Storing Data: Electronic Filing Cabinets

What You Will Learn

Difference between memory and storage

How storage media are categorized

Measuring a storage device’s performance

How data is stored on hard and floppy disks

Characteristics of hard drives

Uses of removable disks

Various optical storage media

New storage media

What is the difference between memory and storage?

Storage devices hold programs and data in units called files

Files are stored in directories or folders

Memory is a temporary workplace where the computer transfers the contents of a file while it is being used

Hard Drive RAM memory

Why is storage necessary?

Storage retains data when the computer is turned off

Storage is cheaper than memory

Storage plays an important role during startup

Storage plays an input role when starting applications

Storage is needed for output

Storage devices can hold a large amount of data

What is a storage device?

Hardware that is capable of retaining data when electricity is turned off

Able to read (retrieve) data from a storage medium (disk/tape)

Able to write (record) data to a storage medium

What are the types of storage technologies?

Sequential- Hardware that reads and writes data in a serial (one after the other) fashion

Random Access- Hardware that reads and writes data without going through a sequence of locations

Magnetic- Hardware that uses disks or tapes that are coated with magnetic material

Optical- Hardware that uses laser beams to read data from plastic disks

Solid State- Devices that use nonvolatile memory chips to read and write data

Sequential – Magnetic Storage

Random Access – Magnetic Storage

Tape Backup Unit

Floppy Drive Hard Drive Jaz Drive Zip Drive

Sequential – Optical Storage

CD ROM / DVD Drive

Magnetic – Optical Storage

Magneto-Optic (MO) Drive

Solid State Storage

Compact Flash Memory

Flash Memory

Smart Card

Micro Drive

Memory

Stick

PC Card

How is a storage device’s performance measured?

Capacity- The number of bytes of data that a device can hold

Access Time- The amount of time it takes for the device to begin reading data; measured in milliseconds (ms)

Floppy Disk

Hard Drive CD ROM / DVD

Capacity- 720KB to 1.44 MB

Access Time- 100ms

Capacity- Up to 80 GB

Access Time- 6 to 12ms

Capacity- CD Rom 650MB; DVD 17GB

Access Time- 80 to 800ms

What are hard disk drives?

A high speed, high capacity storage device

Consists of metal disks called platters

Contains two or more stacked platters with read/write heads for each side

Works similarly to floppy disk drives

What affects a hard disk’s performance?

Seek time or positioning performance- How quickly the read/write head positions itself and begins transferring information. Measured in milliseconds (ms)

Spindle speed or transfer performance- How quickly the drive transfers data. Measured in rotations per minute (RPM)

What are hard disk interfaces?

Enables the hard disk to communicate with the CPU by way of the hard disk controller

Types of interfaces

Integrated Drive Electronics (IDE)- also called ATA or IDE/ATA

Serial ATA interfaces, also known as SATA150

Small Computer System Interface (SCSI)

FireWire/IEEE 1394

What is a removable hard disk?

Platters are enclosed in a cartridge which can be inserted or removed from a drive

Used for data archiving and data backup

Usually connected via USB

Jaz Drive

What is a tape backup unit?

A device used to store large amounts of data that are not used frequently

Uses cassette type reel to reel plastic tape

Tape Backup Unit

What is a CD-ROM?

Stands for compact disk-read only memory

CD-ROM drives can not write data to disks

Capable of storing 700MB of data

Used for storing operating systems, large application programs, and multimedia programs

How does a CD-ROM drive work?

Laser beams read microscopic patterns of data on the disk’s surface

Disks contain indentations (pits) and flat reflective areas (land)

The computer interprets the pits as 0’s and the lands as 1’s

What is CD-R and CD-RW?

CD-R

Disks that can be read and written to

Disks can only be written to “once”

Drives that are capable of reading and writing data

CD-RW Disks that can be read and written to

Disks are erasable

Disks can be written to many times

Drives that are capable of reading, writing and erasing data

What is DVD?

Stands for digital video disk

Uses similar technology as CD-ROM

Capable of storing up to 17GB of data

Data transfer rate comparable to hard disk drive

Compatible with CD-ROM disks

DVD-RAM- Ability to read/write data

What is solid state storage?

Nonvolatile memory chips used to retain data

Solid state storage devices do not have moving parts

Solid state storage devices are small, lightweight, reliable, and portable

Types of solid state storage devices

PC or PCMCIA card- Credit card sized device used mainly with notebook computers; Various functions (modem, adapter, memory and storage)

Types of solid state storage devices

Flash memory card- Wafer thin card used with cellular phones, MP3 players, and digital cameras

Types of flash memory cards- SmartMedia card, CompactFlash card, and Sony’s Memory Stick

CompactFlash Memory StickSmartMedia

Types of solid state storage devices

Smart card- Credit card sized device combining flash memory with a microprocessor; Used as a credit card; Has more functionality, convenience, and safety than credit cards

THE

END