VECTOR
GRAPmC,
INC.
Software
falls
into
two
categories. The first, applications
~oftware,
includes
word-processing
programs, accounting and inventory packages, and any other
editing
or
data
proceSSing
packages
you
may
purchase. The second, system
sQftware,
provides
a framework of instructions inside which the computer can
function.
The
combination
of
all
system
software
on
anyone
computer
is
called
the
operatiDi system.
What
is
an
Qoeratlqt
Sptem?
vn-4
In
order
to
control what is going
on
inside
the
computer, an operating system
combines the skills of translator,
switchboard
operator,
and
bookkeeper.
It
begins
by "translating" the
letters
and numbers entered from the keyboard into
instructions
that
the computer can read. Next,
it
looks up
the
right
circuits
along which
to
send
the
translated messages, like an old-fashioned switchboard
operator,
and
relays
commands
to
the
microprocessor,
which
acts
on
its
instructions.
Once
the
information
has
been
processed,
the
right
files
are
pulled out of
mass memory by
the
"bookkeeper"
of
the
system,
updated
with
the
new
information, and returned
to
storage so
that
they can be found and used again.
It
is important to understand
that
the operating system itself initiates none of
this.
You
control
the
operating
system,
by means
of
commands. The
operating
system Simply
consists
of
instructions
to
the
maChinery
of
the
system.
In the "Stone Age" of microcomputers - the early 1910's -
the
user
had
to
determine and give practically all of
these
electronic
commands
each
time he
or
she wanted
to
use
the
computer.
But today, controlled by the instructions coded in the software,
the
hardware
is
driven
by
the
operating
system
at
what is called a very high level. That
is,
you
merely tell the computer to copy
data
from Disk
A:
to
Disk B:, and
the
operating
system
does
aU
the
rest:
opens and closes
the
exact
circuits
between the two disks, determines where the
data
you
want
begins and ends,
and
tells
you when
it
is
finished.
So
the
operating
system
directs
the
hardware to perform four more or less separate tasks:
•
input,
which in most cases means interpreting the commands (letters
and numbers)
you
enter
at
the keyboard.
•
transfer,
which includes both sending information
from
the keyboard
to
the
RAM
or
the
microprocessor, and also results (output) to the
screen, the printer,
or
to mass m emory.
• prQcessin" which
can
range
from simple displays to complicated
mathematical calculations.
•
permanent
storace, which is done
on
the same
kind
of material used
by a
tape
recorder
(the "mass
memory"
described earlier).
As
with
a tape recorder, this stored information can be
"played" (through a
printer or directly
on
the screen)
at
any time.
7100-0001
9-o1~2
- Rev. A
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