IT fundamentals

• Data storage systems

• Peripherals

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 Permanent Data storage
systems:
• serial data storage
- on tape, (DAT),
features (slow(?), cheap, - archive purpose)
• random access (disk)
• What does it mean?
The disk is turning, while the read and write head is moving
over the disk surface

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 The four most important
characteristics of storage devices:

– Speed and access time

– Cost / Removable versus non-removable
– Capacity
– Type of access

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 Hard Disk

Nearly every desktop

computer, laptop and
server in use today
contains one or more
hard-disk drives. Every
mainframe and Hard disks store
supercomputer is digital
normally connected to information in a
hundreds of them. relatively
permanent form.
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Hard Disk Drives and Direct
Access

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 Capacity and Performance
• A typical desktop machine will have a hard
disk with a capacity of between 1 and 2
terabyte. Data is stored onto the disk in the
form of files. A file is simply a named
collection of bytes.
• No matter what it contains, however, a file is
simply a string of bytes. When a program
running on the computer requests a file, the
hard disk retrieves its bytes and sends them to
the CPU one at a time. 6
 Storing the Data
Data is stored on the surface of a platter in sectors
and tracks. Tracks are concentric circles, and sectors
are pie-shaped wedges on a track, like this:

A typical track is shown in yellow; a typical sector

is shown in blue. A sector contains a fixed number
of bytes -- for example, 256 or 512., sectors are
often grouped together into clusters. 7
 Data storage system
• How do hard drives work? - Kanawat Senanan
(5:11)
• https://www.youtube.com/watch?v=wteUW2s
L7bc

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 Other storage ideas:
• SSD: is a data storage device that uses solid-
state memory to store persistent data. An
SSD emulates a hard disk drive interface, thus
easily replacing it in most applications.(wiki)
• http://en.wikipedia.org/wiki/Solid_state_memo
ry
• HDD vs SSD - What is the difference? (11:07)

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 Peripherials
• General definition (5:08)
• https://www.youtube.com/watch?v=M0F4cc2d
kV8
• Component
• https://www.youtube.com/watch?v=yRmPTbG
BqVI

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 Peripherals
• Keyboard, Monitor, printers, speakers, etc.

• Notes:
• Peripherals differ from computer to computer.

• Easy addition/removal/replacement of I/O

devices should be allowed.

• Design of computer should be flexible to allow

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this.
 Input Devices
• Human input devices
– Allow person to send data to the computer
– Keyboard
– Mouse (and other pointing devices)
• Machine-readable input devices
– Send data directly to computer without human
involvement
– No human involvement means no human error
– Usually faster than human input
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 Input devices: Keyboard
• Keyboards are designed for the input of text
and characters and also to control the operation
of a computer.
• To produce some symbols requires pressing
and holding several keys simultaneously or in
sequence.
• A keyboard is also used to type commands in a
computer. One famous example on the PC is
the Ctrl+Alt+Del combination. With current
versions of Windows, this brings up a menu- 13
 Inside the Keyboard
• A keyboard is a lot like a miniature computer. It has
its own processor and circuitry that carries
information to and from that processor. (11)

• A large part of this circuitry makes up the key matrix.

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 Input devices: Mouse
• A mouse is a small device that a computer user
pushes across a desk surface in order to point
to a place on a display screen and to select one
or more actions to take from that position.

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Machine-readable Input Devices
• Bar code scanners
– Uses light to read series of coded stripes
• Optical Character Recognition (OCR)
– Software that works with scanner
– Translates scanned digital image to character that
user can recognize and manipulate
• Magnetic Ink Character Recognition (MICR)
– Character recognition technology used by banks to
allow rapid routing of checks between banks
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17
 Display Technology
• The display is the most-used output device on
a computer. The display provides instant
feedback by showing you text and graphic
images as you work or play.
• Most desktop displays use liquid crystal
display (LCD) or cathode ray tube (CRT) or
(LED) Light-Emmiteng Diodes technology,
while nearly all portable computing devices
such as laptops incorporate LCD technology
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 Standards and Resolution
• Resolution refers to the number of individual
dots of color, known as pixels, contained on a
display. Resolution is expressed by identifying
the number of pixels on the horizontal axis
(rows) and the number on the vertical axis
(columns), such as 1024x768. Resolution is
affected by a number of factors, including the
size of the screen.

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 Measures of monitor
• The measure of screen 14”,…17”…25
- The measure of pixel
- The number of rows and columns
from 640x480 to 1920x1080 (HD) or more
- The frequency of refresh the screen
- The numbers of colours, max. 16,7 million
• History (23.video 12+13)
• https://thecrashcourse.com/courses/computerscience
• GUI: (Graphical User Interfaces)
• https://www.youtube.com/watch?v=XIGSJshYb90
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 Monitors
• Hi-resolution monitors come in two types:

• Cathode ray tube (CRT) - Streams of electrons make

phosphors glow on a large vacuum tube. This technology is
now obsolete.
• Liquid crystal display (LCD) - A flat panel display that uses
crystals to let varying amounts of different coloured light to
pass through it. Developed primarily for portable computers
• Concept vid from 2010:
• http://www.youtube.com/watch?v=g7_mOdi3O5E

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 Printers
• Printer prints
– character symbols
– Graphics
• Output quality is measured in dpi dots per inch
• Printers vary from 60 to 1500 dpi
• 600 dpi seems common

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 Types of printers: impact
• Forms characters or images by mechanic
strikes of a print hammer or wheel.
• Most common form is STILL the dot matrix
printer
– Head with small pins (9, 24)
– Strike ribbon against paper
– Do 72 to 144 dpi, 30 to 400 chars
– Noisy
– Image may smear
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 Types of printers: non-impact
• Form characters and images without physical
contact
• Less moving parts, less noise
• Two forms
– Laser printer
– Inkjet printer

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 Ports & Cables
• A port is a connecting socket or jack on the outside of
the system unit into which are plugged different kinds
of cables.
– Serial port - sends bits one at a time, one after another
– Parallel port
– SCSI port
– USB port
– FireWire port
– Infrared port
– HDMI port

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 Multimedia I/O Devices
• Music, images, and video
– Convert content to digital form
– Digital cameras; digital camera phones
– Digital Video DVD recorders
• Voice recognition
• Text-to-speech
• Brain wave input

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Thank you for your attention!

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