THE UNIX /bin: Unix Workstations Connect
 
If Unix is multiuser, why would you want a Unix LAN?
 
Microbytes Daily News Service
Copyright (c) 1989, McGraw-Hill, Inc.
As new and faster processors reach the computer industry, more
powerful computers become accessible to end users. This is a
familiar refrain in magazine articles about personal computers.
It's even more applicable to Unix workstations, where new
technology is dramatically dropping prices to personal computer
levels. You might be thinking about adding an Ethernet port to
your microcomputer...or even running out and buying a
workstation! Now is the time to talk about networks and worksta-
tions.
 
 
What's a Workstation?
Almost anything with more CPU power than a toaster is being
called a workstation these days. But my idea of a workstation is
a computer with a high-resolution graphics display running a
multitasking operating system and window management software,
specifically designed to operate on a network. Any workstation
worthy of the name would also have an Ethernet port and a mouse.
 
This definition rules out a PC with an Ethernet card -- it's just
a PC with the ability to use a network. The Macintosh comes a
little bit closer, but it's really been designed to be a
stand-alone machine. A high-resolution terminal designed around
an Ethernet connection doesn't qualify -- it's not a computer.
Some Macs and PCs have been specially configured to use a
network. If they have high-resolution screens and multitasking
window managers, then they could actually be workstations by my
definition.
 
The key to having workstations is similar to that of eating
potato chips: Nobody has just one. A single diskless workstation
is useless without a file server (basically just a computer with
a lot of disk space). File servers are too expensive to dedicate
to a single workstation. But add just one more diskless
workstation to your first node and server, and you have a
network. The cost of adding workstations is relatively low,
considering the amount of additional computing power they give
you.
 
 
How They Work
A network of workstations is comparable to a multiuser computer
system. In the old-style "time-sharing" setting, you bought a
computer with a multiuser operating system, such as Unix, and
connected dumb terminals to it, using serial connections at
perhaps 9600 bps (roughly 1000 bytes per second).
 
On a workstation network, the central computer (or file server)
generally also runs Unix, but it tends to have more disk storage
than the usual departmental computer. The workstations, instead
of being simple terminals, are computers running Unix themselves.
Typically, they connect to the server through Ethernet. They
communicate at 10 megabits per second (roughly 1 megabyte per
second) using TCP/IP protocols. TCP/IP is the de facto industry
standard for Unix networking, but it is also the basis for
networks on other operating systems.
 
How can a diskless workstation boot up Unix without a disk? The
basic startup software is in ROM. When the workstation is powered
up, the ROM-based software identifies itself to the file server
and requests a file transfer (of the Unix kernel) to its local
RAM storage. From then on, you're working with the network,
running Unix locally and transferring files transparently as
needed -- at speeds higher than those of typical PC hard disk
drives. And since each workstation on a network is itself a
computer, running a compute-bound task on one node won't slow the
others down.
 
 
Not Your Ordinary PC
The bare minimum workstation, then, is entirely diskless. The
most inexpensive one I am aware of is the Sony NWS-711. It is
based on a Motorola 68020 CPU and a 68881 FPU, both running at
16.67 MHz, for a claimed 2.3-million-instruction-per-second
processing power. It has 4 megabytes of memory and a 15-inch
monochrome monitor with 816- by 1024-pixel resolution (it's a
"portrait mode" monitor; the screen is configured like a vertical
sheet of paper). The 711 lists for just $3700, which includes
Unix as well as C, Pascal, and FORTRAN compilers.
 
Apart from being a diskless workstation, the 711 can also be used
as an X Window terminal. In fact, since it has no disk, it looks
like a graphics terminal, but, of course, it is much more
powerful. (For more information, contact Sony Microsystems Co.,
1049 Elwell Court, Palo Alto, CA 94303, (415) 965-4492.)
 
In compute-happy environments, such as semiconductor design, you
might see a dataless workstation. It has its own disk drive -- up
to 180 megabytes -- but, since so much system software and swap
space is needed on the disk, all applications and user files
reside on the server. The local disk drive merely keeps the
system going by keeping memory paging local.
 
 
X Marks the Spot
Ethernet and TCP/IP are the low-level links common to most Unix
networks, and the X Window System is the common base for user and
application programs. X Window (as it is almost universally
called) was developed at MIT with assistance and support from
Digital Equipment Corp. (DEC) and IBM. It's not public domain
code, but it is publicly available and free for the asking.
 
