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thO
gonefo~purpoS&
10flT\
for
tho
numtMlfs. words.
ond
oThel'
:nlc.mo·o()fl
VOU
Mlet
Into
tho
CompulOl
You
con
onTO!
dolo
'OV
fYpong
at
Tho
keyboard.
loading 0
~Ie
from 0
d'1Sk.
Of
U$Ing
somo
othO\'
de~ce
(1
ke
0
mouse.
a
graphics 100101.
Of
another
compulOl)
Starting
the
system
Staning 2
computer
brings
alllhe
components
into play. Every lime
you stan your computer, a program in ROM looks for a disk
with
an
operating $}Stem
on
It
in
the
sunup
dri
...
e
An
operating
S)'SIClll is a program that coordill2tes
aaivilies
among
the
memory,
keyboard.
screen,
and
disk It controls
the
way
your
program is
loaded
into memory, the way
the
computer
works
....
'ith
mIa,
the
....
'lIIy
data
is
stored
on
:lI
disk,
and
the way
the
computer
communiates
with
your
primer
2nd
Olhcr peripher.ll devices.
You'll find a more detailed
discussion
of
opclllting systems
near
the
cnd
of
Ibis chapler.
Assuming the RO.\I program finds an operating system,
the
RO.\1
program
then
copies
the
oper.ning
system into RAM
Once
the
opcDting
system is in memory, )'00
can
load
an
application
program
(a program that
applies
the
computer
10
$Orne
partiaJlar
lask, like 'word processing
or
cataloging
data).
Some
applications
are
automatically
loaded
into
RAM
In
other
cases,
you
must
type
a
command
to
I03d
the
program.
The
I03ding
process,
governed
by
Ule
oper.lling
S~lCm,
ukes
3
copy
of
the
progr.;Im
on
disk
3nd
loads
il
into
RAM.
Retrieving
data
from a disk
If you intend
to
work with 3 previously created
me,
you load the file's
data into
RAl\l
by
reu-ieving the dat.'l from the disk
1llc
operating
system
loads
a
copy
of
the
data into memory, For
example,
3fter
loading
a
word
processing program, you
C3n
then
load
In
a letter
you
creatc<! in 3n carlier session.
Once
the ICllcr is in
RAM,
you can
see
it
on
the screcn. Diffcrent programs rctrievc
and
save
data in
different
ways. '!lle important thing is that all offcr
thc
retrieve
and
savc
functions. See Figure 4-5,
How
11
WOfks
65
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