computer memory description

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Presented By:
RITU KHANDELWAL

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A memory is just like a human brain. Computer memory is the storage space in
computer. It is used to store data and instruction.
In another terms, Computer memory is any physical device capable of storing
information temporarily or permanently.

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Memory
Internal
Processor
Memory
Main
Memory
Secondary
Memory

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A small high speed memory inside the processor. Registers are temporary memory
units that store data and are located in the processor, instead of in RAM, so data
can be accessed and stored faster.
Cache memory is extremely fast memory that is built into a computer’s central
processing unit (CPU). The data that is stored within a cache might be values
that have been computed earlier or duplicates of original values that are stored
elsewhere. The CPU uses cache memory to store instructions that are repeatedly
required to run programs, improving overall system speed.
Temporary storage of instruction and data.
Example: Registers, built-in cache.

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RAM(Random Access Memory) is a part of computer’s Main Memory which is
directly accessible by CPU. RAM is used to Read and Write data into it which is
accessed by CPU randomly. RAM is volatile in nature, it means if the power goes
off, the stored information is lost. RAM is used to store the data that is currently
processed by the CPU. Most of the programs and data that are modifiable are stored
in RAM.
Types of Main Memory
1. RAM (Ramdom Access Memory)
•Volatile.
•Access time for every location is constant and independent ofit’s position
•A temporary storage that can be read from or written into by the user.
2. ROM (Read Only Memory)
•NonVolatile.
•Read Only R memory

7. Static RAM. Static RAM is the full form of SRAM. In this type of RAM, data is stored
using the state of a six transistor memory cell. Static RAM is mostly used as a cache
memory for the processor (CPU).
Dynamic RAM. DRAM stands for Dynamic Random Access Memory. It is a type of
RAM which allows you to stores each bit of data in a separate capacitor within a specific
integrated circuit. Dynamic RAM is a standard computer memory of the many modern
desktop computers. This type of RAM is a volatile memory that needs to be refreshed
with voltage regularly. Else it loses the information stored on it.
Uses of RAM
Here, are important uses of RAM:
RAM is utilized in the computer as a scratchpad, buffer, and main memory.
It offers a fast operating speed.
It is also popular for its compatibility
It offers low power dissipation
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8. SRAM DRAM
SRAM has lower access time, so it is
faster compared to DRAM.
DRAM has higher access time, so it is
slower than SRAM.
SRAM is costlier than DRAM. DRAM costs less compared to SRAM.
SRAM requires a constant power supply,
which means this type of memory which
consumes more power.
DRAM offers reduced power
consumption because the information is
stored in the capacitor.
It is a complex internal circuitry, and it
offers less storage capacity is available
compared to the same physical size of a
DRAM memory chip.
It is the small internal circuitry in the
one-bit memory cell of DRAM. The large
storage capacity is available.
SRAM has a low packaging density. DRAM has a high packaging density.
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ROM stands for Read Only Memory. The memory from which we can only read but cannot
write on it. This type of memory is non-volatile. The information is stored permanently in
such memories during manufacture. A ROM stores such instructions that are required to start
a computer. This operation is referred to as bootstrap.
Advantages of ROM
Non-volatile in nature
Cannot be accidentally changed
Cheaper than RAMs
Easy to test
More reliable than RAMs
Static and do not require refreshing
Contents are always known and can be verified

10.  MROM (Masked ROM)
The very first ROMs were hard-wired devices that contained a pre-programmed set of data or
instructions. These kind of ROMs are known as masked ROMs, which are inexpensive.
 PROM (Programmable Read Only Memory)
PROM is read-only memory that can be modified only once by a user. The user buys a blank
PROM and enters the desired contents using a PROM program. Inside the PROM chip, there
are small fuses which are burnt open during programming. It can be programmed only once and
is not erasable.
 EPROM (Erasable and Programmable Read Only Memory)
EPROM can be erased by exposing it to ultra-violet light for a duration of up to 40 minutes.
Usually, an EPROM eraser achieves this function. During programming, an electrical charge is
trapped in an insulated gate region. For erasing this charge, ultra-violet light is passed through a
quartz crystal window (lid). This exposure to ultra-violet light dissipates the charge. During
normal use, the quartz lid is sealed with a sticker.
 EEPROM (Electrically Erasable and Programmable Read Only Memory)
EEPROM is programmed and erased electrically. It can be erased and reprogrammed about ten
thousand times. In EEPROM, any location can be selectively erased and programmed.
EEPROMs can be erased one byte at a time, rather than erasing the entire chip. Hence, the
process of reprogramming is flexible but slow.
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Imagine that you are using a computer to
write a book report on Tom Sawyer.
Where is the word processor program
that you are running located?
Where are the characters you have
typed?
Brain Storming Question

