C10 File

What are C10 files and how to open them

Are you having problems opening a C10 file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your C10 files.

What is a C10 file?

A .C10 file is a Virtual MC-10/Alice Tape Image file.

Virtual MC-10/Alice Tape Image files are digital replicas of cassette tapes used by the Radio Shack TRS-80 MC-10 and its French clone, the Matra Alice. They serve to store programs and data in the same format that real cassette tapes used in those machines, so that emulators or compatible systems can load them just like a physical tape would.

These images are typically generated by programs that emulate the MC-10 or Alice computers, or by tools that convert actual cassette recordings into a compact digital form. Emulators like XRoar accept these images (usually with the extension .c10) as input when simulating the MC-10's cassette tape interface. After being loaded, the contents can be accessed via the MC-10's BASIC commands (for example CLOAD or CLOADM); programs saved from the original system can also be converted into tape image files for preservation or sharing.

Internally, the cassette format begins with a leader made up of 128 bytes of 0x55, followed by a "Namefile" block, a pause, another identical leader, one or more "Data" blocks, and finally an "End of File" block. Each such block starts with a sync of 0x3C, includes a block type byte (00h = Namefile, 01h = Data, FFh = End of File), a block-length, the data-payload, a checksum (sum of block type, length, and payload), and is enclosed by 0x55 bytes at start and end. Data is encoded using frequency shift keying: a logic-0 is represented by a 1200 Hz sine wave cycle and a logic-1 by a 2400 Hz cycle, giving approximately 1500 baud.

How to open C10 files

Important: Different programs may use files with the C10 file extension for different purposes, so unless you are sure which format your C10 file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested seven different C10 openers which you will find listed below.

Last updated: August 25, 2026

Various apps that use files with this extension

These apps are known to open certain types of C10 files. Remember, different programs may use C10 files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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