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Objectives
LO1/4 : Understand the44 function of computer systems
Computer systems: microcomputers eg personal computers; mobile computers;
minicomputers eg mid-range servers, workstations; mainframes eg large scale network
systems; supercomputers eg high performance systems; models; multiprocessing
Environments: home, business, computer gaming, networking, real-time, communication
Function: main components (Arithmetic Logic Unit (ALU), control unit, memory and
input/output devices), connection eg busses; Central Processing Unit (CPU) (control unit,
arithmetic logic unit, registers, input/output); memory (Random Access Memory (RAM),
Read Only Memory (ROM), registers, programmable, cache), auxiliary storage;
computer architecture
Hardware: central processing unit; motherboard, power supply unit, cooling units,
backing storage eg hard disc drive; controllers, ports, main memory, memory types,
battery, specialised cards eg Peripheral Component Interconnect (PCI), Accelerated
Graphics Port (AGP), network, graphics, modem, sound, optical drives; performance
factors
Software: systems software eg operating systems, utility programs, library programs,
translator programs; applications software eg special purpose software, be-spoke software;
performance factors
Peripherals: printers, plotters, cameras, scanners; keyboard and mouse; monitors, display
adapters; multimedia devices; storage media; networking; portable drives; plug and play
components; performance factors
Storage
Storage medium
secondary storage
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Storage
Capacity
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Storage
storage device
Storage
access time
Time it takes storage device to locate item on storage medium
Time required to deliver item from memory to processor
faster Stores
transfer Primary Storage
rates
Memory (most RAM) Items waiting to be interpreted
and executed by the processor
Secondary Storage
Hard Disk Operating system, application
software, user data and information
Flash Memory Cards Digital pictures or files
and USB Flash Drives to be transported
CDs and DVDs Software, backups, movies, music
Tape Backups
slower
transfer Floppy Disk Small files to be transported
rates
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Hard Disks
hard disk
Hard Disks
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Hard Disks
Magnetic Disks
Track Sector stores
is narrow
up to
recording band
that forms full 512 bytes
circle on disk of data
Formatting prepares disk for use and marks bad sectors as unusable
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Hard Disks
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Hard Disk
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Hard Disk
floppy disk
shutter
Portable, inexpensive storage
medium (also called diskette)
shell
liner
magnetic
coating
Thin, circular, flexible film enclosed
in 3.5 wide plastic shell
metal hub
flexible thin film
Hard Disk
floppy disk drive
Device that reads from and
writes to floppy disk
One floppy drive, named drive A Floppy disk drive built into
a desktop computer
Also called secondary storage
External floppy disk drive attaches to
a computer with a cable
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Hard Disk
write-protect notch
Small opening with a cover that you slide
Protects floppy disk from being erased accidentally
write-protected
notch open
means you
cannot write
on the disk
not write-protected
notch closed hole on this
means you side means
can write on disk is high
the disk density
Hard Disk
Zip disk
Magnetic medium that stores 100 MB
to 750 MB of data
Used to back up and to transfer files
Backup is duplicate of file, program, or
disk in case original is lost
Zip disks require a Zip drive high
c
capacity drive that reads from and
c c
writes on a Zip disk
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Hard Disk
hard disk installed
hard disk in system unit
High-capacity storage
Consists of several
inflexible, circular
platters that store items
electronically
Components enclosed in
airtight, sealed case for
protection
Hard Disk
Sample Hard Disk Characteristics
Advertised capacity 120 GB
Platters 3
Read/write heads 6
Cylinders 16,383
Bytes per second 512
Sectors per track 63
Sectors per drive 234,441,648 actual
disk
Revolutions per minute 7,200 capacity
Transfer rate 133 MB per second
Access time 8.9 ms
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Hard Disk
Step 3.
When software requests a
disk access, read/write
heads determine current
Step 2. or new location of data.
Small motor spins
platters while
computer is running.
Step 4.
Head actuator positions
read/write head arms over
Step 1. correct location on platters
Circuit board controls to read or write data.
movement of head actuator
and a small motor.
Hard Disk
platter
track
Vertical section of sector
track through all
platters
Single movement
of read/write
head arms
accesses all
read/write
platters head
in cylinder
platter
sides
cylinder
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Hard Disk
hair
read/write head
dust
clearance smoke
platter
Hard Disk
Provide users with greater storage capacities than flash memory
Some have a form factor of less than 1 inch
Storage capacities range from 2 GB to 100 GB
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Hard Disk - External
external hard disks removable hard
disks
Removable hard diskhard disk
that you insert and remove
from hard disk drive
External hard diskfreestanding
hard disk that connects to system unit
Hard Disk - External
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Hard Disk
RAID
network attached storage
Magnetic Disks
Chip and circuits that SATA (Serial Advanced
control transfer of Technology Attachment) controller
items from disk uses serial signals to transfer data,
instructions, and information
SCSI
EIDE (Enhanced Integrated Drive (Small Computer System Interface)
Electronics) controller supports four controller supports up to fifteen
hard disks, provides connections for devices including hard disks, CD
CD and DVD drives and DVD drives, tape drives, printers,
scanners, network cards
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Magnetic Disks
online storage
Service on Web that provides storage for minimal
monthly fee
Files can be accessed from any
computer with Web access
Large files can be downloaded
instantaneously
Others can be authorized to
access your data
Optical Discs
Push the button to
slide out the tray.
