A clear and detailed explanation of Memories helps to understand the basics and little complex concepts of memories

1. By
Supriya & Kumari

4. What is memory ?
Computer memory is any physical device capable of storing
information temporarily like RAM (random access memory),
or permanently, like ROM (read-only memory). Memory
devices utilize integrated circuits and are used by
operating systems, software, and hardware.

5. Simple definition:--
The part of a computer in which data or program instructions can
be stored for retrieval.

6. Types of memory:
Primary memory
Cache
ROM
RAM
Secondary memory
Magnetic media
Optic media
Flash memory
Blu-ray disk

7. Primary memory:
Primary memory is
computer memory that is
accessed directly by the CPU.
This includes several types of
memory, such as the
processor cache , system
ROM and RAM.

8. RAM:
 best known form of Computer
Memory.
 Also called MAIN MEMORY.
 Read and write (R/W) memory
 volatile memory, it means
information written to it can
be accessed as long as power
is on.

9. TYPES OF RAM:
Dynamic RAM:
• loses its stored information in
a very short time even when
power supply is on.
• Larger storage capacity in a
single memory.
• cheaper

10. TYPES OF RAM:
Static RAM
• retains stored information
only as long as the power
supply is on.
• costlier and consume more
power.
• higher speed than D-RAMs
• represents a single bit of
data.

11. Question:

12. Cache Memory:
• It also called CPU memory, is high speed SRAM.
• A computer microprocessor can access more quickly than it can
access regular random access memory (RAM).
• Fast access to the instructions increases the overall speed of the
program.
• Primary cache
• Secondary cache
• Stores recent calculated result of system and whenever system
needs it, System can directly fetch the result from cache.

13. ROM:
• ROM stands for Read Only
Memory.
• The memory from which we can
only read but cannot write on it.
• non-volatile
• The information is stored
permanently in such memories
during manufacture.
• stores instructions that are
required to start a computer.

14. TYPES OF ROM:
• Programmable Read-Only
Memory (PROM)
• Erasable Programmable Read-
Only Memory (EPROM)
• Electrically Erasable
Programmable Read-Only
Memory (EEPROM)

15. Which is faster?

16. SECONDARY MEMORY:
• programs and data are kept on a long-term basis
• non-volatile
• allows a user to store data that may be instantly and easily
retrieved, transported and used by applications and services

17. Examples of secondary memory:

18. TYPES OF SECONDARY MEMORY:
• Magnetic media
• Optic media

19. OPTIC MEDIA DEVICES:
• storage of data on an optically readable medium
• data or information is read or written using a laser beam.
• low cost and high data storage capacity
• EX: CD, DVD, WORM(write-once read-many )

21. Magnetic media:
• uses different patterns of magnetisation in a magnetisable material
to store data
• a form of non-volatile memory.
• storage of data on a magnetized medium.
• EX: Floppy disk, hard disk, magnetic tape

24. LOCAL DISK:
• A local drive or local disk is a hard drive
• physically installed inside of or connected to your computer

25. VIRTUALMEMORY:
• Virtual memory is a memory that appears to exist as main storage
although most of it is supported by data held in secondary
storage, transfer between the two being made automatically as
required.

27. Cloud Memory:
• Cloud storage is a service
model in which data is
maintained, managed, backed
up remotely and made
available to users over a
network (typically the
Internet)
• EX: Google cloud
• Cloud storage is actually a
server at which other
computers save their files.

28. ACCESS Methods:
• RAM -Random Access Memory
• SAM -Sequential Access Memory
• DAM -Direct Access Memory

29. RAM:
• access to any memory cell can be done directly
• If the data is not at the current location, RAM data can be accessed
in any order.
SAM:
• stores data as a series of memory cells that can only be accessed
sequentially
• If the data is not at the current location, each memory cell is
checked until the needed data is found

30. DAM:
• a method that allows an input/output (I/O) device to send or
receive data directly to or from the main memory
• transfer data directly to or from memory without having each byte
(or word) handled by the processor.
• high transfer rates, fewer CPU cycles for each transfer.
• more expensive system
DMA CONTROLLER

31. ***************
• “The first practical form of random-access memory was the
Williams tube starting in 1947. It stored data as electrically
charged spots on the face of a cathode ray tube. Since the electron
beam of the CRT could read and write the spots on the tube in any
order, memory was random access. “