DATA STORAGE

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DATA STORAGE
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OBJECTIVE

• At the end of this session the students should be
  able to
• Define the terms Primary and Secondary storage
• Differentiate between Primary and Secondary
  Storage
• Illustrate how data flows between primary and
  secondary storage
•  

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KEY WORDS

• Primary storage
• Secondary storage
• Immediate Access Store/Internal Memory
• Auxilliary/Backing Storage/External Memory

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Can you identify the main classifications of
Storage?
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HERES The Answer!

• Storage has been divided into
• Primary storage Data that is currently being
  used is held in Main Memory.
• Primary storage is also referred to as Immediate
  Access Store (IMAS)/Internal memory.
• - Secondary storage also known as Auxillary or
  Backing storage/ External Memory, holds data
  permanently for later use.

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Home-Work

• 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
• 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 Speed
•  
•  

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• DIFFERENCES BETWEEN PRIMARY
• SECONDARY MEMORY

CHARACTERISTIC PRIMARY STORAGE SECONDARY STORAGE
CAPACITY Relatively small (generally less than 4GB) Relatively large(generally more than 4GB)
COST Relatively expensive Inexpensive
FUNCTION Stores data instructions being processed by the CPU Stores data and program instructions on a long-term basis
PORTABILITY Not portable Varying degrees of portability
SPEED Fast in relation to processor speed Slow in relation to processor speed
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OBJECTIVES

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

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Primary Storage comprises of

• RAM (Random Access Memory)
• ROM (Read Only Memory)

To see a photo of a RAM chip http//community.web
shots.com/photo/fullsize/2175072340017373952vtTXtM

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RAM ROM CHIPS
ROM CHIP
RAM memory module
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• CAN YOU IDENTIFY AT LEAST TWO DIFFERENCES BETWEEN
  RAM ROM???

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• 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.

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READ ONLY MEMORY (ROM)

• ROM chips hold programs (data and instructions)
  necessary for starting the computer when it is
  switched on.
• The information is fixed at the time of
  manufacture.
• ROM is non-volatile- information stored on ROM is
  permanent and cannot be deleted but can only be
  accessed or read. Its main use lies in the
  distribution of software (that doesnt need
  frequent updating).

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STUDENT ACTIVITY

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

INPUT DEVICE
RAM
OUTPUT DEVICE
CPU
ROM
SECONDARY STORAGE
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Flow of data in a Computer System
CPU
INPUT DEVICE
data
OUTPUT DEVICE
info
RAM
ROM
Primary Storage
BACKING STORAGE/SECONDARY STORAGE
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How data Flows in the Computer

1. Data is sent to RAM via an input device
2. The data is sent from RAM to the CPU to be
   processed
3. The processed data (information) is sent back to
   RAM from the CPU
4. The processed data is sent from RAM to an output
   device to be displayed
5. The data is sent to backing storage for later use.

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OBJECTIVES

• At the end of this session the students should be
  able to
• State the types of ROM chips
• State how each ROM chip is different from each
  other or similar to each other

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There different types of ROM chips

• PROM (Programmable Read Only Memory) - has no
  data locked into it upon manufacture but data can
  be locked in place, so that the memory can no
  longer be changed. Thus, data can be written once
  after manufacture.
• EPROM (Erasable Programmable Read Only Memory) -
  gets its original data in the same way as the
  PROM chip does. However, the data can be erased
  several times using ultra-violet light.
• EEPROM (Electrically Erasable Programmable Read
  Only Memory)- a special type of ROM chip that can
  be erased several times by the user by exposing
  the chip to an electrical charge.

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• A similarity amongst all three ROM chips is they
  are used in
• Read-Only Mode!
• Picture
  of a PROM chip

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OBJECTIVES

• At the end of this session the students should be
  able to
• Explain why a computer represents data in the
  form of binary
• Explain the terms related to data storage bit,
  byte, character, word
• Calculate the number of bits and bytes in a
  word/s
• State the different units of storage

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Why the computer stores data

• For processing
• Temporarily
• using Random Access Memory (RAM)
• For later use
• permanently
• using secondary storage
• Computers do not store data the way we see it,
  but in the form of binary digits

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Why binary digits?

• The computer is an electronic device
• The computer is a digital device
• Electronic
• the computer uses electricity to work
• Digital
• the use of binary digits to store data

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HOW IS DATA STORED?

• A computers memory is made up of bi-stable
  devices (two-state) meaning these components can
  be set in one of two states, represented by a 0
  or 1 (called a binary digit). A bit is the
  smallest unit of storage in a computer.
• A byte is made up of 8 bits which is one
  character (letter, digit, symbol and
• even a space)

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WHATS GOING ON??
Hi! Huh??
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01000001
A
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!
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QUESTIONS??

• How many bytes are in the following?
• Hi!
• Have fun!
• A
• 9

• How many bits are in the following?
• Hi!
• Have fun!
• A
• 9

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HOW IS DATA STORED?

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

Address A number that is assigned to each
location in a computers memory
Word a fixed-sized group of bits that are
handled together by the machine.
Word size The number of bits (in a word)
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UNITS OF STORAGEMEANING OF ACRONYMS

• BIT- BINARY DIGIT ( 1 or a 0)
• KB- KILOBYTE
• MB-MEGABYTE
• GB- GIGABYTE
• TB- TERABYTE

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UNITS OF STORAGE

• 1 CHARACTER 1 BYTE 8 BITS
• 1KB 1024 BYTES
• 1MB 1024KB
• 1GB 1024MB
• 1TB 1024GB

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HOW IS DATA MEASURED?

