Why are there two versions of REDUCE?
REDUCE runs on Standard Lisp and there are two versions of Standard Lisp that were developed primarily to support REDUCE, namely PSL and CSL (in that order chronologically). We only release distributions of REDUCE based on these two Lisps, although REDUCE can be implemented on other versions of Standard Lisp (and there is some experimental code to do this in the repository).
What user interfaces does REDUCE provide?
PSL REDUCE itself provides only a command-line interface (CLI). CSL REDUCE provides a graphical user interface (GUI) by default, but it provides a command-line interface if started with the --nogui option. GNU Emacs provides a GUI for PSL and CSL REDUCE via the REDUCE IDE package and GNU TeXmacs provides a GUI for PSL and CSL REDUCE via a plugin for running REDUCE. There is code in the repository for two other packages, redfront and XR, that provide GUIs for PSL, but neither is currently distributed as a pre-built binary and XR is somewhat out of date.
What start-up options does REDUCE provide?
For CSL REDUCE, running redcsl --nogui --help at a command prompt (assuming redcsl is on your search path – see Obtaining REDUCE) lists the start-up options.

Support for obtaining and installing REDUCE and for running REDUCE is available from this web site. Here are some other useful support links.

Project home page
the home page for the REDUCE distributions
Download a pre-packaged distribution
There are distributions for different platforms. Click on a release name in the File/Folder Name column to display the archive files available. Click on your chosen file to download it.
Browse the code repository
We use Subversion (SVN). For instructions and other options, go to the Project page and click on the Code button.
Join the mailing list
currently the main source of support for REDUCE
Bug tracker
If you think you have found a bug in REDUCE or any of its support or related systems then please report it here.
Discussion fora
a list of the current discussion fora
Redlog home page
REDLOG provides an extension of REDUCE to a computer logic system. It is included in the SourceForge distribution.
REDUCE support hosted on the REDLOG web site