Flat, round, portable
metal discs made of
metal, plastic, and
lacquer
Can be read only or Insert the disc,
read/write label side up.
Most PCs include an
optical disc drive
Push the same button
to close the tray.
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Optical Discs
Do not expose
the disc to
excessive
heat or
sunlight
Do store the
disc in a jewel
box when
not in use
Do not
eat, smoke, or Do not stack discs
drink near
a disc
Do not touch
the underside
of the disc Do hold a disc
by its edges
Optical Discs
CD-ROM
Compact disc read-only memory
Cannot erase or modify contents
Typically holds 650 MB to 1 GB
Commonly used to distribute multimedia and complex software
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Optical Discs
Picture CD
Film developers Can be
Stores digital
offer modified
versions of
Picture CD using photo
roll of film
service editing software
Step 1. Step 3.
Drop off film to At home, print images
be developed. from Picture CD on
Step 2.
Mark the Picture your ink-jet photo printer.
When you pick up
CD box on the
prints and negatives, a At a store, print images to
film-processing
Picture CD contains Picture CD at kiosk.
envelope.
digital images of each
photograph.
Optical Discs
CD-Rs CD-RWs Must have
CD recorder
or CD-R drive
CD-R (compact disc-recordable)
disc you can write on once
c
Cannot erase
discs contents
CD-RW (compact disc-rewritable)
erasable disc you can write on
multiple times
ce
Must have
CD-RW software
and CD-RW drive
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Optical Discs
DVD-ROM
High capacity disc capable of
storing 4.7 GB to 17 GB
Must have DVD-ROM drive or
DVD player to read DVD-ROM
Stores databases, music,
complex software, and movies
Optical Discs
Two layers of pits are used, lower layer is semitransparent so
laser can read through
Some are double-sided
Blu-Ray discs currently have a storage capacity of up to 27 GB
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Tape
tape
Magnetically coated plastic ribbon
capable of storing large amounts
of data at low cost
Primarily used for backup
Tape
Sequential access
Reads and writes data consecutively, like
music tape
Unlike direct access used on floppy disks,
Zip disks, hard disks, CDs, and DVDs
which can locate particular item immediately
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PC Cards
PC Card
Adds capabilities to computer
Credit-card-sized device commonly
used in notebook computers
Miniature Mobile Storage Media
Storage for small mobile devices
CompactFlash Smart Media Secure Digital
Memory Stick xD Picture Card
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Miniature Mobile Storage Media
USB Flash Drive
Plugs in a USB port on a
computer or mobile device
Storage capacities up to 4 GB
May eventually make the floppy
disk obsolete
Miniature Mobile Storage Media
smart card
Stores data on microprocessor
embedded in small card
Input, process, output, and
storage capabilities
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Flash Memory Storage
Solid state drives SSDs
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Flash Memory Storage
memory card
Secure Digital
CompactFlash Secure Digital
High Capacity microSD
(CF) (SD)
(SDHC)
xD Picture Memory Stick
microSDHC Memory Stick
Card Micro (M2)
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Flash Memory Storage
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Flash Memory Storage
USB flash drives
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Microfilm and Microfiche
microfilm microfiche
Store microscopic images of
documents on roll or sheet of film
Images recorded using
computer output microfilm recorder
Microfilm 100- to Microfiche small sheet
215-foot roll of film of film, usually 4 6
Microfilm and Microfiche
Microfilm and microfiche have longest life of any storage media
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Cloud Storage
Cloud storage
Cloud Storage
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Cloud Storage
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Other Types of Storage
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Other Types of Storage
Putting It All Together
80 GB hard disk
Online storage
CD or DVD drive
Card reader/writer
USB flash drive and/or 3.5-inch
Home
floppy disk drive
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Putting It All Together
750 MB Zip drive
120 GB hard disk
Online storage
CD or DVD drive
External hard drive for backup
Small Office/
Home Office (SOHO) USB flash drive and/or 3.5-inch floppy
disk drive
Putting It All Together
80 GB hard disk
Online storage
CD or DVD drive
Card reader/writer
Portable hard disk for backup
Mobile USB flash drive, and/or 2 GB PC Card hard
disk, and/or 3.5-inch floppy disk drive
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Putting It All Together
Putting It All Together
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Summary
References
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