BM$ File

What are BM$ files and how to open them

Are you having problems opening a BM$ 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 BM$ files.

What is a BM$ file?

A .BM$ file is a TSComp Compressed Data file.

TSComp Compressed Data files are archive data created by the TSComp program, a legacy compression tool used on older PCs for grouping one or more files into a compressed archive. These files preserve the original content of each archived file in a lossless format so that it can be restored exactly as before compression. The archive may contain a single file or multiple files, depending on how it was created. When multiple files are included, the archive contains internal records of each file's name (often in DOS 8.3 format), modification timestamp, and compressed size.

TSComp archives are generated by the TSComp utility. After creation, these archives are commonly extracted using compatible decompression tools such as deark, which understand TSComp's structure. This format was broadly used where archive extensions were altered by changing the final character to a dollar sign ($) or an exclamation mark (!), especially in single-file archives, to avoid name collisions. For multi-file archives, extensions like LIB or CMP are common.

Files start with an identifying header: the first eight bytes are 65 5D 13 8C 08 01 03 00 in hexadecimal. At offset 8 a single byte indicates the "filename style" value: 1 means the archive was created without wildcards (single file), 2 means with wildcards (multiple files). Subsequent bytes record data such as compressed size of the first archived member (little-endian 32-bit at offset 14), and the offset to the next file record if present (offset 18). There are also set-zero fields at offsets 18 and 26 which act as delimiters or reserved space.

How to open BM$ files

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

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: August 24, 2026

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about BM$ file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.