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From: bob@grebyn.UUCP
Newsgroups: comp.os.minix
Subject: First Impressions of Minix
Message-ID: <288@grebyn.COM>
Date: Tue, 14-Apr-87 20:47:39 EST
Article-I.D.: grebyn.288
Posted: Tue Apr 14 20:47:39 1987
Date-Received: Thu, 16-Apr-87 00:31:05 EST
Organization: Grebyn Corporation; Vienna, VA
Lines: 48

Well, I've gotten the executable files and had a chance to play.  I
am, in a word, disappointed.
 
The basic problem is that the thing is too closely tied to the
hardware.  There's no good reason to bypass the BIOS for everything.
Specifically, MINIX goes straight to the screen.  This is fine, when
you do it right.  But MINIX doesn't, so MONO and EGA screens get
garbaged in odd ways.  The right way is to call the BIOS to set modes,
set cursor scan start and end, etc, and then and only then - when you
know exactly what adapter you're dealing with - write directly to the
screen memory after checking for vert or horiz scan.
 
Keyboard handling is also bad, due to arbitrary assumptions and a
too-low-level interface tied to assumed hardware.
 
After reading the book three times, I have formed the opinion that
Tanenbaum knows less about DOS than he will admit.  He is just plain
wrong about many things (like his statement that DOS does a physical
write of a disk block whenever you add even 1 char to it), and
academically snobby / vague about others.
 
Due to this low-level implementation, you can't use any of the
thousands of DOS device drivers (like for my Bernoulli box, my custom
clock chip, etc).  I'm not impressed by a so-called operating system
that has to be recompiled to move from my XT to my XT + Bernoulli
system.
 
What to do?  I have scoped the effort needed to convert MINIX to
something useful viv-a-vis the rest of the PC world.  This includes
supporting DOS device drivers first and foremost, and handling the
screen right so my EGA doesn't spend half it's life blanked out, and
supporting ASYNC ports, etc.  Add all of this up and you're talking an
awful lot of work.
 
Is it worth doing?  I don't think so.  What do I gain once I've fixed
it up?  A minimal UNIX, with more overhead than useful features.
 
Weigh the plusses against the minuses, and in my opinion it's not
worth spending any more hours on MINIX.  It's neat as a teaching tool
(if you take lots of the DOS stuff with a grain of salt), but I've got
real work to do. I'll stick with DOS.
 
  - Bob Baumann
-- 
Robert A. Baumann, CCP, CDP		{decuac, seismo}!grebyn!bob
Computerwise Consulting Services	bob@grebyn.com
P. O. Box 813				bob%grebyn.com@seismo.css.gov
McLean, VA  22101			(703)-280-2809