Grade 8 Information Technology: Secondary Memory

• Week 2 is about Information Technology
• The class is in Grade 8
• The date is January 13-17, 2025
• The lesson is 2 periods and 70 minutes long
• Topic is secondary memory
• Sub-topic is magnetic media, optical media, and miniature media
• Objectives are to define secondary storage and categorize devices as magnetic, optical, or miniature media
• Primary Memory is also referred to as main memory or immediate access storage
• Main memory contains the data that is currently being executed by the computer
• RAM is Random Access Memory
• ROM is Read Only Memory

Secondary Storage

• This is also called permanent storage
• Retains programs and data for future use
• Common secondary storage media are hard disks, CD-ROMs and USB drives
• A storage medium is a physical device or material where data is stored for future use
• It permanently or temporarily retains digital information such as documents, videos, images, and applications

Types of Storage Medium

• Storage mediums are categorized based on how they store data and their physical or digital nature
• Magnetic storage medium has data that is stored magnetically on spinning disks or tapes
• Examples of magnetic storage mediums are hard disk drives (HDDs), floppy disks, and magnetic tapes
• Magnetic storage medium is commonly used for large capacity storage and backups
• Data is stored on magnetic media by magnetizing tiny regions on the surface, known as magnetic domains, which represent binary values (0s and 1s)
• Data is organized in tracks and sectors allowing efficient storage and retrieval
• Magnetic media such as hard disk drives (HDDs) and tapes are durable and rewritable, making them suitable for large capacity storage

Floppy Diskettes

• Diskettes storage capacity is limited to 1.44 MB
• Most commonly they came in a size of 3.5 inches
• Dust, moisture, and magnetic interference can damage data stored on these floppies

Hard Disk

• The most common medium used to store data in a computer system
• Found inside of the system unit as central storage for programs and data
• Hard disk capacity ranges from Gigabytes to Terabytes (120 GB - 2 TB)
• The time to access data is as low as 8 ms as compared with 84 ms for a floppy disk
• External hard drives make the data stored on the hard drive portable

Magnetic Tape

• Also known as data tapes, used for data archival purposes
• Used for off-site storage so data could be retrieved from the tape in the case of a disaster
• Data tapes are popular because they store a large amount of data at a relatively low cost and are portable because of their light weight and size
• It takes longer to find an individual item of data from a magnetic tape due to sequential access

True or False - Memory Check

• Secondary storage is also known as permanent storage = True
• Hard disk drives (HDDs) are examples of optical storage media = False
• Magnetic tapes use direct access to retrieve data = False
• Magnetic media are durable and rewritable, making them suitable for large-capacity storage = True
• Diskettes have a storage capacity of 2 TB = False

Fill in the Blanks - Memory Check

• Data on magnetic media is stored by magnetizing tiny regions called magnetic domains
• A floppy diskettes storage capacity is 1.44 MB
• Magnetic tapes are commonly used for data archival purposes.
• Hard disk capacity ranges from Gigabytes (GB) to Terabytes (TB).
• External hard drives are used to make data stored on the hard drive portable.

Optical Storage Medium

• Data is written and read using a laser on a reflective surface
• Examples are CDs, DVDs, and Blu-ray Discs
• Suitable for media distribution and archiving
• Data is stored here in the form of tiny pits and lands, which represent binary data
• Common examples include compact discs (CDs), digital versatile discs (DVDs), and Blu-ray discs
• These are widely used for storing multimedia files, software, and backup data
• Optical storage is durable, portable, and cost-effective
• Typically has slower read/write speeds and lower storage capacity compared to solid-state drives (SSDs) or hard disk drives (HDDs)
• Used for distribution of content and archiving data

Optical Storage Medium – CD-ROM

• CD-ROM and DVD-ROM drives come with the ability to read and/or write data to the disk
• Drives that are labelled as ROM can only read data and those that labeled RW can read and write data
• A CD-ROM has a capacity of 700 MB while a DVD-ROM has a capacity of 4.7 GB
• The time to retrieve data is slower than that of a hard drive

Optical Storage Medium – Blu-ray

• They are very popular as they are small, lightweight and very portable with a large capacity
• They use blue-violet laser beam instead of the red laser beam
• Offers more than five times the storage capacity of traditional DVDs
• Can hold up to 25GB on a single-layer disk

True or False Questions - Memory Check

• Optical storage media use laser technology to read and write data = True
• CDs, DVDs, and Blu-ray Discs are examples of optical storage media = True
• Optical storage media have higher read/write speeds compared to SSDs = False
• Drives labeled as RW can both read and write data to optical discs = True
• Blu-ray optical disks use a red laser beam for reading and writing data = False

Fill in the Blanks - Memory Check

• Data on optical storage media is stored in the form of tiny pits and lands.
• Examples of optical storage media include CDs, DVDs, and Blu-ray Discs.
• A CD-ROM has a storage capacity of 700 MB.
• A DVD-ROM can hold up to 4.7 GB of data.
• Blu-ray optical disks use a blue-violet laser beam instead of the traditional red laser beam.

Miniature Storage Mediums

• Data is stored on flash memory chips, which have no moving parts
• USB Flash Drives, Memory Cards.
• Fast and reliable storage for modern devices like smartphones, laptops, and gaming consoles

Summary

• Magnetic storage uses magnetized surfaces to store data and optical storage uses laser beams
• Magnetic: HDDs (120 GB - 2 TB+), Floppy Disks (1.44 MB), Magnetic Tapes for large archival storage
• Optical: CD-ROM (700 MB), DVD-ROM (4.7 GB), Blu-ray (25 GB+).
• External HDDs and tapes are portable for backups. Optical storage is lightweight, portable, and ideal for distributing data.

Speed and Access

• Magnetic storage offers faster direct access compared to optical storage
• Optical media retrieval is slower than hard drives but sufficient for general use

Durability and Application

• Magnetic storage is durable and rewritable, used for backups and high-capacity needs
• Optical storage is preferred for portability, media distribution, and archival purposes

This lesson for Grade 8 IT defines secondary storage and its role in retaining programs and data. It categorizes storage devices into magnetic, optical, and miniature media, emphasizing their importance for long-term data preservation.