Apple IIe - Page 16

16
Apple
lie
Users
Handbook
Bits
&
Bytes
Microprocessor
logic
is
based
upon
the
bit.
A bit is
the
basis
of
all
information
storage
within
the
computer.
A bit consists
of
a
simple
switch
that
can
consist
of
either
of
the
two
binary states,
on
or
off.
Bits
are
often
separated
into
groups
of
eight.
These
groups
of
8
bits
are
known
as a
byte.
A
byte
is
required
to
represent
a
single
character
(i.e.
letter
,
number,
or
symbol).
Generally
,
bytes
are
processed
by
the
computer
in
groups
of
2.
Most
of
the
8-bit
microprocessors
can
only
address
(or
work
directly
with) 65,535
(64K)
bytes at any
one
time
. Even
though
this
number
appears
large,
a
30
page
document
would
fill
this
memory
area.
The
Apple
lie
uses
an
8 bit
microprocessor
.
However
,
due
to
the
usage
of
special
memory
banking
and
switching
techniques,
the
lie
can
address
over
64K
of
memory.
Most
16-bit
microprocessors
can
address
from
65535
to
16
million
bytes
of
memory
.
Moreover
, 16 bit
microprocessors
process
data
at
a
speed
from
2
to
10
times
faster
that
8-b
it
microprocessors
.
The
IBM
Personal
Computer
is
an
example
of
a
computer
that
uses a 16 bit
microprocessor.
ROM
and
RAM
ROM
stands
for
Read-Only
Memory.
ROM
will
hold
the
data
stored
in it
permanently
.
If
the
power
to
the
Apple
is
shut
off,
the
information
stored
in
ROM
will
remain
there
.
As
previously
mentioned,
the
Apple's
BASIC
language
interpreter
is
stored
in
ROM.
RAM
stands
for
Random
Access Memory*. Any
data
stored
in
RAM
is
lost
when
the
Apple's
power
is
shut
off.
When
data
is
*
Random
Access
Memory
is
a
somewhat
misleading
term
to
describe
RAM, as most
memory
(including ROM)
is
randomly
accessed.