Why not Multics? (was Re: BSD tty security, part 3: How to Fix It)

[Chris Rende]

>From article <3096 at cirrusl.UUCP>, by dhesi%cirrusl at oliveb.ATC.olivetti.com (Rahul Dhesi):
> In <1991Apr30.142053.2313 at sctc.com> stachour at sctc.com (Paul Stachour) writes:
> 
> So why are we all using UNIX and its derivatives?  Why isn't Multics a
> commercial success even though it seems to have a unique place in
> history?
> 
> More specifically, where can we buy Multics to run on our favorite
> hardware?  Why can't we buy it?
> 
> Rahul Dhesi <dhesi at cirrus.COM>
> UUCP:  oliveb!cirrusl!dhesi

Problem number one is that Multics requires cetain support from the hardware
that it is running on. A normal Honeywell DPS8 could run GCOS, but not Multics.
Multics requires the addition of an "appending unit". This unit adds extra
security "stuff" to the CPU. Things like ring brackets, etc... Other computers
don't have these custom features that Multics requires.

Problem number two is that Multics was written for a 36 bit architecture.
Since Multics was invented in the 1960's, portability wasn't a big thing yet.
It would be a pain to port the 36 bit, 17 bit, and 72 bit stuff over to
today's 32 bit world.

Problem number three is Multics' size. Multics was designed to be everything
to everyone at the same time. That means that it has all-the-nice-OS-features-
that-you-would-ever-want-and-known-to-mankind builtin to the system. That
makes Multics quite huge in terms of RAM, disk, and CPU usage.

The creators of Unix chose the opposite path: small is beautiful. So, they
took out things like access control lists and gave us rwxrwxrwx instead.

With the advent of smaller computers it became possible to fit Unix on a
smaller computer. Smaller computers poped up all over the place. Since there
was no way to put Multics on the smaller computers, people used Unix instead.
(Or MSDOS, etc...).

The fun part is that even low end computers aren't so small any more.
And there is enough extra RAM, disk, and CPU time to add this or that
feature to Unix. Over the course of time we will probably add back into
Unix everthing (and more) that was carved out of Multics in the first place.

Unfortunately, it will likely be a hack job. This is where Multics had the
advantage: Multics was clean and consistent from top to bottom. For example,
the command line switch "-all" means <<all>> for all commands. And, for
all commands, "-a" is short for "-all".


car.
-- 
Christopher A. Rende           Central Cartage (Nixdorf/Pyramid/SysVR2/BSD4.3)
uunet!edsews!rphroy!trux!car   Multics,DTSS,Unix,Shortwave,Scanners,UnixPC/3B1
car at trux.mi.org                Minix 1.2,PC/XT,Mac+,TRS-80 Model I,1802 ELF
trux!ramecs!car     "I don't ever remember forgetting anything." - Chris Rende