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Amiga DiskMasher compressed archive magic bytes (.dms)

.dms file signature: 44 4D 53 21 | application/octet-stream

Amiga DiskMasher System (DMS) is a legacy compressed disk-image archive format originally created by Dave Miller for the Commodore Amiga platform. It was used to store and distribute Amiga floppy disks in a compressed form, especially for software backups, preservation, and bulletin board system sharing. The format is largely obsolete, and some archives may contain intentionally protected or malformed data that requires cautious handling in modern tools.

Safe

Magic Bytes

Offset 0
44 4D 53 21

Sources: Gary Kessler

Extension

.dms

MIME Type

application/octet-stream

Byte Offset

0

Risk Level

Safe

Validation Code

How to validate .dms files in Python

Python 
def is_dms(file_path: str) -> bool:
    """Check if file is a valid DMS by magic bytes."""
    signature = bytes([0x44, 0x4D, 0x53, 0x21])
    with open(file_path, "rb") as f:
        return f.read(4) == signature

How to validate .dms files in Node.js

Node.js 
function isDMS(buffer: Buffer): boolean {
  const signature = Buffer.from([0x44, 0x4D, 0x53, 0x21]);
  return buffer.subarray(0, 4).equals(signature);
}

How to validate .dms files in Go

Go 
func IsDMS(data []byte) bool {
    signature := []byte{0x44, 0x4D, 0x53, 0x21}
    if len(data) < 4 {
        return false
    }
    return bytes.Equal(data[:4], signature)
}

API Endpoint

GET /api/v1/dms
curl https://filesignature.org/api/v1/dms

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .dms file?

A .dms file is an Amiga DiskMasher compressed archive. Amiga DiskMasher System (DMS) is a legacy compressed disk-image archive format originally created by Dave Miller for the Commodore Amiga platform. It was used to store and distribute Amiga floppy disks in a compressed form, especially for software backups, preservation, and bulletin board system sharing. The format is largely obsolete, and some archives may contain intentionally protected or malformed data that requires cautious handling in modern tools.

What are the magic bytes for .dms files?

The magic bytes for Amiga DiskMasher compressed archive (.dms) files are 44 4D 53 21 at byte offset 0. These bytes identify the file format more reliably than the extension alone.

How do I validate a .dms file?

To validate a .dms file, read the first bytes of the file and compare them against the known magic bytes (44 4D 53 21) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .dms files?

The primary MIME type for .dms files is application/octet-stream.

Is it safe to open .dms files?

Amiga DiskMasher compressed archive (.dms) files are generally safe to open. They are classified as low risk because they primarily contain data rather than executable code. However, always ensure files come from a trusted source.