DATA STORA

GE

OBJECTIVEOBJECTIVE

At the end of this session the students should At the end of this session the students should be able to:be able to:

Define the terms Primary and Secondary Define the terms Primary and Secondary storagestorage

Differentiate between Primary and Differentiate between Primary and Secondary StorageSecondary Storage

Illustrate how data flows between primary Illustrate how data flows between primary and secondary storageand secondary storage

  

KEY WORDSKEY WORDS

Primary storagePrimary storageSecondary storageSecondary storage Immediate Access Store/Internal MemoryImmediate Access Store/Internal MemoryAuxilliary/Backing Storage/External Auxilliary/Backing Storage/External

MemoryMemory

Can you identify Can you identify the main the main

classifications classifications of Storage?of Storage?

Storage has been divided into: Storage has been divided into: - Primary storage: DaPrimary storage: Data that is currently being ta that is currently being

used is held in Main Mused is held in Main Memory. emory. - Primary storage is also referred to as Primary storage is also referred to as

Immediate Access Store (IMAS)/Internal Immediate Access Store (IMAS)/Internal memory.memory.

- Secondary storage: also known as Auxillary - Secondary storage: also known as Auxillary or Backing storage/ External Memory, or Backing storage/ External Memory, holds holds data permanently for later use.data permanently for later use.

HERE’S The Answer!HERE’S The Answer!

Home-WorkHome-Work1. The company Sarah works for is interested in purchasing storage for her computer.

She has to save data on a daily basis and the cost of storage must be affordable.

(A) What type of storage will you recommend?

(B) Give ONE advantage of primary storage over secondary storage

(C) List Two other terms that are used to refer to primary storage and two terms that are used to refer to secondary storage.

2. What are the TWO main components of primary storage?

3. What is the function of the TWO components?

IT PORTFOLIO IT PORTFOLIO Produce a table in MS Word 2007 to show the differences between Primary Storage Produce a table in MS Word 2007 to show the differences between Primary Storage

and Secondary Storage w.r.t. Capacity, Cost, Function, Portability and Speedand Secondary Storage w.r.t. Capacity, Cost, Function, Portability and Speed   

  

OBJECTIVESOBJECTIVESThe student should be able to:The student should be able to:•State the main components of primary State the main components of primary storage.storage.•Explain the function of RAM and ROMExplain the function of RAM and ROM•Explain the difference between RAM and Explain the difference between RAM and ROMROM

Primary Storage comprises Primary Storage comprises of:of:

RAMRAM (Random Access Memory) (Random Access Memory)ROMROM (Read Only Memory) (Read Only Memory)

To see a photo of a RAM chip: http://community.webshots.com/photo/fullsize/2175072340017373952vtTXtM

RAM & ROM CHIPSRAM & ROM CHIPS

RAM memory moduleROM CHIP

CAN YOU IDENTIFY AT LEAST TWO

DIFFERENCES BETWEEN RAM &

ROM???

HOW IS RAM DIFFERENT FROM ROM??HOW IS RAM DIFFERENT FROM ROM??

RANDOM ACCESS MEMORY (RAM)

RAM is immediately available to the processor and holds data and instructions temporarily, while processing takes place.

RAM is volatile meaning the data can be changed and all information is lost when the computer is switched off.

READ ONLY MEMORY READ ONLY MEMORY (ROM)(ROM)

ROM chips hold programs (data and ROM chips hold programs (data and instructions) necessary for starting the instructions) necessary for starting the computer when it is switched on. computer when it is switched on.

The information is fixed The information is fixed at the time of at the time of manufacturemanufacture. .

ROM is non-volatile- information stored on ROM is non-volatile- information stored on ROM is permanent and cannot be deleted but ROM is permanent and cannot be deleted but can only be accessed or read. Its main use can only be accessed or read. Its main use lies in the distribution of software (that lies in the distribution of software (that doesn’t need frequent updating).doesn’t need frequent updating).

STUDENT ACTIVITYSTUDENT ACTIVITY

Use the terms to draw a diagram that show Use the terms to draw a diagram that show how data flows in the computer. Explain how how data flows in the computer. Explain how the data flows.the data flows.