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Where is the program you are running?
In main memory.
Running programs are always located in
main memory.
A permanent copy will also be in
secondary memory on the hard disk.
Where are the characters you have typed?
In main memory.
When you "save" your document, the
characters are copied to a file on the
hard disk.

13. You cannot store data in the main memory permanently. Firstly, because it is
very expensive and secondary, it’s content are erased when the computer is
turn off.
In order to preserve or save the work which you have done on your computer
you need storage media such as floppy, CD, hard Disk, DVD etc. Secondary
memory is where programs and data are kept on a long-term basis. Common secondary
storage devices are the hard disk and optical disks.
The hard disk has enormous storage capacity compared to main memory.
The hard disk is usually contained inside the case of a computer.
The hard disk is used for long-term storage of programs and data.
Data and programs on the hard disk are organized into files.
A file is a collection of data on the disk that has a name.
External memory or non-volatile.
Backup memory.
These are magnetic and optical memories.
Slower then primary memory.
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Magnetic Tape:
Used for recording analogue or digital data. Transfer data
a bit slower than hard drives. Cheaper.
Floppy Disks :
Very small and portable. Floppy disks comes in 3 sizes: 8-
inches, 5.5-inches and 3.5-inches.
Floppy disk is also called a disk or Diskette, A floppy
disk is a removable storage disk use for storing data. It
is called a floppy disk because the round film inside
the disk plastic shell is flexible. You can take a backup
of any important information from the hard disk in a
floppy. This will present lose of information in the
case hard disk file or is infected with virus. You can
use a floppy disk to store and more data easily from
one PC to another.

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Hard Disk Drive :
HDD is the main, and usually largest data storage device in a computer. It is a non-volatile,
random access digital magnetic data storage device. The data store on a hand disk can
we store a very fast speed. It is a direct address devices. Unlike CD, floppy, etc,
you can’t easily remove a hard disk from a PC.
A hard disk drive is made up of a group of disk or disk platter, piled on tap of one
another in an either dust proof case.
Optical Disk :
Electronic data storage medium. Two main types of optical disks are:
CD’s.
DVD’s.
Flash Drive :
A flash drive is a small external storage device. Flash drives are removable and rewritable
reads and writes to flash memory.

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Say that you have purchased the
game Doom IV and have installed it on
your computer.
The game consists of A program (that
controls the action of the game)
Data (the images and other information)
After installation, where is each of these
parts located in your computer system?
Brain Storming Question

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A program
On the hard disk
Data
On the hard disk
When you play the game, its various parts
are copied from the hard disk into main
memory as needed.

18.  USB flash drives or pen drive Are
Flash memory data storage Device
integrated with a USB interface they
typically small light weight, removable
and rewritable. It is a flash Memory
card that plug into the computer USB
port.
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19.  It is an optical read only memory. The disk is made
up of poly carbonate. It is coated with a material
which change is reflected property when a high
intensity laser beam is focused on it. The coating
material is highly reflecting proper
 when usually
aluminium optical
disk are two types,
namely compact
disk, or worm (write
once & Read many).
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20.  DVD (Digital Video Disk or Digital Versatile Disk)
disk provide more storage capacity than a CD ROM.
The disk used with DVD drives are of the same
diameter and thickness as traditional CDs. Like CDs,
the DVD disk can tolerate dust, Dirt and Finger
Print, DVD are use for storing audio and video
entertainment such movies, videos games and
softwareapplication.
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Which is fastest?
Main memory or
secondary memory?

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Main Memory
Which is fastest?
Main memory or
secondary memory?

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Difference b/w primary
and secondary memory?

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Difference b/w
primary and
secondary
memory?
Primary memory Secondary memory
•Fast
•Expensive
•Low capacity
•Works directly with the
processor
•Slow
•Cheap
•Large capacity
•Not connected directly to
the processor

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