History of “Computers”
• Manual calculators
– Humans implemented the algorithm
• Abacus (at least 2000 years old)
• Slide rule (developed about 1621)
• Mechanical (manually powered) calculators
– Algorithm is part of the device’s mechanical
construction
– 1623 Schikard’s Calculator
– 1642 Pascal”s Pascaline
– 1673 Leibniz Calculator
– 1820 Colmar’s Arithmometer – first mass produced
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Steam powered calculator
• Charles Babbage (1822-1830s)
– He had neither the money nor the technology
for his ideas, but his device was to have a
memory, programmable processor, programs
and data input through punched cards
• Countess of Lovelace (Ada Byron), a
trained mathematician, wrote programs
– Also financed Babbage (to her financial ruin)
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Punched cards
• Jacquard used punched cards to control the
pattern of weaving looms – 1700s
• Hollerith used punched cards for the 1890
census
– Hollerith’s Tabulating Machine Company
became International Business Machines in
1924
• NCR, Olivetti, Burroughs, Remington all
developed business machines
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Modern Computers
• Atanasoff-Berry Computer 1937-1942
–
–
–
–
–
Vacuum tubes for processing circuitry
Binary number system
All electronic (no mechanical components)
Digital
Never patented
• Atanasoff called to Washington for war effort
– Constructed a working prototype
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ENIAC and UNIVAC
• Mauchley visited Atanasoff in Iowa
• Eckert-Mauchley developed computers
based on same principles
– UNIVAC was first commercially successful
digital computer
– Acquired by Remington Rand, which became
Sperry Rand
• Sperry Rand tried to patent the architecture
• Atanasoff/Berry sued and won
– Berry died mysteriously
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COLOSSUS
• British computer used during WWII
• 1943-1945
– Vacuum tubes, binary arithmetic, electronic
– Cracked German Enigma code
– Alan Turing had a major part
• Turing machine
– The COLOSSUS had no influence on
development of computers - kept secret
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Early computers
• “First generation” digital computers
• Occupied an entire room
• Vacuum tubes controlled the flow of data
–
–
–
–
Generated a lot of heat
Wore out quickly; also leaked
As large as a large light bulb
By the late 1940's, large computers contained thousands of vacuum
tubes and took up perhaps100 square meters of space.
• Analog computers were also developed
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Software for 1st generation computers
• Programming was in machine code
– 0s and 1s
• An instruction such as 001 11001 might mean
get (001) the value from address 11001 and place in some
implicit location – a register or memory location
• Then assembly language was developed
– A program translated mnemonics such as “get” to 001
• These programs were difficult to write and debug
• They were not portable since machine language is specific to a
machine’s architecture
• Programs were custom developed for specific application
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Second Generation Computers
• Transistors developed at Bell Labs
beginning in 1947
– Used in portable radios, then TVs
• Radio was a big part of US entertainment in 1940s
– Regulated current or voltage flow to switch
data between registers and memory
– Cheaper, smaller, more reliable, used less
power than vacuum tubes
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Software for 2nd generation computers
• In early systems, programmers wrote their
own input/output routines
– Most of the applications were computational
and i/o was limited
• i/o is the most repetitive, tedious part of
programming
• Operation Systems first developed as i/o
monitors – performing i/o for all programs
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Software for 2nd generation computers
• Development of “high-level” languages
– Fortran (computation), Lisp (artificial
intelligence), and Cobol (business applications)
• All three (updated) are still in use today, with Cobol
perhaps the most common
• Compilers or interpreters translate
programmer code to machine language
– Programs are portable if there exists a compiler
for their language for various architectures
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rd
3
generation computers
• Development of integrated circuits
– Thousands of transistors, resistors, diodes,
capacitors manufactured and connected
together, packed onto a miniaturized chip.
– Cheaper, faster [reduced latency of signals
sent], smaller, less power needed
– IBM built the 360 Mainframe computers
– Digital Equipment Corp. built PDP minis
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rd
3
generation software
• Software engineering
– Development of tools and designs to make
programming an engineering discipline
– Structured programming
– Modular programming
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th
4
generation computers
• Development of personal computers and
networks
– 1971 first general-purpose microprocessor
– 1975 – first commercial microprocessor (kit)
» Altair developed by Ed Roberts for MITS
– 1969 – Arpanet
– 1971 Intel 4004 microprocessor was
considerably less than a cubic inch in size but
had the power of ENIAC
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th
4
generation software
• Development of application programs for
personal computers
• Spreadsheets, word processing
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Apple computer
• Commodore, Atari, RadioShack, Timex
sold preassembled kits
– Applications were limited
• Kits are still used by hobbyists
• Steve Jobs and Steve Wozniak released
Apple I – 1976
– A kit contained 4kB RAM and cost $666
– About half the cost of the Volkswagen Beetle
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Growth of Personal Computers
• IBM marketed the Personal Computer 1981
• User communicated with OS via command
line
• Applications made personal computers
popular for small businesses
– VisiCalc, then Lotus spreadsheets
– Electric Pencil, Wordstar Wordperfect for
word processing
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PCs
• IBM did not retain rights to the OS for the
PC (PC-DOS)
– Control kept by Bill Gates, Microsoft
• Other companies manufactured clones of
the PC, on which MS-DOS ran
• IBM thought that the major value of PCs
was the hardware
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GUI
• Xerox Alto computers, GUI developed by
Xerox but not patented.
