Squeeze

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Revision as of 02:09, 6 December 2012 (view source) JTN (Talk | contribs) (lk Wikipedia page) ← Older edit		Revision as of 11:05, 27 January 2013 (view source) JTN (Talk | contribs) (+ lbrate) Newer edit →
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	* [[CFX]] (DOS/Unix)		* [[CFX]] (DOS/Unix)
		+	* [http://www.svgalib.org/rus/lbrate.html lbrate] (Unix)
	* On CP/M (or emulators):		* On CP/M (or emulators):
	** The original tools were SQ/USQ. See for instance the [http://www.classiccmp.org/cpmarchives/cpm/mirrors/oak.oakland.edu/pub/cpm/squsq/ SQUSQ] directory of the Oakland CP/M archive.		** The original tools were SQ/USQ. See for instance the [http://www.classiccmp.org/cpmarchives/cpm/mirrors/oak.oakland.edu/pub/cpm/squsq/ SQUSQ] directory of the Oakland CP/M archive.

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Revision as of 11:05, 27 January 2013

File Format
Name	Squeeze
Ontology	Electronic File Formats Compression Squeeze
Extension(s)	.?q?, .qqq

Squeeze was a method of compressing single files popular on CP/M, devised by Richard (Dick) Greenlaw(?) circa 1981. It was superseded by Crunch and later CrLZH. Squeezed files were common in LBR archives. It uses Huffman compression.

Squeezed files were signified in CP/M's 8.3 filename format by replacing the middle letter of the extension with Q (.?Q? -- so FOO.TXT became FOO.TQT), with the extension .QQQ used for corner cases such as a blank extension.

The /usr/share/misc/magic file on Linux systems suggests that it was perhaps also in use on the Apple ][ platform.

Tools

• CFX (DOS/Unix)
• lbrate (Unix)
• On CP/M (or emulators):
  • The original tools were SQ/USQ. See for instance the SQUSQ directory of the Oakland CP/M archive.
  • The later LT31 deals with extracting from all of Squeeze, Crunch, CrLZH and LBR formats. Widely available in CP/M archives, e.g. LT31.LBR

References

• See the SQUSQ directory on CP/M archives for various source code and documentation (much of it, unfortunately, itself squeezed/crunched).
• The file header follows a similar/compatible structure to Crunch and CrLZH.
• FIXME: is the exact compression algorithm documented anywhere?
• Wikipedia:SQ (program)