.KC File Extension

KeyKit Collection

Developer Tim Thompson and AT&T
4.0  |  3 Votes

What is a KC file?

A KC file is a KeyKit Collection used by Tim Thompson's KeyKit. It contains a set of named musical sequences you can play in KeyKit. KC files are most often used to group similar percussion sequences into collections that can be opened and played using KeyKit's Blocks tool.

More Information

Screenshot of a .kc file in KeyKit
KC file open in KeyKit

KeyKit is an open source programming language and graphical interface used to create MIDI music. Developer Tim Thompson created the language and accompanying program in the 1990s, during the time he worked at AT&T. While KeyKit was originally released through AT&T, it is now available for free from GitHub.

KeyKit was developed for use on Windows NT, but still works on modern Windows, Linux, and Raspberry Pi systems. So if you have a KC file sitting on your computer, you can still open it and play the musical sequences it contains using KeyKit. Additionally, KeyKit comes loaded with a number of sample KC files, including rock-, jazz-, rap-, funk-, and reggae-inspired collections.

How to open a KC file

To open a KC file in KeyKit:

  1. If you haven't already, download and install KeyKit using the source code available on GitHub (linked below).
  2. Open KeyKit and click within the blank section of the program's GUI. From the menu that appears, select Tools1 → Blocks.
  3. Click anywhere within the GUI's blank section to open the Blocks tool.
  4. Within the Blocks tool, select More → Read Collection. Then, navigate to the location of your KC file, select it, and select Open.

The musical sequences contained within your KC file should now be available to play within KeyKit. To confirm this, select one of the One beat buttons that appears within the Blocks tool. A list of the sequences contained within your KC file should appear beneath the button.

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Programs that open KC files


macOS Kernel Extension Boot File

Developer Apple
3.0  |  2 Votes

A KC file may also be a system file used by macOS. It contains data macOS uses to load kernel extensions, or kexts. While kernel extensions are deprecated, macOS still uses some KC files, which can be found in the Macintosh HD/​System/​Volumes/​Macintosh HD/​boot directory.

More Information

A kernel is the foundational layer of an operating system. It communicates with a PC's hardware and manages resources, such as RAM and CPU.

A macOS kernel extension is a bundle that extends the functionality of a user's kernel, allowing it to perform additional low-level system tasks. Kexts run in kernel space, which gives them the ability to perform tasks that user-space applications and processes cannot.

The primary KC file macOS uses to boot kernel extensions is BootKernelExtensions.kc. You may encounter additional KC files, which contain a string of additional numbers and letters after the .kc extension.

How to open a KC file

KC files are not meant to be opened.

Programs that open KC files

Not meant to be opened

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