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RAM means random access
memory.
A better name would be
read/write memory.
Ram is VOLATILE, meaning
that when you switch
off, the data it
contains is lost.
There are two main types
of ram, static and
dynamic.
Static ram uses
flip-flops to store
bits, and so consumes
current whether they are
storing a 1 or a 0.
Dynamic ram uses
capacitors to store
charges and use less
power.
However, these stored
charges leak away and
have to be continually
REFRESHED which makes
the circuitry more
complicated.
The 4118 is an 8 bit x1k
static ram having an 8
bit data bus, D0-D7.
Data can be written to,
or read from memory,
depending the state of
the WE pin.
There may be several
memory chips, so only
one is selected at a
time by taking the CS
pin low.
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