Author :
Craig
Steiner
Source :
8052.com
Book :
The
8051/8052
Microcontroller:
Architecture,
Assembly
Language,
And
Hardware
Interfacing
(Paperback)
External
RAM
As an
obvious
opposite
of
Internal
RAM,
the 8051
also
supports
what is
called
External
RAM.
As the
name
suggests,
External
RAM is
any
random
access
memory
which is
found
off-chip.
Since
the
memory
is
off-chip
it is
not as
flexible
in terms
of
accessing,
and is
also
slower.
For
example,
to
increment
an
Internal
RAM
location
by 1
requires
only 1
instruction
and 1
instruction
cycle.
To
increment
a 1-byte
value
stored
in
External
RAM
requires
4
instructions
and 7
instruction
cycles.
In this
case,
external
memory
is 7
times
slower!
>>>
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"External
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