RAM OUTPUT

DEVICE

INPUT DEVICE

CPU ROM

SECONDARY STORAGE

INPUT DEVICE OUTPUT

DEVICE

CPU

RAM ROM

BACKING STORAGE/SECONDARY STORAGE

Primary Storage

Flow of data in a Computer System

data info

How data Flows in the ComputerHow data Flows in the Computer

1.1. Data is sent to RAM via an input device Data is sent to RAM via an input device

2.2. The data is sent from RAM to the CPU to The data is sent from RAM to the CPU to be processedbe processed

3.3. The processed data (information) is sent The processed data (information) is sent back to RAM from the CPUback to RAM from the CPU

4.4. The processed data is sent from RAM to The processed data is sent from RAM to an output device to be displayedan output device to be displayed

5.5. The data is sent to backing storage for The data is sent to backing storage for later use.later use.

OBJECTIVESOBJECTIVES

At the end of this session the students At the end of this session the students should be able to:should be able to:

State the types of ROM chipsState the types of ROM chipsState how each ROM chip is different from State how each ROM chip is different from

each other or similar to each other each other or similar to each other

There different types of ROM chips:There different types of ROM chips: PROM (Programmable Read Only Memory) - has PROM (Programmable Read Only Memory) - has no no

data locked into it upon manufacturedata locked into it upon manufacture but data can be but data can be locked in place, so that the memory can no longer be locked in place, so that the memory can no longer be changed. Thus, data can be written changed. Thus, data can be written once after once after manufacture.manufacture.

EPROM (Erasable Programmable Read Only Memory) EPROM (Erasable Programmable Read Only Memory) - gets its original data in the same way as the PROM - gets its original data in the same way as the PROM chip does. However, the data can chip does. However, the data can be erased several be erased several timestimes using ultra-violet light. using ultra-violet light.

EEPROM (Electrically Erasable Programmable Read EEPROM (Electrically Erasable Programmable Read Only Memory)- a special type of ROM chip that can be Only Memory)- a special type of ROM chip that can be erased several times by the user by exposing the chip erased several times by the user by exposing the chip to an electrical charge.to an electrical charge.

A A similaritysimilarity amongst all three ROM chips amongst all three ROM chips is they are used in: is they are used in:

Read-Only Mode!

Picture of a PROM chip

OBJECTIVESOBJECTIVESAt the end of this session the students should be At the end of this session the students should be

able to:able to: Explain why a computer represents data in the Explain why a computer represents data in the

form of binaryform of binary Explain the terms related to data storage: bit, Explain the terms related to data storage: bit,

byte, character, wordbyte, character, word Calculate the number of bits and bytes in a Calculate the number of bits and bytes in a

word/sword/s State the different units of storageState the different units of storage

Why the computer stores dataWhy the computer stores data

For processingFor processingTemporarilyTemporarily

using Random Access Memory (RAM)using Random Access Memory (RAM)

For later useFor later usepermanently permanently

using secondary storageusing secondary storage

Computers do not store data the way we see it, but Computers do not store data the way we see it, but in the form of binary digitsin the form of binary digits

Why binary digits?Why binary digits?

The computer is an electronic deviceThe computer is an electronic deviceThe computer is a digital deviceThe computer is a digital device

ElectronicElectronic the computer uses electricity to workthe computer uses electricity to work

DigitalDigital the use of binary digits to store datathe use of binary digits to store data

A computer’s memory is made up of A computer’s memory is made up of bi-bi-stablestable devices (two-state) meaning these devices (two-state) meaning these components can be set in one of two components can be set in one of two states, represented by a 0 or 1 (called a states, represented by a 0 or 1 (called a binary digit). A binary digit). A bitbit is the smallest unit of is the smallest unit of storage in a computer. storage in a computer.

A byte is made up of 8 bits which is one A byte is made up of 8 bits which is one character (letter, digit, symbol andcharacter (letter, digit, symbol and

even a space)even a space)

HOW IS DATA STORED?HOW IS DATA STORED?

WHAT’S GOING ON??WHAT’S GOING ON??

Hi!

Huh??

01000001 01000001

So if a byte is the amount of storage needed to store one character then a computer with 32,000 bytes of memory will be able to store up to 32,000 characters!

QUESTIONS??QUESTIONS??

How many bytes are in How many bytes are in the following?the following?

1.1. Hi!Hi!

2.2. Have fun!Have fun!

3.3. AA

4.4. 99

How many bits are in How many bits are in the following?the following?

1.1. Hi!Hi!

2.2. Have fun!Have fun!

3.3. AA

4.4. 99

HOW IS DATA STORED?HOW IS DATA STORED?

Location: a unit of storage space in Location: a unit of storage space in a computer's main memorya computer's main memory

Address: A number that is assigned Address: A number that is assigned to each location in a computer’s to each location in a computer’s memorymemory

Word: a fixed-sized group of bits that are handled together by the machine.