• Apple Lisa “borrowed” the GUI for their
Apple Lisa (1983), then used for the
cheaper Apple Macintosh (1984).
• Windows OS developed by Microsoft
– Ran on all PC-compatible machines
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Killer App
• The general public was still not buying
personal computers – expensive, still not
that easy to use
• The “killer app” was the Internet
– Spread to commercial use by the late 1980s
• GUI browser
• ISPs provided inexpensive connections
• Development of e-commerce sites
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Computers today
• Positive effects include:
–
–
–
–
Communication
Education
E-Commerce
Social Networking
• Negative effects include
• Video Games/ gambling
• Privacy and security issues
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Professional Ethics
• What are your standards for conduct when
you are on-the-job or during schoolwork?
• How do your ethics relate to the law?
– Laws are (or should be) legislated codes of
conduct based on what is considered the
community’s ethics
• Some behavior is legal but not ethical
• Some laws, or their implementations, are
not ethical
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Some computer-related laws
• See text p. 524
– 1976 – extended copyright law
– Fair use doctrine for education or personal use
• Limited usage of copyrighted material
– 1984 Companies are not responsible for user
misuse of purchased equipment
– 1986 Computer Fraud and Abuse Act
• It is a criminal offense to knowingly access a
computer without authorization, or cause damage
resulting from infringement
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More relevant U.S. Laws
• 1998 Digital Millennium Copyright Act
– Illegal to circumvent, or to assist in
circumventing mechanisms to prevent copying
copyrighted material
• 2003 CAN-SPAM Act
– Requires senders of commercial e-mail to
attach a valid subject line as well as the
sender’s legitimate physical address.
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Some issues to be discussed
• Privacy – encryption, secure authorized access
• Use of copyrighted and licensed material
– watermarks
• Use of work computers for personal
business – distribute company policies
• Hacking – laws and prosecution
• Whistle blowing – policy for anonymous
whistlebrowing
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Forensics
• Computer forensics is the “scientific
examination and analysis of data located on
computer storage media, conducted to offer
evidence of computer crimes in court.
1) Crimes that use computers (violating
copyrights, child pornography, identity
theft)
2) Attacking computers (DDoS, destructive
viruses, vandalizing web sites)
Forensics Techniques
• Copy disk image to a STERILE write-once
medium
• Original disk is secured and saved
• Data recovery software can retrieve deleted
information
• Temporary Internet files show the visited sites
– You can delete these
– Browser/tools or temporary internet files
• Virtual memory caches hold parts of files
Catching cybercriminals
• Honeypots
– Attract cybercriminals to web sites,
“vulnerable” computer systems
• Place government agents in web groups
• Gather information on organized crime
– Follow the money trail
– Collect and analyze data
– Create site (e.g., the Internet Crime Claim
Center) for victims
Work Safety/ radiation exposure
• Radiation risks
– Cell phone towers/ cell phones
• Check radiation level (SAR-specific absorption rate)
• Use hands-free headset
– Wireless networks/ electrical appliances
– Computer Screens/ TV screens
• Radiation is primarily low frequencies and degrades
quickly (say within 20 inches – or an arm’s length)
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Work Safety/ ergonomics
• Ergonomics is the study of how to create
safe (working) environments
– Repetitive stress can cause stiffness, pain, and
injuries to tendons, muscles, and nerves
– Carpal tunnel syndrome – compression of the
nerves controlling your thumb and index finger
mainly. Affects your wrist as well.
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Ergonomics
• Monitor should be arm’s length from your
body – 18” to 22”
• Keyboard slightly tilted away from your
body
• Keyboard above your lap
• Mouse at some highly as your keyboard
• Walk around periodically
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Ergonomics for mobile phones
• Smart phones should NOT be used for extended computer
activity
• “Use hands free devices to eliminate awkward, static
postures ‐ especially during long phone calls.
• Limit duration and frequency of calls, texts, and emails.
• Maintain neutral wrist posture and alternate hands when
holding devices.
• Reduce keystrokes with text shortcuts (search “text
shortcuts” on your web browser or app store), or where
feasible, use speech‐recognition applications.”
•
http://www.stanford.edu/dept/EHS/prod/general/ergo/documents/laptop_guide.pdf
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Provenance
• Provenance is the “origin and history” of an
object [from text] {pedigree?}
• Web sources
– URLs, peer reviewed, ads, authors can be useful
– Original or reposted material (are the same phrases
used in many other postings)
– Dates
– Doctored photos
– Contact information provided
– Login required?
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