Quantum compression

Quantum compression

The Quantum compression format is a somewhat obscure data compression method invented by a company called "Cinematronics" (written by an author identified as "David Stafford"). Rights to it were purchased at some point by Microsoft, and "Quantum" is one of the possible compression methods in a CAB archive.

Quantum (.Q) archiver

For DOS, PAQ.EXE is the compressor and UNPAQ.EXE is the decompressor. QWIN.EXE is the Windows decompressor (no Windows compressor exists). It is much faster and has more features (e.g., selective decompression) than the DOS decompressor. Each of these require at least a 386 CPU to run.

The latest known version is "0.97" (as of 15 May, 1995).

.Q archive header

This is immediately followed by the list of files:

(*) Strings are prefixed with their length. This takes one or twobytes. If the length is less than 128 then it is stored directly in onebyte. If it is greater than 127 then the high bit of the first byte isset to 1 and the remaining fifteen bits contain the actual length inbig-endian format.

Immediately following the list of files is the compressed data.

External links

*http://www.speakeasy.org/~russotto/quantumcomp.html
*ftp://ftp.sac.sk/pub/sac/pack/quant097.zip


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