Word size: The number of bits (in a word)

UNITS OF STORAGE:UNITS OF STORAGE:MEANING OF ACRONYMSMEANING OF ACRONYMS

BIT- BINARY DIGIT ( 1 or a 0)BIT- BINARY DIGIT ( 1 or a 0)

KB- KILOBYTEKB- KILOBYTE

MB-MEGABYTEMB-MEGABYTE

GB- GIGABYTEGB- GIGABYTE

TB- TERABYTETB- TERABYTE

UNITS OF STORAGEUNITS OF STORAGE

1 CHARACTER = 1 BYTE = 8 BITS1 CHARACTER = 1 BYTE = 8 BITS

1KB= 1024 BYTES1KB= 1024 BYTES

1MB= 1024KB1MB= 1024KB

1GB= 1024MB1GB= 1024MB

1TB= 1024GB1TB= 1024GB

HOW IS DATA MEASURED?HOW IS DATA MEASURED?

Can you complete the table below?Can you complete the table below?UNITS OF STORAGEUNITS OF STORAGE 1 GB=1 GB= 1 byte = 1 byte = 1 MB = 1 MB = 1 TB = 1 TB = 1 character =1 character = 1 KB =1 KB =

ANSWERANSWER1 byte (1 character) = 8bits1 byte (1 character) = 8bits1 KB = 1024 bytes1 KB = 1024 bytes1 MB = 1024 KB1 MB = 1024 KB1 GB = 1024 MB1 GB = 1024 MB1 TB = 1024 GB1 TB = 1024 GB

AFLAFLANSWER THE FOLLOWING QUESTIONS:

i. A number that is assigned to each location in memory is called _________

ii. A kilobyte is equivalent to ____ bytes

iii. A unit of storage space in Main Memory is known as a _______

iv. A fixed group of bits that are handled together by the machine is a ______

v. The number of bits in a word is known as a ____________

vi. A device that exists in one of two states is __________

vii. What do the following acronyms mean? GB, TB, KB, MB

viii. Arrange the units of storage in order from highest to lowest: KB, GB, MB, TB, byte

……Secondary Storage…Secondary Storage…

What is the difference between a What is the difference between a storage medium & storage device?storage medium & storage device?

The Storage Medium is the actual material object used for storing the data. Some examples are…

FLOPPY DISKHARD DISKMAGNETIC TAPECDDVDCASSETTE

Storage DEVICEStorage DEVICE

The Storage Device is the equipment that handles the use of the medium. For example…

FLOPPY DISK DRIVE

HARD DISK DRIVE

MAGNETIC TAPE DRIVE

CD-ROM DRIVE

DVD DRIVE

CASSETTE RECORDER/PLAYER

CLASSIFICATION OF STORAGE CLASSIFICATION OF STORAGE MEDIAMEDIA

Storage media can be classified based on:Storage media can be classified based on:

How the data is stored How the data is stored

ORORHow the data is accessedHow the data is accessed

HOW DATA IS STOREDHOW DATA IS STORED

Data can be stored using one of the Data can be stored using one of the following methods:following methods:

- MagneticMagnetic- OpticalOptical- ElectricalElectrical

TYPES OF ACCESS TO DATATYPES OF ACCESS TO DATA

Storage Media can offer either:Storage Media can offer either:- Serial Access orSerial Access or- Direct Access to dataDirect Access to data

DIRECT ACCESSDIRECT ACCESS

A method for retrieving or storing data in A method for retrieving or storing data in which the data (record) is identified by which the data (record) is identified by the position of the record in the file. The the position of the record in the file. The record is accessed directly (non-record is accessed directly (non-sequentially). Direct Access is also called sequentially). Direct Access is also called Random Access.Random Access.

SERIAL ACCESSSERIAL ACCESS

Serial Access is where the records are Serial Access is where the records are accessed in the order it was stored. accessed in the order it was stored. Hence, records are stored in sequential Hence, records are stored in sequential order and the search for a record is order and the search for a record is conducted from the beginning of the file conducted from the beginning of the file until the desired record is reached.until the desired record is reached.

SECONDARY STORAGE:SECONDARY STORAGE:MAGNETIC MEDIAMAGNETIC MEDIA

Types of Magnetic Media:

Hard diskHard disk

Floppy diskFloppy disk

Magnetic TapeMagnetic Tape

CassetteCassette

MAGNETIC DISK

TYPE OF ACCESSTYPE OF ACCESS

MAGNETIC MEDIA TYPE OF ACCESS

FLOPPY DISK DIRECT

HARD DISK DIRECT

MAGNETIC TAPE SERIAL

CASSETTE SERIAL

MAGNETIC DISKMAGNETIC DISK

The data is laid out on concentric tracks The data is laid out on concentric tracks on the surface of a flat disk. Data is stored on the surface of a flat disk. Data is stored as magnetized spots on the surface of the as magnetized spots on the surface of the disk.disk.

