Transcript What’s in the box? An overview
What’s in the box? Overview of Essential Concepts
What we’ll cover for this topic:
• What is a computer?
• What are its limitations?
• Logical vs. physical structure of computers • Some important digressions • A little about speed and capacity
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What is a computer?
• How was a “computer” defined before 1940s...?
• Agricultural tools => Industrial tools => Mind tools • Intelligence Amplifier, rather than
Artificial Intelligence
– Software: stored knowledge – “I’m deeply committed to the belief that a MIND plus a machine can do MORE than either a mind or machine alone on HARD problems.”…………………………Fred Brooks • Power tool
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• A concept manipulator – But it only manipulates form,
not
meaning
.
• A
symbol
-processing machine – The universal language of computers: symbols.
–
IT DOESN’T CARE !
• A
transformation
machine – An abstract machine used to transform
data
useful
information
.
into
DATA & INSTRUCTIONS IN COMPUTER
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Transformation In the “box” INFO OUT
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• Account info • PIN • Withdrawal
ATM MACHINE
COMPUTER
Checks for availability of funds
• Here’s your money or • Get real
POS TERMINAL
Item Bar code # COMPUTER
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Looks up price in store database
Bananas $1.49/lb!
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IRS
• Gross Income • Federal Withholding
Device that:
–
Accepts input
–
Processes data
–
Stores data
–
Produces output
Is that all it does?
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COMPUTER • Refund!
or • You owe $$ and/or • Audit!
Think of some tool and tell it to a neighbor (not a computerized tool)..
What makes a computer different?
PROGRAMMABILITY !!!
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Important digression!
• Computers must be able to
REPRESENT
various kinds of information that people care about.
• Computers must be able to
TRANSFORM
information (meaningful inputs to meaningful outputs).
But… • Computer hardware usually supports only very basic
data types
and
transformations
.
– E.g.: most
hardware
supports the addition of two integer (whole number) values: 3 5
Adder
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Simple operations … … but complex tasks
LIKE COOKING!
Ingredients (flour, eggs, water, baking powder)
Hot and delicious pancakes
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Simple operations … … but complex tasks
Simple tasks
–Crack egg –Mix –Pour –Flip :
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Making Pancakes (recipe)
: 1. Crack egg 2. Pour (egg into bowl) 3. Pour (flour into bowl) 4. Pour (water into bowl) 5. Pour (baking powder into bowl) 6. Mix 7. Pour (mixture into hot frying pan) 8. Flip 9. Repeat step 8 until done What's in the box?
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FIRST BIG QUESTION
• How can hardware that can
perform
only a few really basic operations (like a simple addition) do more complex operations (transformations)?
ANSWER? They are
PROGRAMMABLE For example:
our simple hardware supports whole numbers and a simple ADD.
– So how can it multiply? What is multiplication?
– Once the multiplication operation is defined, then it, too, can be used to define yet
other
operations.
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SECOND BIG QUESTION
• How can hardware that can
represent
only whole number values be used to represent more
complex
data values (real numbers; negative numbers; characters; sounds…)?
ANSWER? New data types can be
defined
similarly.
For example:
I can speak faster than you can write.
– So what can you do to improve the speed of your note-taking? – Instead of FOR YOU…?
– Instead of as soon as possible…?
– Instead of true or false…?
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• As
long
as the
meaning
is understood, the exact representation is not important.
• The rules people define for
transforming
data depend on the
representations
that we choose for the data.
=> that’s computer science in a nutshell • Most concepts underlying computer operation are not new and are reasonably straightforward.
• Complexity lies in the
details
. We’ll look at some of them this semester.
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Some concepts (details) coming later
• Representing data/information – Will show how many common
types
of data are
represented
computers.
using the simpler data types available in • Memory/storage systems – Will discuss where information is stored in a computer and why.
• Computer architecture – Will explain in more detail how
transformations
done in a computer and how software extends the computer hardware’s basic functionality.
are
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Some concepts (details) coming later
• Why is the operating system important?
– Will explain how physical devices, such as the processor and the mouse, are coordinated.
• Programming – Will explain the concept of architecture-independent programming languages.
• Telecommunications concepts – Explain how computers communicate with each other over networks .
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The limitation of computers
• Can a computer, by itself: – Cure cancer?
– Save the whales?
– Eliminate starvation?
– Prevent crime?
• Computers only
FOLLOW
instructions provided by people. Computers cannot solve problems by themselves.
• Computers are only
TOOLS
.
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How to Solve a Problem
• To solve a problem, one must first: – –
UNDERSTAND
the problem
MODEL
the problem – DEVELOP an
IDEA
for solving the problem.
• Computers cannot do these things for us, but they sure can help us to develop ideas and understanding
faster
.
