Tài liệu phục vụ cho học tập nghiên cứu về Memory, tiếng anh chuyên ngành Công nghệ thông tin

Tài liệu phục vụ cho học tập nghiên cứu về Memory, tiếng anh chuyên ngành Công nghệ thông tin Tài liệu phục vụ cho học tập nghiên cứu về Memory, tiếng anh chuyên ngành Công nghệ thông tin Tài liệu phục vụ cho học tập nghiên cứu về Memory, tiếng anh chuyên ngành Công nghệ thông tin

Group 5

Computer

Memories

Members list

Nguyễn Thanh Tùng Nguyễn Lê Thành Tâm Nguyễn Trung Huy

Nguyễn Khánh Duy

Nguyễn Quốc Châu

Nguyễn Thị Mỹ Hạnh Nguyễn Minh Trí

OF MEMORIES

• What is a storage device

and why is it needed?

• An overview of

computer memory.

What is a storage device?

• A storage device is a piece of computer

hardware used for saving, carrying and

pulling out data

• It almost saves all data and applications

in a computer except for hardware

firmware

• It comes in different shapes and sizes

depending on the needs and

functionalities

one of the most popular types

of storage used.

Magnetic Storage Device

uses lasers and lights as its mode of

saving and retrieving data.

Optical Storage Device

is now replacing magnetic storage device as it is economical, more functional and dependable.

Flash Memory Device

is now becoming widespread as

people access data from different

devices.

Online and Cloud

method used by early computers for saving information.

Paper Storage

Types of Storage devices

Why is Storage necessary?

All computers need storage On a modern computer, storage comes in two

forms: temporary and long-term

• Temporary storage: Supplied as memory, or RAM Memory

is where the processor does its work, where programs run, and where information is stored while it’s being worked on

• Long-term storage: Provided by storage media Storage media includes disk drives, flash drives, media cards, and CDs and DVDs

An overview of

computer memory.

• A memory is used to store data and instructions

• The memory is divided into large number of

small parts called cells

 Each location or cell has a unique address,

which varies from zero to memory size minus one

Primary Memory/Main Memory

• Only holds those data and instructions on which the computer is currently working

• Has a limited capacity and data is lost when power is switched off

• Generally made up of semiconductor device

• Divided into two subcategories RAM and ROM

Secondary Memory

• Known as external memory or non-volatile

• Slower than the main memory

• Used for storing data/information permanently

• CPU directly does not access these memories, instead they are accessed via input-output routines

• For example, disk, CD-ROM, DVD, etc

TYPES OF

MEMORIES

• Primary or main memory

• Secondary memory

TYPES OF MEMORIES

Primary Or Main Memory

• Refers to physical memory that is internal to the

computer

• The word “main” is used to distinguish it from external

mass storage devices such as disk drives

• Other terms used to mean main memory include RAM

and primary storage

TYPES OF MEMORIES

Contains information

(data, programs) that the

CPU can exchange

directly

Processing speed

is very fast

Its capacity is not large

Uses semiconductor memory: ROM & RAM

Functions and Features

TYPES OF MEMORIES

Cache Memory

• Cache can be either a reserved section of main

memory or an independent high-speed storage device

• Two types of caching are commonly used in personal

computers: memory caching and disk caching

CPU

Cache Memory

Primary Memory

Secondary Memory

TYPES OF MEMORIES

Memory caching:

• A cache store or RAM cache

• A portion of memory made of high-speed static

RAM (SRAM)

• Effective

TYPES OF MEMORIES

Disk caching:

• Disk caching can dramatically improve

the performance of applications

• Disk caching works under the same principle as memory caching, but instead

of using high-speed SRAM, a disk cache uses conventional main memory

TYPES OF MEMORIES

L1 & L2 cache:

Some memory caches are built into the architecture of microprocessors are often called Level 1 (L1) caches

TYPES OF MEMORIES

L1 & L2 cache:

• Most modern PCs also come with external cache

memory, called Level 2 (L2) caches

 These caches sit between the CPU and the DRAM

 L2 caches are composed of SRAM but they are

much larger

• Higher-end systems and CPUs can include additional

layers of caching, such as L3 and higher

Intel® Pentium® Gold G6500T Processor (4M Cache, 3.50 GHz)

TYPES OF MEMORIES

Cache In Web Browsing:

• Play an important role in the web browsing and

web development experience

 Sometimes referred to as web cache,

http-cache or proxy http-cache

• Web browsers can store frequently accessed data like web pages or images on the hard drive

• Web servers also must clear cache so the most recent version of a website can be displayed to users

TYPES OF MEMORIES

RAM

• Stands for random access memory

• An internal memory of CPU for storing data, program and results of program, while it is being executed

• A read/write memory

• Access time is independent of the address

• A volatile memory, it mean that its content are lost when the power is turned off

