04 Apr 2026
.LBR ("library") files are analogous to modern ZIP files in that they are used to containerize many, usually related, files into one file. .LBR files contain a compact directory of the contents. Specific tools are needed to remove, add, list or manage LBR/library contents.
Unlike .ZIP files .LBR files are not compressed. LBR predates .ZIP files by about a decade; here's two Wikipedia pages on the subject: .LBR and .ZIP.
File-compression with the intent of saving disk space does exist on CP/M using a method called "squeeze"; common names for squeeze and un-squeeze programs are SQ.COM, USQ.COM, and similar. SQ/USQ change the middle character of the filename extention to "Q" to indicate that the file is squeezed; therefore FILE.LBR squeezed with SQ.COM would be renamed to FILE.LQR. (SQ and USQ save and restore the missing middle letter.)
The relationship between libraries and squeezing is analogous to that between unix tar and compress or pack, which predate lbr/sq by a few years. There is essentially zero .ZIP support for CP/M, and little support for .LBR outside of CP/M.
In 2026 LBR files are quite useful; however I don't see a lot of value in squeezing for space.
I have replaces LU.COM with NULU.COM, which is MP/M compatible. NULU has
compatible command line syntax. NULU.COM on MP/M and CP/M both extracts and
builds .LBR files. The command line syntax is a bit wordy but it is a good
program and very consistent. The NULU.COM program is on the bootable A-drive
disk image, or downloadable. The basic syntax is:
NULU -O filename.LBR -E filename
Where -O filename.LBR specifies the .LBR file to extract from,
and -E filename is which file to extract, but can be -E
*.* to extract all files. Use -L (filename optional) to
list files in the library. For further usage read the help file.