MIT Scheme, general information (long message)

[Bill Rozas <JINX%OZ.AI.MIT.EDU@XX.LCS.MIT.EDU>]

There are currently 2 implementations of MIT Scheme:

"Gator" Scheme runs on HP 9000 series 200 (and old model 9836 plus
variants) computers under the Pascal 3.1 operating system.  It is
quite dependent on this operating system and the tools provided with
it.  This is currently our main implementation.  Most of the code is
written in Scheme, but the interpreter and support procedures
(operating system interface) are written in assembly language
(Motorola 68000) and Pascal (HP dialect).  There is a very
idiosincratic compiler (Liar) in this version which with motherly care
or luck can give very good performance, but which will not perform so
well without pampering.  There is also a very good editor (Edwin)
written in Scheme.  It is very similar to GNU Emacs, but its interface
to Scheme is (for obvious reasons) better.

CScheme (pronounced like "see-scheme") runs on a variety of machines
which have C compilers.  In particular, it runs on Vaxen (both BSD4.2
Unix and VMS), various flavors of Unix (HP-UX, Sun BSD), and is quite
portable, but may require some work on "strange" machines and/or
operating systems.  This version (the interpreter and support
routines, which are written in C) was originally written to illustrate
how a Scheme system could be built, not as a "production" version.
Its main emphasis was clarity, rather than efficiency.  As of late,
with (slowly) increasing efficiency and use, it is becoming the base
for a variety of projects.  Its performance is adequate (although not
great) on the latest generation single user workstations (Suns, HP
9000 series 300, etc).  There is currently no compiler for this
version.  There is a moderately good (although not perfect) interface
to GNU Emacs, and a barely adequate interface to DEC Emacs for VMS.

Both systems are pretty similar as far as "normal" users are concerned
(the systems share the code written in Scheme although they are
currently somewhat out of phase).  Both versions also require large
amounts of memory (upwards of 4 Mb for Gator Scheme with all the
features, somewhat over 2 Mb for Cscheme).

Within the next few months (by September '86 probably) we will shift
 from Gator Scheme to CScheme (CScheme will become our main
implementation), and there will be a (new) compiler for CScheme with
back ends at least for the common machines (68k family and Vax).
Eventually we plan to have a C back end also (does anybody know of a
portable dynamic loader for C/Unix ?).  Edwin will also be ported to
CScheme (at least under versions of Unix providing the curses(3)
library).

For more information about either version, send (arpa) mail to

SCHEME-TEAM%MIT-OZ@MIT-MC

or US Snail to

Scheme Team
c/o Prof. Hal Abelson
545 Technology Sq. rm 410
Cambridge MA 02139

For particular information about CScheme, send mail to

INFO-CSCHEME%MIT-OZ@MIT-MC (send mail to info-cscheme-request to be
added to this mailing list)

To obtain a copy of MIT Scheme

1) If you want CScheme, and have access to the arpanet, a "tar" file
(for Unix) exists on MIT-PREP /scheme/dist.tar .  There is usually a
"compressed" (dist.tar.Z) file also.  If the file does not exist for
any reason, log in (via telnet) to MIT-PREP as scheme (no password).
The files will be re-generated by the log in program.

2) If you can use ftp over the arpanet, but cannot use a tar file, get
in touch with us describing what version you want, and we may be able
to arrange some way to get the sources across the net.

3) Otherwise, try to get a copy from someone who already has it. 

4) As a last resort (unadvisable), send $200 to the address above, and
specify what form of tape you want.  We can currently provide
	1600 bpi standard tar tape.
	1600 bpi standard VMS backup tape.
	HP-UX cartridge tar tape.