WHAT ARE THE PARTS OF A WHAT ARE THE PARTS OF A MAGNETIC DISK???MAGNETIC DISK???

SECTORSSECTORS

TRACKSTRACKS

CYLINDERSCYLINDERS

Magnetic disks are Magnetic disks are formatted into 3 formatted into 3 areas:areas: What is a:

(i) Sector

(ii) Track

(iii)Cylinder

A Hard Disk LayoutA Hard Disk Layout

A schematic picture of a hard disk.

MAGNETIC TAPEMAGNETIC TAPE

A recording medium consisting of a thin A recording medium consisting of a thin tape with a coating of a fine magnetic tape with a coating of a fine magnetic material, used for recording analogue or material, used for recording analogue or digital data. Data is stored in frames across digital data. Data is stored in frames across the width of the tape. The frames are the width of the tape. The frames are grouped into blocks or records which are grouped into blocks or records which are separated from other blocks by gaps.separated from other blocks by gaps.

MAGNETIC TAPEMAGNETIC TAPE

Magnetic tape is a serial access medium, similar Magnetic tape is a serial access medium, similar to an audio cassette, and so data (like the songs to an audio cassette, and so data (like the songs on a music tape) cannot be quickly located.on a music tape) cannot be quickly located.

However large amounts of information can be However large amounts of information can be stored within magnetic tape. Due to this fact, stored within magnetic tape. Due to this fact, magnetic tapes are used for the regular backing magnetic tapes are used for the regular backing up of hard disksup of hard disks

QUESTION??QUESTION??Draw a diagram of a floppy disk and a Draw a diagram of a floppy disk and a

hard disk showing how data is storedhard disk showing how data is storedWhat do we mean when we say we are What do we mean when we say we are

formatting a disk?formatting a disk?State TWO differences and Two State TWO differences and Two

similarities between floppy diskettes and similarities between floppy diskettes and hard disk.hard disk.

State ONE similarity and ONE difference State ONE similarity and ONE difference between magnetic tape and magnetic between magnetic tape and magnetic disks.disks.

OPTICAL MEDIAOPTICAL MEDIA

CD-ROMCD-ROMCD-RCD-RCD-RWCD-RWDVDDVDBlu-RayBlu-Ray

OPTICAL MEDIAOPTICAL MEDIA A spiral track is molded onto one side of this disc with tiny A spiral track is molded onto one side of this disc with tiny

indentations, which are called pits. indentations, which are called pits.

In a DVD/CD drive the information is read by focusing a In a DVD/CD drive the information is read by focusing a laser beam on this spiral track, and scanning along the laser beam on this spiral track, and scanning along the track at a constant speed. Because the pits scatter some track at a constant speed. Because the pits scatter some of the reflected light from the laser, the returning laser of the reflected light from the laser, the returning laser beam will have a reduced intensity whenever it beam will have a reduced intensity whenever it encounters a pit. encounters a pit.

When the laser light is converted into an electrical signal, When the laser light is converted into an electrical signal, the drive can interpret the pattern of pits as binary the drive can interpret the pattern of pits as binary information; ones and zeros. information; ones and zeros.

OPTICAL MEDIAOPTICAL MEDIA

The information on such a disc can only be read; no data The information on such a disc can only be read; no data can be added (or deleted) afterwards.can be added (or deleted) afterwards.

TYPE OF ACCESS- OPTICAL TYPE OF ACCESS- OPTICAL MEDIAMEDIA

OPTICAL MEDIA TYPE OF ACCESS

CD DIRECT

DVD DIRECT

QUESTIONS???QUESTIONS???

1.1. List TWO optical devices.List TWO optical devices.

2.2. Briefly explain at least TWO differences Briefly explain at least TWO differences between a CD and a DVD.between a CD and a DVD.

