CHAPTER 8 : DIGITAL STORAGE
Storage
- A
storage medium which a computer keeps data,
information, programs, and applications.
- Cloud
storage is another storage option, actual online storage media
used is transparent to the user.
-Capacity is the number of bytes a storage medium
can hold
- Items on a storage medium remain intact
even when you turn off a computer or mobile device
- Access
time
measures:
Time it takes a storage
device to locate an item on a storage medium.
The time required to deliver an item from
memory to the processor.
Hard Disks
-A hard
disk
contains
one or more inflexible, circular platters that use magnetic particles to store
data, instructions, and information.
- A head crash occurs
when a read/write head touches the surface of a platter
- An external
hard disk
is a storage device that connects with a cable to a USB port
or other port on a computer or mobile device
Flash Memory Storage
- Flash memory chips are a type of solid
state media and contain no moving parts
- An SSD (solid state drive)
vs HDD:
- A memory
card
is a
removable flash memory device that you
insert and remove from a slot in a
computer, mobile device, or
card reader/writer.
- USB
flash drives plug into a USB port on a computer or
mobile
device.
Cloud Storage
- Cloud
storage is an
Internet service that provides storage to computer or mobile device users.
Optical Discs
-An optical
disc
consists of a flat, round, portable disc made of metal, plastic, and lacquer
that is written and read by a laser
- Optical discs commonly store items in a
single track that spirals from the center of the disc to the edge of the disc
- Track is divided into evenly sized
sectors
- A
CD-ROM
can be read from but not writable or erasable.
- A
CD-R
is an optical disc on which users can write once, but not erase
- A
CD-RW
is an erasable multi session disc
Other Types of
Storage
- A magnetic
stripe card
contains
a magnetic stripe that stores information
- A smart card stores data on an integrated circuit
embedded in the card
- Radio Frequency Identification (RFID)
•The RFID tag consists of an antenna and a memory chip that contains the information to be transmitted via radio waves
•An RFID reader reads the radio signal and transfers the information to a computer or computing device
- Microfilm
and microfiche store microscopic images of documents on
a roll or sheet film.
CHAPTER 9 : OPERATING SYSTEM
•An operating
system
(OS) is
a set of programs containing instructions that work together to coordinate all
the activities among computer and mobile device hardware
Operating System
Functions
1) Starting Computers and Mobile Devices
–If a computer or mobile device is off,
you press a power button to turn it on
2) User
interface (UI)
controls
how you enter data and instructions and how information is displayed on the
screen
3) The operating system determines the order
in which tasks are processed
J
4) Provide a means to establish Internet
connections
5) Provide users with a variety of tools
related to managing a computer, its devices, or its programs.
6) Automatic
update
automatically
provides new features or corrections to the program
7) Enables user to sign in to, or access resources on, a network or computer on user account.
Types of Operating
Systems
Desktop Operating
Systems
- A desktop
operating system is a complete operating system that works
on desktops, laptops, and some tablets such as windows, Mac OS, linux, UNIX.
- Windows 8 offers these features:
–Start screen interface with tiles
–Includes the desktop interface
–Support for input via touch, mouse, and
keyboard
–Email app, calendar app, and browser
included
–Enhanced security through an antivirus
program, firewall, and automatic updates
–Windows Store offers additional
applications for purchase
- The Macintosh operating system has
earned a reputation for its ease of use, latest
version is OS X.
Mobile Operating
Systems
=The
operating system on mobile devices and many consumer electronics
-Android
•an
open source, Linux-based mobile operating system designed by Google for
smartphones and tablets
- iOS
•developed by Apple, is a proprietary mobile operating system specifically made
for Apple’s mobile devices
- windows Phone
•developed by Microsoft, is a proprietary mobile operating system that runs on
some smartphones
