Scm is a portable R5RS Scheme implementation written in C. * Support for SICP, R2RS, R3RS, and R5RS scheme code. * Is fully documented in TeXinfo form, allowing documentation to be generated in info, TeX, html, nroff, and troff formats. * Supports inexact real and complex numbers, 30 bit immediate integers and large precision integers. * Many Common Lisp functions: logand, logor, logxor, lognot, ash, logcount, integer-length, bit-extract, defmacro, macroexpand, macroexpand1, gentemp, defvar, force-output, software-type, get-decoded-time, get-internal-run-time, get-internal-real-time, delete-file, rename-file, copy-tree, acons, and eval. * Char-code-limit, most-positive-fixnum, most-negative-fixnum, and internal-time-units-per-second constants. *Features* and *load-pathname* variables. * Arrays and bit-vectors. String ports and software emulation ports. I/O extensions providing ANSI C and POSIX.1 facilities. * Interfaces to standard libraries * Available add-on packages including an interactive debugger, database, X-window graphics, BGI graphics, Motif, and Open-Windows packages. * A compiler (HOBBIT) and dynamic linking of compiled modules. * User definable responses to interrupts and errors, Process-syncronization primitives. Setable levels of monitoring and timing information printed interactively (the verbose function).