Transcript Chapter 3 - Faculty Personal Web Page

Chapter 3
Computer Hardware
II. A Brief History of Computer
Hardware
Without computers many technological
achievements would not have been
possible:
Counting with fingers/toes
Blaise Pascal, 1642 – invented the first
mechanical adding machine
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A Brief History of Computer Hardware
Herman Hollerith –
Hollerith’s Punch Card
system to record
census data in late
1880’s; 1911 – merged
with competitor to
form IBM
ENIAC (Electronic
Numerical Integrator
and Calculator), 1946
– the world’s first
electronic digital
computer
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II. A Brief History of Computer
Hardware
1950’s – Transistors were invented
and replaced tubes
1958 – Integrated Circuit (“chip”) was
invented
1970’s – 1980’s
Further miniaturization of circuits
Apple Computer and IBM PC
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III. Types of Computer Systems
Computers come in a variety of sizes,
shapes, and computing capabilities –
Mainframes
Midrange (obsolete due to powerful
microcomputers)
Microcomputers
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IV. Microcomputer Systems
(Personal Computer)
The most important category for
businesses and consumers, exceeds the
power of many mainframes
Workstations – support mathematical and
graphical demands
Network Servers – support
telecommunications and resource sharing
Computer Terminals – any device that
allows access to a computer
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IV. Microcomputer Systems (Personal
Computer)
Network Computers – designed specifically
for use with networks and the Internet; low
TCO (total cost of ownership)
Information Appliances – Web-enabled
devices for accessing information from
anywhere – cell phones, PDAs, handheld
PCs
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Corporate PC Criteria
Why laptops instead of desktops?
Why would a change in OS be
disruptive?
What are the strengths vs. risks of
cabled vs. wireless PCs?
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V. Midrange, Mainframe, and
Supercomputer Systems
Midrange Systems – popular as Network
Servers; disappearing due to
microcomputers
Mainframe Systems – large, fast, and
powerful, used for high transaction
processing and complex computations; used
by corporations and government agencies
Supercomputers – extremely powerful,
extremely high speeds and massive numeric
computations
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V. Midrange, Mainframe, and
Supercomputer Systems
The Next Wave of Computing –
minisupercomputers; connecting all the
power of unused desktops in an
organization
 Distributed (Grid) Computing – parallel
computing over a network
Advantages – purchase nodes as a commodity,
economies of scale
Disadvantages – untrustworthy calculations, lack of
centralized control
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The Computer System
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VII. Moore’s Law
Moore’s Law 1965 – the
number of transistors on
a chip will double every
18-24 months –
essentially, the power or
speed of a computer will
double every 18-24
months
The Price would halve in
that same time, which
has also proven to be
true
Recent statistics indicate
this time has decreased
to 12 months
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Section 2
Computer Peripherals: Input, Output, and
Storage Technologies
Peripheral - a generic name for all input,
output, and secondary storage devices not
part of the CPU (basically, what is
connected to the outside of the computer)
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II. Input technologies
Input Devices – keyboards, mice, light
pens, trackballs, touch screens
Speech Recognition Systems –
understands spoken commands/words
Discrete Speech Recognition – speak each word
separately
Continuous Speech Recognition – recognizes
conversationally-paced speech
Speaker-Independent Voice Recognition –
understands speech from a voice it has never
heard before
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II. Input technologies
Optical Scanning – converts text or
graphics to digital input for direct entry
of source documents
Other Input Technologies
Magnetic Stripe – on credit cards
Smart Cards – contain an embedded chip
Digital Cameras
Magnetic Ink Character Recognition (MICR)
– used in banking industry
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Forget the ATM: Deposit Checks Without
Leaving Home
What does federal Check 21 Act allow?
What is the concern of consumers
remotely depositing checks?
What basic security is provided?
What limits/restrictions are placed on
the consumers?
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IV. Storage Tradeoffs
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IV. Storage Tradeoffs
Direct and Sequential Access
Direct Access and Random Access are the same
concept; locate an address on the storage
device and go directly to that location for data
access
Sequential Access – All tape devices are
accessed serially – device must be read one
record at a time from the data until the desired
data is found
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VI. Magnetic Disks – Hard drives are the
most common form of secondary storage
RAID (Redundant Arrays of Independent Disks)
Storage – interconnected groups of hard drives
- fast speeds and fault tolerant (redundant
backups)
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V. Semiconductor Memory
RAM (Random Access Memory) – volatile, may
be read and over-written
ROM (Read Only Memory) – non-volatile, may
be read but not over-written or erased; PROM
and EPROM may be reprogrammed
Flash (Jump) Drives – solid-state memory
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IV. Storage Tradeoffs
Computer Storage Fundamentals
Binary Representation – Two-state, on/off, +/-,
0/1
Bit – Binary digit, 0/1
Byte – Grouping of bits (typically 8 bits/byte),
represents a single character
ASCII – formalized code determining what byte
values represent which character
Storage capacities – kilobytes (KB), megabytes
(MB), gigabytes (GB), terabytes (TB)
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Representing characters in bytes
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VII & VIII. Magnetic Tape & Optical Disks
Magnetic Tape – slow speeds, but
inexpensive for large amounts of
backups
Optical Disks – CD-ROM, CD-R, DVD-R
(cannot be erased or re-written); CD-RW,
DVD-RW (may be erased or re-written)
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VII. Radio Frequency Identification (RFID)
RFID – for tagging and identifying mobile objects
(store merchandise, postal objects, sometimes
living organisms); provides information to a
reader when requested
Passive – no power source, derives power from the
reader signal
Active – self-powered, do not need to be close to the
reader
RFID Privacy Issues – may be used as spychips; gathers
sensitive information about an individual without
consent
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