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

ANSWER 1 byte (1 character) 8bits 1 KB 1024
bytes 1 MB 1024 KB 1 GB 1024 MB 1 TB 1024
GB
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AFL
ANSWER 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
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Secondary Storage
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What is the difference between a storage medium
storage device?

• The Storage Medium is the actual material object
  used for storing the data. Some examples are
• FLOPPY DISK
• HARD DISK
• MAGNETIC TAPE
• CD
• DVD
• CASSETTE

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Storage 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

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CLASSIFICATION OF STORAGE MEDIA

• Storage media can be classified based on
• How the data is stored
• OR
• How the data is accessed

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HOW DATA IS STORED

• Data can be stored using one of the following
  methods
• Magnetic
• Optical
• Electrical

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TYPES OF ACCESS TO DATA

• Storage Media can offer either
• Serial Access or
• Direct Access to data

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DIRECT ACCESS

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

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SERIAL ACCESS

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

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SECONDARY STORAGEMAGNETIC MEDIA

• Types of Magnetic Media
• Hard disk
• Floppy disk
• Magnetic Tape
• Cassette

MAGNETIC DISK
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(No Transcript)
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TYPE OF ACCESS
MAGNETIC MEDIA TYPE OF ACCESS
FLOPPY DISK DIRECT
HARD DISK DIRECT
MAGNETIC TAPE SERIAL
CASSETTE SERIAL
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MAGNETIC DISK

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

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WHAT ARE THE PARTS OF A MAGNETIC DISK???
Magnetic disks are formatted into 3 areas
TRACKS

• What is a
• Sector
• Track
• Cylinder

CYLINDERS

• SECTORS

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A Hard Disk Layout
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A schematic picture of a hard disk.
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MAGNETIC TAPE

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

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MAGNETIC TAPE

• Magnetic tape is a serial access medium, similar
  to an audio cassette, and so data (like the songs
  on a music tape) cannot be quickly located.
• However large amounts of information can be
  stored within magnetic tape. Due to this fact,
  magnetic tapes are used for the regular backing
  up of hard disks

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QUESTION??

• Draw a diagram of a floppy disk and a hard disk
  showing how data is stored
• What do we mean when we say we are formatting a
  disk?
• State TWO differences and Two similarities
  between floppy diskettes and hard disk.
• State ONE similarity and ONE difference between
  magnetic tape and magnetic disks.

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OPTICAL MEDIA

• CD-ROM
• CD-R
• CD-RW
• DVD
• Blu-Ray

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OPTICAL MEDIA

• A spiral track is molded onto one side of this
  disc with tiny indentations, which are called
  pits.
• In a DVD/CD drive the information is read by
  focusing a laser beam on this spiral track, and
  scanning along the track at a constant speed.
  Because the pits scatter some of the reflected
  light from the laser, the returning laser beam
  will have a reduced intensity whenever it
  encounters a pit.
• When the laser light is converted into an
  electrical signal, the drive can interpret the
  pattern of pits as binary information ones and
  zeros.

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OPTICAL MEDIA

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

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TYPE OF ACCESS- OPTICAL MEDIA
OPTICAL MEDIA TYPE OF ACCESS
CD DIRECT
DVD DIRECT
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QUESTIONS???

1. List TWO optical devices.
2. Briefly explain at least TWO differences between
   a CD and a DVD.
3. What is the difference between a DVD and DVD-RW?
4. What is a CD used for?

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ACTIVITY 1 IDENTIFY EACH STORAGE MEDIUM
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ACTIVITY 2

• GROUP THE STORAGE MEDIA (FROM ACTIVITY 1)
  ACCORDING TO THE FOLLOWING CLASSIFICATIONS
• (i) Optical media
• (ii) Magnetic media
• (iii) Electrical

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ELECTRICAL STORAGE MEDIA

• FLASH MEMORY CARDS
• FLASH DRIVE

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FLASH TECHNOLOGY

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

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FLASH MEMORY- Cards

• Based on EEPROM technology
• Flash memory is non-volatile
• Portable
• High Data Capacity- 512MB to 2GB
• High data transfer speed/direct access
• Flash memory cards are used in digital cameras,
  cell phones and video games

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FLASH DRIVE

• A Flash memory storage device
• Fast/direct access
• Large storage capacity
• Portable

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STORAGE MEDIAS USE
STORAGE MEDIA DESCRIPTION (USE TYPE OF DATA IT STORES)
FLOPPY DISK STORES TEXTUAL DATA
HARD DISK BACK-UP DATATEXT, 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
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COMPLETE THE TABLE
STORAGE CAPACITY PORTABILITY STORAGE METHOD METHOD OF ACCESS
Magnetic Tape
Floppy disk
Hard disk
Compact Disc
DVD
Flash Drives

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STORAGE MEDIUM CAPACITY PORTABILITY STORAGE METHOD METHOD OF ACCESS
Magnetic Tape 2GB-1.6TB Portable MAGNETIC SERIAL
Floppy disk 1.44 MB Portable MAGNETIC DIRECT
Hard disk 40 GB 1TB Usually fixed but removable MAGNETIC DIRECT
Compact Disc 650 MB- 800MB Portable OPTICAL DIRECT
DVD 4.7 GB-17GB Portable OPTICAL DIRECT
Flash Drives 128 MB 16GB Portable ELECTRICAL FLASH MEMORY (EEPROM) DIRECT
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• GAMES
• http//www.teacherxpress.com/f.php?gid35id20
• HANGMAN
• SPOT THE TEACHER
• BREAKOUT
• DRAG AND DROP (RAM, ROM,BITS AND BYTES, FLOPPIES,
  HARD DISK, STORAGE DEVICES)
• FLASH CARDS
• TRUE/FALSE