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Can and Cannot Do
• A computer – cannot cure cancer; but it can be used to
analyze
the
behavior
of cancer and its
reactions
to various therapies.
– cannot save the whales, but it can be used to
track
migration patterns, which will help us understand why they are endangered.
– cannot eliminate crime, but it can be used to detect crime and
recognize
social and economic
patterns
that lead to high crime rates.
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So what’s the power of computers?
• Allows one person to use the
expertise
another person.
of • They work MUCH
faster
than people.
• They are usually more
reliable
than people when it comes to performing
repetitive
or
tedious tasks
.
• They allow us to investigate new areas that were previously closed off to us.
– Mapping the human genome – Space travel …
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Computers as general-purpose tools
• Hardware – Electronics & mechanical parts.
• Software (hardware useless without it) –
Program
: set of instructions done one after other.
Go
down to the basement ,
Look Take
in the a loaf fridge , of rye bread,
Bring
the loaf up here,
Toast Butter
three slices , the slices .
• Instructions: imperative. Each has a
verb
&
noun
.
• Program: could be
stored
in deck of cards, on a paper tape, on a disk, or in electronic memory.
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Hardware: Basic Components
What are the basic components of a computer?
– Input devices – Output devices – Processing hardware – Storage devices
Most common examples of each?
– Keyboard and mouse – Display and printer – CPU (housed in the
system unit
) – Hard Drive, floppy disk drive, Main Memory
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COMPUTER System
Processor Inputs program data Storage data info program Outputs info
Which changes more drastically over time?
Storage
(two kinds): for data, info, programs –
Primary
(
main
)
memory
–
Auxiliary memory (
secondary
storage) COMP 4—Power Tools for the Mind
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Inputs program data COMPUTER SYSTEM (expanded) : Processor Memory data & programs
that are in use now
Outputs info Auxiliary Storage Lots of programs & data, that will be used later.
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COMPUTER SYSTEM (from Vendor) :
• • • • • • • • • • • • • Specs from Dell:
Processor
: Pentium® 4 at 2.8Ghz
Memory
: 2GB PC800 RDRAM
Keyboard
: Dell® Enhanced Performance USB Keyboard
Monitor
: 21 in (19.8 in viewable, .24AG)P1110 FD Trinitron® Monitor • •
Video Card
: Asus Geforce FX5800 128MB AGP8X TV •
Hard Drive
: 120GB Ultra ATA/100 Hard Drive •
Floppy Drive
: 3.5 in Floppy Drive
Operating System
: Microsoft® Windows® XP Professional • •
Mouse
: MS IntelliMouse®
DVD-ROM
Drive : 16X Max Variable DVD ROM •
CD-RW
: 8x/4x/32x CD-RW Drive,2nd Bay
Network Card
: Integrated 3Com® EtherLink® 10/100 Ethernet Controller • •
Modem
: 56K Telephony Modem for Windows ME •
COMP 4—Power Tools for the Mind Sound Card
: Turtle Beach Santa Cruz DSP
Speakers
: Altec Lansing THX Certified ADA885 Dolby Digital Speakers with Subwoofer
Bundled Software
and Access 2002) : Microsoft® Office XP Pro w/Money 2001(adds PowerPoint
Zip Drive
: 250MB Iomega Zip BUILT-IN Drive with One Disk
Media
: Imation CDR 700MB, 80 minute, 12X spindle 25-pack, 3-Pak of Iomega 100MB Zip Disks
Printers
: HP Deskjet 960 CSE
Power Protection
: APC Back UPS Office 500
Dell Movie Studio
: Dazzle Analog/Digital 1394 PCI Card
Scanners
: HP ScanJet 6300Cse
Digital Video Camera
: Intel Easy PC Camera Pack-Midnight Grey
PRICE: $4,089.00 – YIKES!
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Speed and storage capacity
• A little about
event
speeds: Milliseconds (thousandth)… Disk access Microseconds (millionth)…..Memory access Nanoseconds (billionth)……. Processor speed Picoseconds (trillionth)…….Supercomputer proc. speed • A little about
storage capacities
: Floppy disk……………………1.2 million characters Zip disk……………………….100 million characters Hard drive……………………...300
billion
characters
Hmm… How much is a billion?
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Time vs Frequency
• Hertz (Hz) means “number of times per second” • 1/time (sec) = frequency (Hz) 1/frequency (Hz) = time (sec) – If I can chop a log in 10 sec, that’s 0.1 Hz – If I can chop .1 logs per sec, that 1 log in 10 sec Typical computer times and frequencies: Milliseconds (thousandth) 1000 Hz Microseconds (millionth) Megahertz (MHz) Nanoseconds (billionth) Gigahertz (GHz) Picoseconds (trillionth) Terahertz (THz)
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Next Class
• History: How did we get here?
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