COAET" • r

HELLO, OPERATOR?
(What's an Operating System Anyway?)
by Joe Budge
There is something eerie about
computers nowadays: they're too
quiet. All those brains packed in that
tiny box, but the box just sits there. No
lights flash, no bells ring. The fwapfwap-fwap
of shuffling cards is gone,
along with the whirr and click of flying
tapes. Instead, you can occasionally
hear a muted whisper from the
disk drive. Progress, that password of
the century, has eliminated the army
of lights, buzzers, and switches that
used to make us think of computers
in capital letters. Progress, embodied
in software, turned that cacophony
into a silent hummm Software not
only replaced the barrage of gadgets,
it also supplanted the people those
gadgets were built for. These were the
"computer monitors," the anointed
who told the idiot savant what to do,
when to do it, and how to behave.
They called themselves system operators.
Programmers, showing their
infinite capacity for cleverness, named
the new software packages "operating
systems."
If a central processor is a computer's
heart, then the operating system
is its soul. The operating system determines
every computer's personality.
Give an Apple I 11 the software replica
of the Apple II' s ROM-contained operating
system. Poof! Like a transvestite,
the 111 thinks it's a 11. Feed the 111 its
own SOS, and it regains its own identity.
Commands, capabiities, and restrictions
vary widely between computer
languages, but all of the
behavioral differences come from the
operating system. Take the example
of printers and other plug-in devices.
Apple Pascal always knows where
these goodies are plugged in and how
to work them. In contrast, the BASIC
user must enter slot numbers, initiation
codes, and other technical whatnot.
But the difference lies in the
operating systems, not the languages.
So what is an operating system, anyway?
Back in the old days, at least thirty
years ago, there was no such thing as
an operating system. Computers could
only run one program at a time. T ypically,
only a few input and output
devices were attached to the electronic
brain. The system operator, a
human being, would load a deck of
cards into a card reader, set the
appropriate switches on the computer,
and then punch the "GO" button.
When the program was done, its
output would appear on a printer,
punched tape, or new deck of cards.
The operator would retrieve these
materials, then set up for the next
program. Not only did this make for
long days, but there was so much
running around that the computer sat
idle most of the time. With computers
costing millions of dollars, this was
simply intolerable. Why not include
some extra cards with the program,
some software, to handle the set-up
and link in the next job? Such were the
meager beginnings of the operating
system.
As computers grew in size and
cost, it was discovered that the systems
were still cooling their heels too
often. The computer could compute
about a thousand times faster than
card readers could read, or printers
could print. Well, why not let the computer
work on several things at once?
While one job was printing, a second
could be running, and a third could be
read. Just tack the extra control software
onto the operating system. As a
side benefit, the operating system
learned how to work all of the peri·
pheal, or plug-in, hardware. Programs
didn't have to be as complicated or
detailed as before. Thus, life became
a bit easier for computer programmers.
And then along came disk drives.
All of a sudden, data access could be
fast No one had to go get your card
deck or tape any more; it was already
hooked up to the computer. Since no
one could type as fast as computers
could compute, the gurus let several
people type at once. Not to worry; the
operating system kept track of who
was doing what. They called ths new
operating system feature "timesharing."
Now, microcomputers are kind of
simple-minded, as computers go.
They don't have multiple users, virtual
memory, time sharing, and all the
other fancy features built into large
computers. At least not yet. So the
operating system in a microcomputer
52 Apple Orchard