There are two main types of computer memory: volatile and non-volatile. Volatile memory, like RAM, loses its stored data when power is removed but is fast, while non-volatile memory, like ROM, retains data without power but is slower. RAM is the primary memory for running programs and comes in types like SDRAM, DDR SDRAM, DDR2 SDRAM, and DDR3 SDRAM that have faster data transfer speeds. Caches and registers are even faster but smaller memory types close to the CPU. Non-volatile memory includes ROM for long-term storage and flash memory for rewritable storage.

2. COMPUTER MEMORY
• In computing memory refers to the physical device used to
store program (sequences of instruction) or data on a
temporary or permanent basis for use in a computer or other
digital electronic device.

3. TYPES OF COMPUTER MEMORY
THERE ARE TWO TYPES OF COMPUTER MEMORY.
1, VOLATILE MEMORY.
2, NON VOLATILE MEMORY.

4. VOLATILE MEMORY
• Volatile memory is a type of storage whose contents are erased when the system's
power is turned off or interrupted. For example, RAM is volatile; meaning users will lose
a document if they do not save their work to a non-volatile classification of memory, such
as a hard drive, before shutting down the computer.
• There are several types of volatile memory
• Ram, cache, register and virtual memory.

5. RAM (RANDOM ACCESS MEMORY)
• Ram is stands for "random access memory". It stores
temporarily information and it is also known short term memory
RAM simply holds data for the processor..

6. TYPES OF RAM
There are four types of ram which are shown below:
1. SD RAM
2. DDR SDRAM
3. DDR2 SDRAM
4. DDR3 SDRAM

7. SDRAM, DDR SDRAM
SDRAM: SDRAM stands for synchronous dynamic random access memory. SDRAM is
single data rate meaning that SDRAM can accept one command and transfer one word of
data per clock cycle typical speeds of SDRAM are 100 and 133 mhz.
DDR RAM: DDR SDRAM stands for double data rate synchronous dynamic random
access memory. DDR RAM transfers data twice per clock cycle, hence the name double
data rate. DDR clock speeds range between 200 MHz (DDR-200) and 400 MHz (DDR-
400). DDR-200 transfers 1600 MB/s, while DDR-400 transfers 3200 MB/s.

8. DDR2 SDRAM AND DDR3 SDRAM
DDR2 SDRAM: DDR2 SDRAM stands for double data rate 2 synchronous dynamic random
access memory.DDR2 is twice as fast as DDR which means twice as much data is carried to
the module for each clock cycle. DDR2 speeds range between 400 MHz (DDR2-400) and 800
MHz (DDR2-800). DDR2-400 transfers 3200 MB/s. DDR2-800 transfers 6400 MB/s.
DDR3 SDRAM: So by now after reading the above it is quite obvious what DDR3
SDRAM stands for, double data rate 3 synchronous dynamic random access memory. In
theory DDR3 is supposed to act twice as fast as DDR2 memories. Thus DDR3 speeds
range between 800 MHz (DDR3-800) and 1600 MHz (DDR3-1600). DDR3-800 transfers
6400 MB/s; DDR3-1600 transfers 12800 MB/s.

9. CACHE
• Cache memory, also called CPU memory a computer microprocessor can access more
quickly than it can access regular RAM as the microprocessor processes data, it looks
first in the cache memory and if it finds the data there (from a previous reading of data),
it does not have to do the more time-consuming reading of data from larger memory. It is
small amount of memory and expensive too.

10. REGISTERS
• In computer architecture, a processor register is a small amount of storage available as
part of a digital processor, such as a CPU. Such registers are (typically) addressed by
mechanisms other than main memory and can be accessed faster. It is more expensive
and fastest than cache.

11. TYPES OF REGISTER
THERE ARE TWO TYPES OF REGISTER.
1. MEMORY BUFFER REGISTER
2. MEMORY ADDRESS REGISTER

12. MAR,MDR
• MAR STAND FOR MEMORY ADDRESS
REGISTER
• This register holds the memory addresses of
data and instructions. This register is used to
access data and instructions from memory
during the execution phase of an instruction.
Suppose CPU wants to store some data in
the memory or to read the data from the
memory. It places the address of the-required
memory location in the MAR.
• MEMORY BUFFER REGISTER
• MBR stand for memory buffer register. This
register holds the contents of data or
instruction read from, or written in memory. It
means that this register is used to store
data/instruction coming from the memory or
going to the memory.

13. VIRTUAL MEMORY
• An imaginary memory area supported by some operating systems (for example,
windows but not DOS) in conjunction with the hardware. You can think of virtual memory
as an alternate set of memory addresses. Programs use these virtual addresses rather
than real addresses to store instructions and data. When the program is actually
executed, the virtual addresses are converted into real memory addresses.

14. NON VOLATILE MEMORY
• Non-volatile memory is computer memory that can get back stored information even
when not powered.
• There are several type of non-volatile memory.
• Rom , flash memory

15. ROM( READ ONLY MEMORY)
• Rom is stand for “read only memory”.It stores permanently information.It
is known as long term memory.Rom. Contains the programming that
allows your computer to be "booted up" or regenerated each time you
turn it on

16. FLASH MEMORY
• Flash memory is an electronic computer storage medium that can be electrically erased
and reprogrammed it is introduced by toshiba in 1984, flash memory was developed
from EEPROM (electrically erasable programmable read-only memory)

17. TYPES OF ROM(READ ONLINE MEMORY)
THERE ARE THREE TYPES OF ROM…
1. PROM
2. EPROM
3. EEPROM

18. PROM,EPROM AND EEPROM
• PROM: This type of ROM can be re-programmed by using a special device called a PROM
programmer. Generally, a PROM can only be changed/updated once.
• EPROM: This type of ROM can have its contents erased by ultraviolet light and then
reprogrammed by an RPROM programmer. This procedure can be carried out many times;
however, the constant erasing and rewriting will eventually render the chip useless.
• EEPROM: This type of ROM works in a similar way to flash memory in that it can its
contents can be 'flashed' for erasure ad then written to without having to remove the chip
from its environment. EEPROM are used to store a computer system's BIOS, and can
be updated without returning the unit to the factory. In many cases, BIOS updates can
be carried out by computer users wishing a BIOS update.

19. Hard disk, CD-ROMs and flash memory
Ram(Random access memory)
cache
register
As it arrow goes
downward memories
are more efficient
expensive small in
size and faster too .
As it arrow goes upward
memories are more
cheapest and big in size
and slow too.
Memory hierarchy

20. GROUP MEMBERS:
 SHAHBAZ AZEEM (GROUP LEADER)
 SAAD AMIN
 ANAS