Download - Intro to computer fundamentals
Introduction to Computers
IT Preparatory CourseDiploma in NursingUnity College International
2
Are you a beginner
With computers? This course will helps you learn about
computers in an easy, friendly way
3
Compare a computer
To a workshop such as Woodshop Kitchen
4
Typical workshop features
Materials Tools Working Area Storage Measurements (may be English or
metric)
5
Woodshop
Materials: Wood Tools: Hammer, saw, drill… Work area: Worktable Storage: Cabinet Measurements Yards, feet, inches,
meters, centimeters, millimeters
6
Kitchen
Materials: Food Tools: Stove, mixer, spoon… Work Area: Counter, cutting board,
bowl… Storage: Refrigerator, cabinet… Measurements: Cups, tablespoons,
teaspoons, ounces pints, grams, liters
7
Computers
How does this apply to computers? You will find materials, tools, work
area, storage, and measurements
8
Computer Materials
Information Words Numbers Pictures
9
Computer Tools
Two kinds: Hardware
Physical parts to computer Software
Instructions This slide show for example
10
Computer Working Area
The work area of a computer is called a window.
The next slide shows a typical window.
You will use some windows in the last part of this class and in future classes.
11
Typical Window
12
Computer Storage
Two main types: Memory Data Storage
13
Memory Often called RAM (Random Access
Memory) Information while you work on it
(like food while you eat it) Usually temporary (easily lost)
14
Data Storage Information stored away for use later on
(like food in the refrigerator) Usually long-term (safer) May be stored on disks, CDs. DVDs, or
flash drives
15
Measuring Information
Bytes One character takes up about one Byte. An email takes up a few (thousand
bytes) Kilobytes (thousands of bytes) A picture may take up Megabytes
(millions of bytes) All the information on a computer may
run into Gigabytes (billions of bytes)
16
Storage Examples
Email, about a thousand characters Picture of granddaughter, about half a megabyte
17
Hardware
Central Processing Unit (cpu) Brains of a computer
18
Disks Floppy Disk
Main disk used for library users
Holds 1.44 Megabytes 1,440,000
Bytes Feels hard
Floppy part inside cover
Almost obsolete
19
Hard Disk Main disk for
most computers
Holds Windows, software, and most data
Usually don’t see it because it’s inside computer.
20
CD-ROM Uses optical
(laser) technology instead of magnetic
Holds large amount of data
Same technology as a music disk.
Not available on library computers
21
Disks Disk geometry may vary
Different disks may have different number of sectors per track
Hide these details using a virtual geometry presented to the OS
Virtual geometry defined by x cylinders, y heads, and z sectors per track
Disk controller maps virtual to real geometry
Alternative: logical block addressing disk sectors numbered consecutively starting
at 0 No limits on number of sectors (depending)
Sectors and Tracks
23
Overview of Computer Hardware
Magnetic Disk Used the most for permanent
storage in computers In principal, stores data pretty
much the same way as tapes Magnetic coating covers the disk Takes magnetic charge to
represent data Divided into tracks and sectors
Tracks are concentric circles on the disk
Sectors divide the disk into pie-shaped areas
Data fills all track within one sector
All tracks can store the same number of bits!!! more compact towards
the center (higher density)
24
25
R/W Head
R/W head can move to any position (sector, track) on the disk random access
26
Overview of Computer Hardware
Comes in two forms: Portable
Floppy disks Because they are flexible (easily bent) 3.5’’ 1.44 MB
27
Calculations
Information Given : A magnetic disk is labeled M Able to write on 1 side. 40 sectors 60 tracks 1 cluster = 2 sector track I sector-track=512 byte
28
Calculate
The number of sector-track on one side? 40 x 60 = 2400 sector-track The number of sector-track on both sides? 2400 sector-track because the other side =
0 How much can be stored on one side? 2400 x 512 byte = 1228800 bytes How much can be stored on both sides? 1228800 bytes
29
Calculate
How many cluster on one side? 2400/2= 1200 clusters How many cluster on entire disk? 1200 clusters What is the total track in the entire
disk? 60 tracks
30
Exercise in class
Information Given : A magnetic disk is labeled J Able to write on 2 sides. 80 sectors 90 tracks 1 cluster = 2 sector track I sector-track=512 byte
31
Calculate :
The number of sector-track on one side? The number of sector-track on both sides? How much can be stored on one side? How much can be stored on both sides? How many cluster on one side? How many cluster on entire disk? What is the total track in the entire disk?
32
Overview of Computer Hardware
Fixed Hard disks Single (PCs) or multiple (~
10 to 12) Multiple GBs per disk Diskettes have 135 tracks
per inch and 18 tracks HDs have 1000s of tracks
per inch and 64 tracks R/W does not touch the
surface but floats right above it Rotate 100 times faster than diskettes
They are sealed so that no dirt comes between R/W head and disk (corrupts data)
Disk Pack
33
Overview of Computer Hardware
Compact Disks (CDs) Optical disk Data stored like magnetic disks (series of dots on tracks)
Now we BURN the dots (rather than magnetic charges) as pits on the surface
A laser detects those pits as 0s Data spans a track of the disk (not sectors) Pits gives the advantage of more density of storage
600 MB to 10 GB Most CDs are Read-only (because of the burning) Some optical drives do allow for re-burning of surface
after smoothing out the pits
34
Cutaway View of a Multi-Platter Hard Disk Drive
35
Simplified View of Disk Track and Sector Organization
An integral number of sectors are recorded around a track
A sector is the unit of data transfer to or from the disk
36
Simplified View of Individual Bits Encoded on a Disk Track
Inside tracks are shorter & thus have higher densities or fewer words
All sectors contain the same number of bytes Inner portions of a
platter may have fewer sectors per track
Small areas of the disk are magnetized in different directions
• Change in magnetization direction is what is detected on read
37
Photo of Disk Head, Arm, Actuator
ActuatorArm
Head
Platters
{Spindle
38
Disk Device Terminology
Several platters, with information recorded magnetically on both surfaces (usually)
Actuator moves head (end of arm,1/surface) over track (“seek”), select surface, wait for sector rotate under head, then read or write “Cylinder”: all tracks under heads
Bits recorded in tracks, which in turn divided into sectors (e.g., 512 Bytes)
Platter
OuterTrack
InnerTrackSector
Actuator
HeadArm
39
DVD Replacing CD-ROM Holds much larger amount of
information (such as movie) Also does not work on library
computers
40
Zip Disk
Similar to floppy Thicker form Holds more information Available on some library computers Also becoming obsolete
41
Flash Drive
Most recent widely used storage system
Very portable, often worn like jewelry 128-512 Megabytes most common
sizes
42
Classes for beginners
No particular order in this group Free! Can take more than once
Basic Skills Internet Level 1 MS Word Level 1
43
Time to practice a bit
Advance twice to end slide show If time allows you will practice a bit to
see what it is like to take our classes
44
The End
Zainudin Johari
B Sc (Hons ) Computer Science, UPM M Sc Information Systems, UPM