen mode. It's the version that gets every new feature from here on; the classic 0.9 stays available in the archive on the download page. The feature tour has the details, and the about page the story behind it.
Which devices are supported?
The Ultimate 64 and Ultimate-II+ from ultimate64.com, and the C64 Ultimate from commodore.net. They share the same REST + FTP interface. The app doesn't gate behaviour on a specific firmware version, but very old firmwares may be missing some endpoints; keep yours reasonably current. Without a device you can still launch into an emulator such as VICE.
Does it run on Mac or Linux?
No - Retro Commander is a Windows app, for Windows 10 and 11 (x64). There's no Mac or Linux build planned for 1.0.
Do I need .NET or anything else installed?
No. Version 1.0 is a native Windows app with no runtime to install. Take the installer (start menu, optional desktop shortcut and file associations) or the portable zip, which holds a single RetroCommander.exe.
Why does Windows warn me when I start it?
The alpha builds aren't code-signed yet, so Windows SmartScreen may show a warning the first time. Choose More info and then Run anyway. The SHA-256 checksum on the download page lets you check the file is the one we published.
Does the alpha expire?
Yes - each alpha build carries an end date, and a newer build is posted on the download page before it arrives. An expired build tells you so and closes; your disks and settings are untouched.
Do I need an account?
Yes, once. The first start asks for your email and a password, and you confirm your email from the link you receive. During the beta that switches on every feature. Your account - change email or password, sign out, manage devices - lives on the Account tab in Settings.
Where is the Diskbench, or the DirArt workbench?
Both were features of the classic 0.9 and are not part of 1.0. Single-screen mode takes over the Diskbench job of filling one disk from many, and Stamps take over directory art: save a block of directory rows, or draw one in the C64 font, and insert it into any disk.
Where are settings stored?
In a settings\ folder next to the executable when that folder is writable (so the portable build stays portable). Otherwise in %APPDATA%\RetroCommander\settings.json. On its first run, 1.0 copies over the settings of the classic 0.9 app if it finds them.
Can I connect to multiple Ultimate devices?
One at a time. A scan lists every device it finds; picking one replaces the host in Settings, and your connection details stay saved between sessions. See Connecting to your Ultimate.
Is there telemetry?
Only operational metrics and crash reports - never the contents or names of your files. The app reports session start and end with a periodic heartbeat, and counters such as how many disk images you open or edit and files you transfer, so we can gauge load and prioritise features. If the app crashes, it sends the error and a stack trace with personal paths cut out. There are no third-party analytics or advertising SDKs, no cross-site tracking cookies, and we never sell your data. Over the network the app talks only to your Ultimate device on the local network and our own server (sign-in, licence, update check, these counters and crash reports). See the Privacy Policy for the full list.
Is the source available?
No - Retro Commander is a closed-source project. The Windows builds on the Download page are the only distribution. Bug reports, feature ideas, and screenshots are still very welcome via the contact page.
How do I report a bug?
Until a public issue tracker is up, send a short reproduction (what you did, what you expected, what happened) via the contact page, and mention the version shown in the app. Screenshots welcome.