The Gazette 1990

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GAZETTE JULY/AUGUST 1990
How do the two operating systems
compare from a performance point
of view? To explain this we will use
an example of someone typing a
document on both systems.
As the typist presses each key,
the computer is continually moni-
toring the keyboard to see what key
the typist presses, so when the
typist presses " W " , the computer
interprets this and then displays a
" W " on the screen, and so on for
all letters in the document. The
computer also watches for when
the typist reaches the end of a line
(by counting the number of letters
on a line) and automatically
reformats so that the start of the
word goes onto a new line. A lot
more work is done by the computer
as the typist corrects mistakes,
displays different parts of the docu-
ment and formats the document.
Now let's assume that there are
five typists.
On a UNIX computer all this work
is done by the one computer. This
means that: —
there are five copies of the word
processing program in memory;
there are five different docu-
ments in memory;
the computer cycles to each
typist and gives each a slice of
time to keep his screen up to
date with his typing;
the limiting factor is the memory
size of the computer and the
number of typists.
On a network each typist has a
whole PC to himself. This means
t h a t : -
there is less work being done
collectively by each PC;
the processing is going on inde-
pendently and simultaneously;
there is no delay on one computer
keeping all the other typist's
screens up to date as each PC
keeps its own screen up to date;
the limiting factor for each typist
is the speed of his PC;
What happens when the typist
decides to write the document to
disk?
Here both systems have approxi-
mately the same amount of work
to do. However, new limiting
factors come into play. On a
network it is the speed with which
the PCs can send data to the file
server and the speed with which
the file server can write to disk. On
the UNIX computer the limiting
factor is the speed with which it
can write to disk and the number
of users using the computer re-
quiring their screens to be
refreshed.
One person writing to disk on a
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network will not affect the
typing on another person's PC.
However, on a UNIX system the
computer has to wait for the
physical movements of writing
to disk, which is slower than
keeping screen displays refresh-
ed so there is a degradation in
performance whenever there is
disk reading and writing on a
UNIX computer.
Ask anyone which is the best
word processor and the answer will
invariably be his own. It is the same
with operating systems. UNIX
users swear by UNIX and
networkers do likewise. However,
when compa r i ng you must
compare like with like. There is no
point in saying that a particular
network is slow if you have a super
fast file-server and the PCs
attached to it are slow when the
PC's speed is the limiting factor.
Similarly, you cannot say UNIX is
slow if the computer is not
" M y own view is that net-
working is the way to go."
fast enough or there are too many
users competing for the resources
of the one computer.
My own view is that networking
is the way to go. The range of
software is by far the greater and
the economies of scale mean less
expensive software. If the file
server is fast and the PCs are
chosen carefully for their use, the
unit user cost is less. Also you can
build now for a ne twork by
choosing stand-alone PCs and
coping with the integration problem
in the short term. (I have just
ordered a networking system using
a Digital VAX mini computer as a
file server with three 80286 single
floppy workstations).
In a recent article in this Gazette
Mr. Frank Lanigan was very dis-
missive of Networking systems
claiming they were single user in
concept and that everyone using
them acts independently. This is
completely untrue as I am aware of
several firms of solicitors (among
them some of the largest firms in
Dublin) who use networks and use
them very well and efficiently and
are very happy with them. Indeed,
they would be very offended if
anyone thought they experienced
any of the problems outlined by Mr.
Lanigan. On any system, single-
user, networking, UNIX or any other,
you will have chaos if everyone is
allowed to operate in ignorance
without structure and discipline.
When I want legal advice, I go to
my solicitor. When I want account-
ing advice, I go to my accountant.
When I want computing advice I
ask my colleagues, whom I know
to be independent. However, my
experience, shows that less than
2% of solicitors consult with an
independent computer consultant
and that most solicitors choose
their computer systems from re-
commendations by other solicitors.
" . . . less than 2 % of solicitors
consult with an indapandant
computer consultant
This is not entirely wrong, but your
plans for your firm are not neces-
sarily the same as your colleague's
plans for his.
On a recent visit to the Cebit
Computer Fair in Hanover, I was
very interested to learn that the
majority of German lawyers pur-
chasing computer systems (not
simply PCs for word processing)
were going for networking solu-
tions rather than UNIX as they
believe simply that one processor
could not work as fast as several
processors on a network. They are
planning for the day when every
person in the firm will have a PC or
terminal on his desk, from the most
senior partner to the most junior
clerk; when they can take their
work home, to court, to a client or
abroad on a portable PC and simply
report back to base over a modem
whenever necessary. Despite their
high spending power, less than
10% of German lawyers have gone
beyond the PC word processing
stage as yet. However, with the
coming of 1992 and the social
charter, German secretarial costs
are set to rise and as a conse-
quence office automation systems
are becoming more common. The
systems being chosen are on net-
works rather than UNIX.
* Donal O'Loch/ainn has an . in
Computer Science from Trinity College,
Dublin. He is a computer consultant
and specialises in software solutions
for the legal profession. His software
product TOPS Legal is now installed in
20 firms in Ireland. He is M.D. of
TOPSOFT Ltd., Fermoy (025) 32344.
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