( PRIMARY STORAGE)
1. A memory is just like a human brain.
2. It is used to store data and instructions.
3. Memory is the storage area of computer
where all the inputs are stored.
4. Storage device is a hardware component
capable of holding information either
temporarily or permanently.
MEMORY IS PRIMARILY OF TWO
TYPES
−
• PRIMARY STORAGE
• SECONDARY STORAGE
Primary Memory (Main Memory)
• Primary memory holds only those data and
instructions on which the computer is currently
working.
• It is generally made up of semiconductor device.
• Primary storage is consist of a number of storage
location.
• Each location in the storage has a unique number ,
called storage address.
• The data and instruction required to be processed
resides in the main memory. It is divided into two
subcategories RAM and ROM.
Characteristics of primary storage
1. Primary storage mainly used by CPU.
2. As main memory directly connected to the
CPU, so data transfer between CPU and main
memory can be accomplished directly.
3. It has limited storage capacity.
4. It is typically high speed memory and very
costly.
5. It is available in the form of silicon chip.
1. RAM (random access memory).
2. ROM (read only memory).
3. CACHE Memory.
4. Virtual Memory.
1.RAM(Random Access Memory the hardware in
a computing device .
2. RAM is volatile in nature.
3. RAM stores the data purely on temporary basis.
4. RAM is small, both in terms of its physical size
and in the amount of data it can hold.
5. All kinds of displays on the display device
(monitor) will be possible because of RAM.
6. RAM is also referred as read and write
memory of the computer.
7. RAM is a semiconductor memory so it is
very costly.
8. RAM memory has limited space for storing
data.
9. The storage capacity of RAM varies. It is
available in in megabytes (MB) ( like -
521mb) and also in gigabytes (GB) (like-
1GB,2GB, 4GB, 8GB).
RAM
1. Static RAM (SRAM).
2. Dynamic RAM (DRAM).
• The word ‘static” indicates they the memory retains its
contents as long as power remains.
• The static RAM consumes more power.
• Static RAM is more expansive and holds less data than
dynamic RAM.
STATIC RAM
• The term “dynamic” indicated that the must be constantly
refreshed because dynamic RAM loses its stored information
in few milliseconds.
• The dynamic RAM consumes less power and is cheaper than
the static RAM.
DYNAMIC RAM
• Read-only memory, or ROM, is a type of computer storage
containing non-volatile, permanent data that, normally, can
only be read, not written to.
CHARACTERSTICS OF ROM
•
ROM contains the programming that allows a computer to
start up or regenerate each time it is turned on
.
• It consists of small chip located near CPU on the motherboard.
• It is the read only memory i.e. User can only read the
instructions but cannot write into it & it’s nature is non-
volatile i.e. Data does not get erased when the computer is
off .
• The memory organization of ROM is exactly same as RAM.
There are mainly three types of ROM:
1.PROM
(Programmable read-only memory)
2.EPROM
(Erasable programmable read-only memory)
3. EEPROM
(Electrically erasable programmable read-only
memory)
TYPES OF RAM
• Prom is also known as one-time programmable .
• It is non-volatile memory.
• In prom, user can design the instruction only for
once.
• The disadvantage of PROM is that a shock of
electricity can easily cause fuses in ROM to burn
out thereby corrupting the ROM.
• EPROM is designed to overcome the drawback
of PROM.
• EPROM is programmable read-only memory
that can be erased the instructions by using
ultra-violet rays.
• The contents are being written in EPROM, user
cannot read any information.
• EPROM chips are used for research and
development operations.
.
• EEPROM is a type of non-volatile ROM that
enables individual bytes of data to be erased
and reprogrammed.
• EEPROM is usually used to store small amounts
of data in computing and other electronic
devices.
• It's a flash drive memory device designed to
retain the stored information even when the
power is off.
• EEPROM (also called E
2
PROM).
• Cache memory is also known as buffers.
• Its small, fast and expensive type of storage that is placed
between the CPU and the main memory.
• The CPU does not have to use motherboard’s system bus
for data transfer.
• When cache memory becomes full, then the new data
will be stored by replacing some existing information
using a (FIFO) first in first out.
• Cache memory processor provide up to 4MB .
• It allows user to access a large volume of
memory.
• Virtual memory is a storage area that holds the
files on your hard drive for retrieval when a
computer runs out of RAM.
• Virtual memory is a common technique used in
computer’s operating system. It allows user to
access a large volume of memory.
• Temporary storage.
• Store data in MBs.
• Volatile.
• Used in normal
operations.
• Writing data is faster.
• Permanent storage.
• Store data in GBs.
• Non – volatile.
• Used for startup
process of computer.
• Writing data is
slower.
