tures
both
ajoystick
and a true trackball mode.
It
is
available for
about
$60.
ADDITIONAL
MEMORY
FOR
YOUR
COMPUTER
Once
you
know
the type
of
programs and the
software format(s)
you
will
be using,
you
will
need
to
make sure
that
your
computer has
enough
memory
to
hold the program
you
wish
to
load.
Recall
that
your
computer comes
with
a
certain amount
of
memory already in
it
mea-
sured in units called
K (kilobytes). For example,
most Atari
400
computers come
with
16K
of
memory, most
800
systems have 48K, and the
1200XL comes
with
64K
of
memory.
When
you
load larger programs
into
your
com-
puter, such
as
word
processing
or
data base pro-
grams, the
amount
of
memory needed may be
greater than
the
amount
your
computer comes
with.
In such a
case,
you
can
buy
additional
memory for
your
computer
to
enable
you
to
use
these types
of
programs. Extra memory
is
avail-
able
in the form
of
boards
which
hold
additional
memory
chips-the
components
that
allow
the
computer
to
store information in its memory.
Odd
as
it
may seem, there
is
little practical differ-
ence between the capabilities
of
the
newer
64K
system and an
older 48K system, due
to
the
way
in
which
the extra memory
of
the
newer
models
is
utilized. Also, given the large number
of
older
machines in use,
few
software producers
will
write
programs
that
will
work
only
on
64K sys-
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