Transcript memppt alex

Teacher: Ms. Luce
Name: Alex H.
Date: February 18th 2010
Course: TEJ3M
http://computer.howstuffworks.com/computer-memory4.htm
Memory is Data. Memory can be
stored in devices meaning
programs or data. Memory is
what you save and you can use
later on. There are two types of
main memory that we see in
everyday life on computers.
These are called RAM and ROM.
Also known as Random access
memory and Read-Only memory.
There are many strands that they
branch off to. Memory is also
transferred in different ways and
can be deleted.
Picture of RAM
above
Primary Digital Memory branches off into RAM and
ROM. RAM standing for Random Access Memory for
things such as a Cameras when you are taking off
photos or editing them. RAM is also known as
temporary memory because if you don't save it
somewhere else, the memory in RAM will be deleted
once the computer is turned off. ROM is Read Only
Memory and it is for programs or data that the
computer needs to program or function properly. It is
also called Permanent data because it is any
instructions or data that determines how a computer
boots or functions.
RAM is Random Access Memory, It
is temporary memory in a computer.
RAM is slots and the OS(Operating
system) is loaded to RAM when the
PC is turned on. An example of RAM
is when you are taking data from a
camera and you load it to see the
pictures and you save it in RAM.
Once you turn off the computer, all
the memory in RAM is deleted. That
is why you should store data on
USBs or Cds so you do not lose your
information.
There are many different types of
RAM but two main types are SRAM
and DRAM. SRAM stands for Static
Random Access Memory, It is more
expensive than DRAM which is
Dynamic Random Access Memory.
SRAM is more of a single chip
because you really don't need that
much of it. SRAM is more
expensive than DRAM because
SRAM does not need to be
periodically refreshed every few
milliseconds such as DRAM needs
to be. Other examples of RAM are
SDRAM SDRAM RDRAM DDRRAMSDRAM RDRAM SLDRAM.
An Example of DRAM
above
DRAM is very simplistic
compared to SRAM since it
has to be refreshed
constantly, only one
transistor and a capacitor
is needed.
The information leaks and
needs to be read and
written every few
milliseconds(refreshing the
memory).
How SRAM works is
that it stores each bit
as a voltage, each
memory cell requires 6
transistors therefore
giving low chip density
and high speed.
ROM is Read-Only Memory, also known as
permanent memory. It is permanent because it is
data or programs that determine how the computer
boots and functions. It is a chip and it can be either a
square or rectangular. The memory in ROM is
unchangeable or requires a special operation to
change it. ROM uses a diode to connect the lines if
the value is 1. If the value is 0, then the lines are not
connected at all.
One type of ROM is PROM which is
Programmable Read-Only memory.
Blank PROM chips are cheap and
can be bought and programmed
with a special tool called a
programmer, hence the name.
Every intersection of a column and
row in a PROM chip has a fuse
connecting them. A charge sent
through a column will pass through
the fuse in a cell to a grounded row
indicating a value of 1. Since all of
the cells have a fuse, when the
PROM is blank the initial state is all
1's, to make it zero, you use the
programmer to send a calculated
current to the cell. PROM can only
be programmed once.
Another type is EEPROM, also
known as Electrically erasable
programmable read-only memory.
Unlike EPROM this chip does not
need to be removed to be rewritten.
All the data does not need to be
erased to change a part of the
memory. Changing the contents
does not require additional dedicated
equipment. you can return the
electrons in the cells of an EEPROM
to normal with an electrical field to
each cell. By doing this, you can
erase the cells which u want to
rewrite. EEPROMS are changed 1
byte a time which is really slow.
Another type of ROM is EPROM it is also
known as Erasable programmable readonly memory. They are cheap per chip
but the cost builds up. Unlike ROM,
EPROM can be programmed many
times, hence the name. Erasing an
EPROM requires a special tool that emits
a specific amount of UV light. The cell at
each intersection has two transistors. The
two transistors are separated by a thin
oxide layer. One of the transistors is
known as the floating gate and the other
as the control gate. The floating gate's
only link to the row is through the control
gate. While the link is connected, the
value is one to change it to 1 you must
use Fowler-Nordheim tunnelling This is a
process where alter the placement of
electrons in the floating gate. A blank
EPROM has all the values as 0.
The last of the 5 basic ROMs
is Flash Memory, it is a type
of EEPROM but it is faster
because it writes data in
blocks which are bigger in
which the EEPROM does it
in. It uses in-circuit wiring to
erase by using an electrical
field. Some examples of
Flash Memory are a memory
stick, Memory cards, Your
computers BIOS chip etc.
Memory address is when a
byte has an address according
to its memory. That place
where the byte is stored is
called the memory address. At
that address is the information
that the CPU needs for
whatever reason.
Memory size is essential for how much
data or programs you would like to store
into your device, be it your P.C, phone or
even MP3. Most people round our
numbers such as a megabyte to 1million
bytes because the actual size is close to
1 million. Here are the rounded numbers
of the memory sizes.
As you can see they all end with a 0,
therefore they are all rounded. They
are rounded because it is put in easier
terms and is calculated easier. But
there are actual sizes and they are a
little bit more than the actual sizes
because the actual sizes were rounded
down.
-Byte- 8 bits-smallest piece of memory
kilo- 1 024
(also nibble= 1/2 byte (4 bits)
Mega- 1 048 576
word= 2 bytes(16 bits))
Giga- 1 073 741 824
Kilo-1000
Tera- 1 099 511 627 776
Mega- 1,000,000
Giga- 1,000,000,000
Tera-1 trillion
peta- 1 125 899 906 842 624
exa- 1 152 921 504 606 846 876
zetta- 1 180 591 620 717 411 303 424
Yotta- 1 208 925 819 614 629 174 706 176
Some examples of devices that store memory are Punch Card
memory, Magnetic Core memory and Semi Conductor memory.
There are many different devices that store memory but these
ones are major memory devices.
Punch Card Memory is pretty
much the title as it is the
process of storing information
but punching holes into a card
in specific locations. Punched
cards were used to input and
output information on the first
generation of computers.
These cars were also used for
storing instructions which
were pretty much the first form
of computers.
Semi Conductor Memory is
used by all digital computers.
This type of memory is based on
integrated circuitry technology.
It is faster and cheaper than
what they used before, core
memory. Semiconductor
memory has latches and the
latches are able to store data for
an indefinite amount of time.
A process called Caching greatly increases the speed of
pulling bits and bytes from memory. When you use a cache,
you must check it to see if what you are looking for is in
there. If it is there it is a cache hit and if not, a cache miss
and the computer has to search the larger area of memory
and it takes a while. There can be plenty layers of cache.
L2 caching is when there are
three layers and the computer
can check those 3 layers. It can
also be called a two-level cache.
It transfers at the speed of a bus.
L1 caching is when the computer
uses the microprocessor. They
build a system directly into the
microprocessor and the memory
transfers at the speed of a
microprocessor and not as slow
as a bus. The microprocessor is
the fastest thing in the computer.
Registers are Small
amounts of memory
attached to the
CPU(Central Processing
Unit). The memory
attached to the CPU is an
essential data for the CPU.
Some Examples are a 32
bit processor and a 64 bit
processor.
Thanx for
watching.
By: Alex Huang