Because TCP/IP is a set of network protocols that are transparent
to the operating system, X Window is a network-transparent
windowing system. This has several meanings, all of them good. X
Window is not tied to any given network protocols, so it is just
as happy running on DECnet as it is on TCP/IP. This means you can
run applications on any machine on your network and control them
all from individual windows on your terminal. Note that I said
"machines," not "Unix machines." They don't all have to be made
by the same manufacturer, or even have to be running the same
operating system. They just have to be in your network and
running X Window.
 
X Window is pretty much hardware independent at the user's
graphical-display end. This means that if you're running an
application on a verticalscreen monochrome display this week, you
can run it on a horizontal-screen 24bit color workstation next
week with no problems. What all this means is that companies can
now design their computing environments around their users'
needs, not around the current offerings of a particular
manufacturer. The phrase "heterogeneous network" is usually used
here by industry reporters, although it sounds too clinical for
my taste.
 
 
Getting GUI
Although many people are happy to run xterm, the X Window
Unix-compatible terminal emulator, X Window is not really a
graphical user interface. It does make a terrific basis for one,
however, and any GUI written to run on X Window will be highly
portable as a result. This is the theory behind the current
industry struggle between Open Look (a GUI promoted by Sun, AT&T,
and Unix International [UI]) and Motif (promoted by the Open
Software Foundation [OSF]). Both of these will be available
widely and inexpensively, to the ultimate benefit of users. Of
course, every layer of software that you add increases not only
your productivity but also your system's complexity and its need
for additional disk space and CPU power. But then, that's part of
the game: If you want to work with the state of the art, you're
going to have to pay for it.
 
If you don't want to get caught between OSF and UI, you might
want to look into X.Desktop, a Macintosh-like, icon-based X
Window user interface from IXI Ltd. of Cambridge, England.
X.Desktop is an intuitive interface that lets you bypass many
typical Unix system commands; it will support both Motif and Open
Look styles in the future. It can be obtained in the U.S. from
Unipress Software (Edison, NJ). X.Desktop has been adopted by
companies such as Locus Computing, Motorola, NCR, Uniplex, and
The Santa Cruz Operation (which is including X.Desktop as part of
its Open Desktop product).
 
In fact, if you really get hooked on X Window and don't have a
network, you can still run X Window applications on a single
machine. The system simply uses Unix interprocess communications
instead of network protocols -- more proof that programmers are
truly happiest when they're talking to themselves.
 
 
You Also Need Files
So you have portable industry-standard protocols, windowing, and
user interfaces. What's left? How about a way of hooking
networked machines together so that you can not only transfer
files, but mount an entire file system from a remote machine onto
your local workstation and access it transparently? That's the
Network File System, developed at Sun Microsystems in 1984 (not
at Berkeley, as I mistakenly wrote in BYTE in May). NFS generally
uses UDP/IP, a faster (but technically less reliable) set of
protocols than TCP/IP.
 
NFS, like X Window, is portable and publicly available, as well
as user- and protocol-transparent. By now, you can guess what's
coming: "These factors have led to its becoming an industry
standard." And, as a standard, NFS is another piece of software
that is found on almost every Unix network. Since users no longer
have to worry about where their files reside, it's only the
administrators who have headaches. (Just keeping track of user
log-ins and machines on a network can be a major task.)
 
The real beauty of NFS is that it is not tied irrevocably to
Unix. In fact, machines running MS-DOS, VMS, and IBM VM have all
been placed happily in NFS networks, as with X Window. Getting
these disparate systems to share files transparently is a magic
trick, indeed. By comparison, LANs that work only with DOS
machines and nothing else don't seem very sophisticated at all.
 
Since the Unix kernel itself is just another file, there's no
reason why a diskless Sun workstation couldn't boot up by
requesting its kernel file from a DEC server. And, in fact, this
kind of thing happens every day. This shows the essential nature
of today's networks: They stand apart from any quibbling over
"small" details like machine architecture, byte ordering, the
operating system, or even the network protocols themselves. A
properly designed industrystandard network will simply accept any
and all of these, so that users can have their favorite hardware
as well as their favorite software. After all, making users happy
is the name of the game!
 
                              --- David Fiedler
 
 
Editor's Note: David Fiedler is publisher of the Unix Video
Quarterly and the journal Root, and is coauthor of the book Unix
System Administration. He can be reached on BIX as "fiedler."
 
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