TYPES OF MEMORIES

Types of Ram:

DRAM

• Stands for dynamic random access memory

• Dram recharged or refreshed again and

again to maintain its content or data

• Processor cannot access the data or content of dram when it is being refreshed that’s why it is slow

• It is least expensive kind of ram

TYPES OF MEMORIES

SRAM

• Stands for Static Random Access Memory

• Memory retains its content as long as power

is being supplied due to its volatile nature

• Does not need to wait to access data from SRAM during processing

• Normally used to build a very fast memory known as cache memory

• More expensive

TYPES OF MEMORIES

ROM

• A read-only memory (ROM) is a computer memory

on which data has been pre-recorded

• Once data has been written onto a ROM chip, it cannot be removed and can only be read

• Unlike main memory (RAM), ROM retains its contents even when the computer is turned off

• ROM is referred to as being non-volatile, whereas RAM is considered volatile

TYPES OF MEMORIES

Types of Rom:

PROM - Programmable Read

Only Memory

EPROM - Erasable Programmable Read Only Memory

EEPROM -Electrically Erasable Programmable Read Only Memory

• Computer memory that can retrieve stored data after a power supply has been turned off and back on is called non-volatile.

TYPES OF MEMORIES

EEPROM (E2PROM)

• A type of non-volatile memory

• Used in computers, integrated in microcontrollers for smart cards and remote keyless systems, and other electronic devices

• To store relatively small amounts of data by allowing individual bytes to be erased and reprogrammed

TYPES OF MEMORIES

Flash Memory

• A modern type of EEPROM

• Can be erased and rewritten faster than ordinary EEPROM, and newer designs has the feature that is very high endurance (exceeding 1,000,000 cycles)

• Except these types, there are other types of non-volatile memory including optical storage media, such as CD-ROM (analogous to MROM)

TYPES OF MEMORIES

Secondary memory

• Stores your computer's software resources,

including: operating system, programs, and data

• Connected to devices in the form of access.

• Large capacity.

• Slow speed.

• Information is not lost when the power is

turned-off Long term data storage

TYPES OF MEMORIES

Storage capacity and speed:

A storage device’s performance is measured by:

• Capacity: The number of byte of data that a

device can hold

• Access Time: The amount of time, in

milliseconds , it takes the device to begin

reading data

Storage Device

a

TYPES OF MEMORIES

Floppy disk

• Commonly used in storing portable data

• Especially with very old machines often

use a floppy disk to store the operating

system

• Used to start a DOS-based session

 Capacity: 720KB to 1,44MB

 Access time: 100ms

TYPES OF MEMORIES

Hard Drives

Hard drives are "immutable" types of memory that don't lose data when they stop supplying power to them

 Capacity: up to 80GB

 Access time: 6 to 12ms

TYPES OF MEMORIES

An optical drive

A type of device used to read optical discs

 uses a device that emits a laser beam

that hits the surface of the optical disc

 reflected back on the receiver and

decoded into a signal

TYPES OF MEMORIES

Magnetic Memory

Hard Disks

High-speed, high-capacity storage devices

• Contain metal disks called platters

• Contain two or more stacked platters with

read/write heads for each side

• Can be divided into partitions to enable computers

to work with more than one operating system

TYPES OF MEMORIES

Floppy disks

• A disk or diskette is a portable storage

medium

• High-density floppy disks that are

commonly used today store 1,44MB of

data

• Disks work with a disk drive

TYPES OF MEMORIES

Optical Storage Media

• CD-ROM stands for Compact Disc-Read

Only Memory

• CD-ROM drives can not write data discs

• Standard CD storage capacity is about 700

MB, DVD about 17GB

TYPES OF MEMORIES

Optical Storage Media

• Read slower than magnetic disk (hard drive)

• Stores large amount of data in some

formats as much as the entire hard disk

• Reads data by focusing a laser-generated

beam of light on discs surface

TYPES OF MEMORIES

• CD-R stands for Compact

Disc Recordable

• Discs can be read and written

to Discs can only be written

to "once"

• CD-R drivers are capable of

reading and writing data

CD-RW

TYPES OF MEMORIES

DVD-ROM Discs and Drives

• Stands for Digital Video Disc

• Similar to CD-ROM technology

• Capable of storing up to 17GB of data

• The data transfer rate of DVD drivers is

comparable to that of hard disk drives

• DVD-R and DVD-RW drives have the ability

to read/write data

TYPES OF MEMORIES

Soild State Storage Devices

• Use nonvolatile memory chips to retain data

• Do not have moving parts

• They’re small, lightweight, reliable, and

portable

Example: Smart Card, Flash Memory, PC

Card, Memory Stick, Compact Flash Memory,

Micro Drive ”