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MacCBM

From Mac to 1541.

MacCBM is a native macOS GUI for OpenCBM and ZoomFloppy. Copy files between your Mac and a real Commodore 1541, save or write .d64 images, and build disks on the computer without touching the drive.

Download MacCBM Support MacCBM

Version 1.2 beta 3 · macOS 14+ · Apple silicon and Intel · Free

Actively developed. MacCBM will continue to evolve, with support for more drives, disk formats and useful features possible in future versions.

Screenshots

MacCBM in use

MacCBM in its Classic C64 appearance while copying a disk image to floppy
Classic C64 appearance — copying to floppy
MacCBM in its Modern C64 appearance while copying a disk image to floppy
Modern C64 appearance — copying to floppy
MacCBM in its macOS dark appearance while copying a disk image to floppy
macOS dark appearance — copying to floppy
MacCBM in its macOS light appearance while copying a disk image to floppy
macOS light appearance — copying to floppy
MacCBM with its built-in user guide open over the main window
Built-in help
MacCBM showing the dialog for creating a new disk image
Create a new disk image
MacCBM appearance settings with Classic C64, Modern C64 and macOS options
Appearance settings
Features

What MacCBM does

MacCBM is free to download and free to use. A contribution to support further development is welcome.

Using the drive

Transfer

  • Dual pane: computer on the left, live floppy on the right
  • Copy with the arrows or drag and drop, both ways
  • Drag files straight from Finder into the app
  • Drop a .d64 or .t64 onto the drive: copy programs, or write the whole image
  • Free-space check so a full disk is refused instead of failing silently
  • PETSCII-safe names so the C64 directory shows A–Z, not graphics

Real 1541

  • Detect ZoomFloppy / XUM1541 and drives 8–11
  • Read directory, save as .d64, write a .d64 to floppy
  • Format (NAME,ID), optional 40-track
  • Init = DOS I0 after swapping a disk — not a format
  • Bus reset when the IEC bus is stuck
  • Rename and scratch files, always with confirmation

On the Mac

Disk images

  • Open a .d64 or .t64 as a folder
  • Create an empty 35-track .d64
  • Add .prg, .seq, .usr, .p00, or .t64 into a D64
  • Extract files from D64 / T64
  • Convert T64 → D64
  • Delete files from a D64 (permanent; blocks are freed)

Computer pane

  • Finder-style browse, filters for .prg / .d64 / .t64
  • Multi-select: click, ⌘-click, ⇧-click, ⌘A
  • New folder, rename, move to Trash
  • Columns: name, type, size, 1541 blocks
  • Footer: files, selection, KB, blocks

The app

Mac app

  • Three appearances: Classic C64, Modern C64, macOS
  • Built-in help
  • Notification when a long save, write, or format finishes
  • Report a bug or suggest a feature from Help
  • Apple silicon and Intel, macOS 14+

Needs

  • ZoomFloppy (XUM1541)
  • Commodore IEC drive (1541 / 1541-II)
  • OpenCBM via Homebrew: brew install opencbm

MacCBM uses the command-line tools from OpenCBM by Spiro Trikaliotis. The app does not bundle or modify OpenCBM.

FAQ

OpenCBM on a Mac

Short answers if you want an OpenCBM GUI on macOS, with ZoomFloppy and a real 1541.

What is MacCBM?

MacCBM is a native macOS GUI for OpenCBM. It copies files and D64 disk images between a Mac and a real Commodore 1541 or 1541-II, using a ZoomFloppy or XUM1541 adapter.

Is there an OpenCBM GUI for macOS?

Yes. MacCBM is a free OpenCBM GUI built for Mac. It is a native macOS app, not a Windows program and not a command-line wrapper in a Terminal window.

What does MacCBM need?

macOS 14 or later, Apple silicon or Intel, a ZoomFloppy or XUM1541, and a 1541 or 1541-II. Install OpenCBM first:

brew install opencbm

How does it relate to OpenCBM?

MacCBM does not replace OpenCBM. It uses OpenCBM’s command-line tools and adds a dual-pane Mac interface for transfers, directories, format and disk images.

Is MacCBM free?

Yes. MacCBM is free to download and free to use. A voluntary contribution is welcome if you want to support further development.

Install

How to install

When you are ready to set it up, open the guide below. Install OpenCBM first, then MacCBM.

Show the install steps

1. Open Terminal

  • Press ⌘Space to open Spotlight.
  • Type Terminal and press Return.

A window with a % or $ is Terminal. Leave it open. Finder path: Applications → Utilities → Terminal.

2. See if Homebrew is already there

Homebrew is a free installer for Mac command-line tools.

brew --version

If Terminal prints a version (for example Homebrew 4.x), skip to step 4. If it says command not found: brew, install Homebrew first.

3. Install Homebrew (only if needed)

Paste this one line and press Return:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
  • Allow Terminal if macOS asks for network or developer-tool permission.
  • If a window says the command line developer tools are required, click Install and wait. Run the Homebrew line again if Terminal is still waiting.
  • Type your Mac login password and press Return. Nothing is shown as you type. That is normal.
  • Press Return to confirm prompts. This can take a few minutes.

When Homebrew finishes, it may print Next steps. If it does, run those two lines — they already match that Mac.

Apple silicon (About This Mac → Chip: Apple M1, M2, M3, or M4). Homebrew is in /opt/homebrew, which is not on PATH until you add it:

echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> ~/.zprofile
eval "$(/opt/homebrew/bin/brew shellenv)"

Intel (About This Mac shows a Processor such as Core i5 / i7). Homebrew is in /usr/local. That folder is often already on PATH, so Intel Macs frequently never see Next steps and brew works immediately. If it does not:

echo 'eval "$(/usr/local/bin/brew shellenv)"' >> ~/.zprofile
eval "$(/usr/local/bin/brew shellenv)"

Paste the two lines for your Mac, one at a time, Return after each. Then check again:

brew --version

Official installer: brew.sh

4. Install OpenCBM

brew install opencbm

Wait until it finishes. The last lines should not show an error.

5. Check that the tools are there

cbmctrl --help

You should see help text, not command not found.

6. Install MacCBM

  • Download MacCBM with the button at the top of this page.
  • Open the downloaded file.
  • Drag MacCBM to your Applications folder.
  • If macOS blocks the first launch, open System Settings → Privacy & Security and allow MacCBM.

macOS 14 or later, Apple silicon or Intel.

7. Open MacCBM and Detect

  • Plug the ZoomFloppy into USB.
  • Power the 1541 and connect the IEC cable.
  • Open MacCBM.
  • Click Detect (⌘D).

The right-hand column should show ZoomFloppy detected and a drive on 8–11.

If a command is not found

  • brew: command not found — run the two PATH lines in step 3 for your Mac (Apple silicon = /opt/homebrew, Intel = /usr/local), or quit Terminal completely and open it again, then retry brew --version.
  • cbmctrl: command not found — run brew install opencbm again and read the last lines.
  • ZoomFloppy not found in MacCBM — try another USB port, unplug and replug, power the drive, then Detect again.

You only install Homebrew and OpenCBM once. Later you can update OpenCBM with:

brew upgrade opencbm

OpenCBM on Homebrew · OpenCBM project

MacCBM is free.

If you enjoy using MacCBM and would like to support its continued development, you can leave a voluntary tip.

Support MacCBM