What is a .ZIP?
A .ZIP file is an "archive" file that contains one or
more larger files in a special compressed format. (Think of it as
putting several large feather pillows into a single bag,
then squishing out all of the air: you have one container
with several items in it that takes up much less space
and is easier to handle than
the individual items stored alone).
Compressed files are used for electronic file transfers
because they significantly cut your
downloading time (in half or even less) and you only have to
download one file instead of the many files it often takes to
run a program. File compression also makes it
possible to fit large collections of files onto one
File compression works on a combination of a few basic principles such
as tokenizing, elimination of repetition, and pattern identification
combined with some very clever mathematics. There are two basic types
of compression: "lossless" and "lossy". Lossless compression is used on
program and datafiles. This ensures that the files you get out of the
archive are identical to the originals. Lossy compression can give much
higher compression ratios, but you cannot guarantee that the decompressed
file will match the original. For programs and data, this could be
disastrous. Thus, lossy compression is used for image
and audio files, where a few missed bits will not be important. For
example, JPEG files use a lossy compression.
Where do I get an UnZip program?
There are many file compression programs available, with
various options for compression degree, speed of execution,
etc. The original, and still one of the most popular for MS-DOS (and Windows) computers
is PKZip and its companion de-compression program PKUnZip, both
developed by PKWare. Another popular
archive utility for Windows is WinZip.
Other compression/ decompression utilities are listed below.
In order to
decompress a .ZIP file like we use on our site,
you need a copy of the current
version of PKUNZIP, which is a shareware program included with
the PKZip package. If you do not have a copy,
click here to find a download site for it.
If you need help on downloading, see our Downloading basics page.
The PKZip package is a self extracting archive, so
before you use it the first time, you must
The program will then extract all of the constituent files from
the archive, one of which will be PKUNZIP.EXE. Remember that PKZip
is a shareware package, and requires registration with the author after
a specified trial period.
- First, create a subdirectory on your
hard drive, such as C:\ZIP, then copy the PKZip program archive
you just downloaded (such as PKZ204G.EXE) to that
- In DOS:
- change to the C:\ZIP directory; then
- execute the file like a program by typing in its name,
- In WINDOWS 3.x File Manager, or Win'95 Explorer:
- move the PKZip program archive to the C:\ZIP directory if it
is not there already; then
- double-click on that program
to decompress it.
How do I use PKUnZip?
- First, create a directory on your hard drive for the file you want to unZIP. (such as C:\MAXI)
- Next, copy the .ZIP file to that directory.
- Change to the directory.
- Run the PKUNZIP program.
Since PKUNZIP is a DOS application/utility, it is best to run it from a C:>
DOS prompt. The basic command is PKUNZIP file.zip. For example,
if you were unZIPing our MAXI Disk program (MDISK42.ZIP), the command
That's all there is to it!
How do I use WinZip?
WinZip (as well as most of the other newer Windows based ZIP utilities), use
a "Drag and Drop" interface. You can open a ZIP file by either:
- Using Windows 3.x FileManager or Win'95/NT WindowsExplorer to associate
the ZIP file extension with the WinZip application; then
- Double click on the selected ZIP file from Windows 3.x FileManager or Win'95/NT WindowsExplorer;
- Use Windows 3.x FileManager or Win'95/NT WindowsExplorer to drag
the ZIP file over to the WinZip icon.
Other ZIP utilities and archive managers