John Brewer <jbrewer@spyglass.com> wrote:
+---------------
| 1970s C -- UNIX (ability to port an OS to new hardware just as number of
| platforms started exploding).
+---------------
You're off by a decade, and have causality backwards. Until circa 1980
the *only* platforms Unix ran on (in any quantity) were DEC PDP-11s and
VAX-11/780. The number of platforms started exploding in 1981 *because* --
almost *ENTIRELY* because -- of the introduction of the AT&T Unix "Binary
Sub-License, Limited Number of Users", which for the first time made
(re)selling Unix affordable on small platforms.
At the same time, Unix was the *only* operating system for which you could
"buy" (license) the source outright *and* which was written in a fairly
portable language (the PCC compiler was the key to portability, not C syntax),
thus meaning that tons of small start-ups [such as one I worked for] could
save about a megabuck by "buying" Unix instead of writing an O/S.
A secondary driving force that caused the "explosion" to occur at first
on Mc68000-based platforms was the availability "for free" (well, you had
to show you'd already paid AT&T for a license) of a mostly-working 68k port
from Steve Ward's group at MIT, including a PCC for the 68k that cross-
compiled from a PDP-11 or VAX.
So... $25000 to AT&T for a V.32 license, a magtape and a plane ticket
[and a copy of your AT&T license] to visit MIT, another magtape [& copy
of your AT&T lic.] to get BSD 4.1a (or so), and you had (almost) everything
you needed to be a "Unix systems vendor" on a J-random 68K platform.
*That's* why the number of platforms exploded: A change in Unix licensing,
a portable compiler, and a handy reference port. Without them -- and especially
without the licensing change, the "explosion" wouldn't have happened... then.
[It would have happened sooner or later, certainly, when some other O/S was
available in source form with a portable compiler and reasonable licensing...]
-Rob
-----
Rob Warnock, 7U-550 rpw3@sgi.com
Silicon Graphics, Inc. http://reality.sgi.com/rpw3/
2011 N. Shoreline Blvd. Phone: 415-933-1673 FAX: 415-933-0979
Mountain View, CA 94043 PP-ASEL-IA