OS/2 PACK archive

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File Format
Name OS/2 PACK archive
Ontology
Extension(s) .??_, .??@, others

OS/2 PACK archive is a compressed archive format used for software installation on OS/2.

There are at least four versions of it, possibly more. For the version that starts with bytes a5 96 fd ff, see OS/2 PACK2 archive.

PACK format is generally associated with the OS/2 PACK.EXE and UNPACK.EXE utilities.

Contents

Format details

Compression scheme

The compression is a kind of LZW with 12-bit codes. Code 0 marks the end of data; codes 1-256 are literals; 257-4095 are dynamic. If the code table is full, the least-recently-used leaf code is reused.

This is the same compression used by LoadDskF/SaveDskF.

Other format details

The format supports OS/2 extended attributes, compressed independently following the compressed file data.

Identification

Files start with bytes a5 96, followed by 00 14, or ff ff, or fe ff.

See also OS/2 PACK2 archive#Identification.

Software

OS/2 software:

Other:

Sample files

Version "00 14":

Version "ff ff":

Version "fe ff":

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