This document provides an overview of different storage types and devices in computer systems, including hard drives, floppy disks, and optical storage like CD/DVD. It categorizes storage by their operations, access methods, technologies, and hierarchies, explaining concepts such as online, near-online, and offline storage. Additionally, it discusses the performance metrics of storage devices, including capacity and access times.

3. Hard Drive – storage



RAM – memory
Storage, also known as mass media or auxiliary
storage, refers to the various media on which a computer
system can store data.
Storage devices hold programs and data in units called
files.
Memory is a temporary workplace where the computer
transfers the contents of a file while it is being used.

4. Registers
2ns
Cache (I, II, III)
SRAM
Volatile
DRAM
SDRAM
Primary
RAM
(Semiconductor – chip).
Main Memory
Memory Types &
Storage Devices
EDRAM
EDO
FLASH RAM
PROM
Non-volatile
ROM
EPROM
EEPROM
Magnetic memory
Secondary
(Devices)
Tape
HD, Zip Disk
FDD
Optical
Memory
CD-ROM, CD-R, CD-RW
DVD-ROM, DVD-R 5ms
DVD- RW

5. 
Storage devices:
Retain
Are
cheaper than memory
Play
Are
data when the computer is turned off
an important role during startup
needed for output

17. 
Storage devices are categorized by:
The
type of operations they perform
The
method they use to access the information
The
technology they use
Their location
in the storage hierarchy
Their capacity
and speed

18. Tape Drive –
sequential storage


Floppy Disk Drive –
random-access storage
Hard Disk –
random-access storage
Sequential – Storage devices that read and write
data in a serial (one after the other) fashion
Random-Access – Storage devices that read and
write data without going through a sequence of
locations

19. Magnetic Storage


Optical Storage –
CD/DVD drive
Magnetic – Storage devices use disks or tapes
that are coated with magnetically sensitive
material
Optical – Storage devices that use laser beams
to read patterns etched into plastic disks

20. 
The three levels of storage hierarchy are:



Online storage – Also called primary storage, it is
made up of the storage devices that are actively
available to the computer system. User action is not
required.
Near-online storage – Also called secondary
storage, it is not readily available to the computer
system. The user performs an action, such as
inserting a disk, to make it available.
Offline storage – Also called tertiary storage or
archival storage, it is not readily available to the
computer system. Devices such as tape backup units
store data for archival purposes.
Slide 22

21. Floppy Disk
Capacity – 720 KB to
1.44 MB
Access Time – 100ms

Hard Drive
Capacity – Up to 80 GB
Access Time – 6 to 12ms
CD ROM / DVD
Capacity – CD-ROM 650
MB; DVD 17 GB
Access Time – 80 to 800ms
A storage device’s performance is measured by:
Capacity – The number of bytes of data that a device can
hold
 Access Time – The amount of time, in milliseconds (ms), it
takes the device to begin reading data


22. Platter
Read/Write
head

Hard disks are high-speed, high-capacity storage devices.

They contain metal disks called platters.


They contain two or more stacked platters with read/write
heads for each side.
Hard disks can be divided into partitions to enable
computers to work with more than one operating system.

24. Floppy Drive




Zip Drive
A disk or diskette is a portable storage
medium.
High-density floppy disks that are commonly
used today store 1.44 MB of data.
Disks work with a disk drive.
Zip disks store up to 750 MB of data and are
not downwardly compatible with floppy
disks.
Floppy Disk

25. 



CD-ROM stands for Compact
Disc-Read Only Memory.
CD-ROM drives can not write
data to discs.
They are capable of storing 650
MB of data.
They are used for storing
operating systems, large
application programs, and
multimedia programs.

27. CD-R



Discs can be read and
written to
Discs can only be
written to “once”
CD-R drives are
capable of reading and
writing data
CD-RW




Discs can be read and
written to
Discs are erasable
Discs can be written to
many times
CD-RW drives are
capable of
reading, writing, and
erasing data

28. 




DVD stands for Digital Video Disc.
DVD technology is similar to CDROM technology.
DVDs are capable of storing up to
17GB of data.
The data transfer rate of DVD
drives is comparable to that of hard
disk drives.
DVD-R and DVD-RW drives have
the ability to read/write data.

29. 


Solid state storage devices use nonvolatile
memory chips to retain data.
They do not have moving parts.
They are small, lightweight, reliable, and
portable.

30. Smart
Card
Flash
Memory
PC
Card
Memory
Stick
Compact
Flash
Memory
Micro
Drive