SQ (program)
Encyclopedia
SQ was a program used in the early 1980s on both DOS
and CP/M
computer systems to compress files so they use less space. Files compressed by SQ are identified by changing the middle initial of the extension to "Q", so that text files ended with the extension .TQT, executable files ended with the extension .CQM or .EQE, documents with .DQC, etc.
Groups of files were often combined into an archive using the LU program, which created .LBR
files containing all the files needed for a particular group, such as all the files needed to install an application. Typically such files were either individually compressed (because LU did not compress files) or the LBR archive was itself compressed with SQ.
With the development of the ARC program (which combined both compression and archiving into one program) and its ARC
archive file format, SQ essentially became obsolete on most systems, except CP/M, which lacked an ARC port for several years. On CP/M systems, the CRUNCH compression program was written to implement the LZW algorithm (as ARC did) and plug the gap.
DOS
DOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related...
and CP/M
CP/M
CP/M was a mass-market operating system created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc...
computer systems to compress files so they use less space. Files compressed by SQ are identified by changing the middle initial of the extension to "Q", so that text files ended with the extension .TQT, executable files ended with the extension .CQM or .EQE, documents with .DQC, etc.
Groups of files were often combined into an archive using the LU program, which created .LBR
LBR (file format)
The .LBR file format was an archive file format used on CP/M and DOS operating systems during the early 1980s. .LBR files were created by the LU program; later programs like NULU arrived for .LBR creation, and many tools such as LT and QL were capable of extracting from .LBR archives...
files containing all the files needed for a particular group, such as all the files needed to install an application. Typically such files were either individually compressed (because LU did not compress files) or the LBR archive was itself compressed with SQ.
With the development of the ARC program (which combined both compression and archiving into one program) and its ARC
ARC (file format)
ARC is a lossless data compression and archival format by System Enhancement Associates . It was very popular during the early days of networked dial-up BBS. The file format and the program were both called ARC...
archive file format, SQ essentially became obsolete on most systems, except CP/M, which lacked an ARC port for several years. On CP/M systems, the CRUNCH compression program was written to implement the LZW algorithm (as ARC did) and plug the gap.