3.3. What is the difference between a DVD and What is the difference between a DVD and DVD-RW?DVD-RW?

4.4. What is a CD used for?What is a CD used for?

ACTIVITY 1:

IDENTIFY EACH STORAGE MEDIUM:

ACTIVITY 2ACTIVITY 2

GROUP THE STORAGE MEDIA (FROM GROUP THE STORAGE MEDIA (FROM ACTIVITY 1) ACCORDING TO THE ACTIVITY 1) ACCORDING TO THE FOLLOWING CLASSIFICATIONS:FOLLOWING CLASSIFICATIONS:

(i) Optical media(i) Optical media

(ii) Magnetic media(ii) Magnetic media

(iii) Electrical(iii) Electrical

ELECTRICAL STORAGE ELECTRICAL STORAGE MEDIAMEDIA

FLASH MEMORY CARDSFLASH MEMORY CARDSFLASH DRIVEFLASH DRIVE

FLASH TECHNOLOGYFLASH TECHNOLOGY

Flash memoryFlash memory is a non-volatile computer is a non-volatile computer storage chip that can be electrically erased storage chip that can be electrically erased and reprogrammed. It was developed from and reprogrammed. It was developed from EEPROM (electrically erasable program EEPROM (electrically erasable program mable read-only memory) technologymable read-only memory) technology

FLASH MEMORY- CardsFLASH MEMORY- Cards

Based on EEPROM technologyBased on EEPROM technologyFlash memory is non-volatileFlash memory is non-volatilePortablePortableHigh Data Capacity- 512MB to 2GBHigh Data Capacity- 512MB to 2GBHigh data transfer speed/direct accessHigh data transfer speed/direct accessFlash memory cards are used in digital Flash memory cards are used in digital

cameras, cell phones and video gamescameras, cell phones and video games

FLASH DRIVEFLASH DRIVE

A Flash memory storage deviceA Flash memory storage deviceFast/direct accessFast/direct accessLarge storage capacityLarge storage capacityPortablePortable

STORAGE MEDIA’S USESTORAGE MEDIA’S USE

STORAGE MEDIA DESCRIPTION (USE & TYPE OF DATA IT STORES)

FLOPPY DISK STORES TEXTUAL DATA

HARD DISK BACK-UP DATA:TEXT, VIDEO, AUDIO

CD SOFTWARE DISTRIBUTION & MUSIC. CAN STORE TEXT, AUDIO & A VIDEO CLIP

DVD MOVIES- AUDIO AND VIDEO

MAGNETIC TAPE BACK-UP LARGE AMOUNTS OF DATA

CASSETTES AUDIO

MEMORY STICK BACK-UP DATA

COMPLETE THE TABLECOMPLETE THE TABLESTORAGE STORAGE CAPACITYCAPACITY

PORTABILITYPORTABILITY STORAGE STORAGE METHODMETHOD

METHOD METHOD OF ACCESSOF ACCESS

Magnetic Magnetic TapeTape

Floppy Floppy diskdisk

Hard diskHard disk

Compact Compact DiscDisc

DVDDVD

Flash Flash DrivesDrives

STORAGE MEDIUM

CAPACITYCAPACITY PORTABILITYPORTABILITY STORAGE STORAGE METHODMETHOD

METHOD OF METHOD OF ACCESSACCESS

Magnetic Magnetic TapeTape

2GB-1.6TB2GB-1.6TB PortablePortable MAGNETICMAGNETIC SERIALSERIAL

Floppy diskFloppy disk 1.44 MB1.44 MB PortablePortable MAGNETICMAGNETIC DIRECTDIRECT

Hard diskHard disk 40 GB– 1TB40 GB– 1TB Usually fixed Usually fixed but removablebut removable

MAGNETICMAGNETIC DIRECTDIRECT

Compact Compact DiscDisc

650 MB- 650 MB- 800MB800MB

PortablePortable OPTICALOPTICAL DIRECTDIRECT

DVDDVD 4.7 GB-17GB4.7 GB-17GB PortablePortable OPTICALOPTICAL DIRECTDIRECT

Flash DrivesFlash Drives 128 MB – 128 MB – 16GB16GB

PortablePortableELECTRICAL ELECTRICAL FLASH MEMORY FLASH MEMORY (EEPROM)(EEPROM)

DIRECTDIRECT

GAMESGAMES

http://www.teacherxpress.com/f.php?gid=35&id=20http://www.teacherxpress.com/f.php?gid=35&id=20

HANGMANHANGMAN SPOT THE TEACHERSPOT THE TEACHER BREAKOUTBREAKOUT DRAG AND DROP (RAM, ROM,BITS AND BYTES, DRAG AND DROP (RAM, ROM,BITS AND BYTES,

FLOPPIES, HARD DISK, STORAGE DEVICES) FLOPPIES, HARD DISK, STORAGE DEVICES) FLASH CARDSFLASH CARDS TRUE/FALSETRUE/FALSE