Barry Boone's utility ARCHIVER is the common tool to package files on the TI-99 and Geneve systems. Tim Tesch modified it for use with hard disks, in particular by changing the way the source directory is specified (you can provide a complete pathname).
Uncompressed archives contain the contents and metadata of a set of files in a single archive file. Uncompressed archives are stored in Int/Fix 128 format.
The archive file may be compressed to save space on the storage medium. The compression used in ARCHIVER is Lempel-Ziv-Welch, also known as LZW. The implementation uses a variable bit count, starting with 9 bits, then increasing up to 12 bits. When all entries are used up, it restarts with 9 bits.