CS 302
Ch. 1 The Big Picture
1.1 Computing Systems
Computing system: computer hardware, software, and data,
which interact to solve problems
Computer hardware: the collection of physical elements that
make up the machine and its related pieces: boxes, circuit
boards, chips, wires, disk drives, keyboards, monitors,
printers, and so on.
Computer software: the collection of programs that provide
the instructions that a computer carries out
Layers of a Computing System
Information (innermost layer)- reflects the way we
represent info. on a computer; info. on a computer is
managed using binary digits, 1 and 0; types of info. we
manage: numbers, text, images, audio, video
Hardware (next layer)- consists of the physical hardware of
a computer system; includes devices such as gates and
circuits, which control the flow of electricity in
fundamental ways; Central Processing Unit (CPU), memory
Programming (next layer)- deals with software, the
instructions used to accomplish computations and manage
data; programs take many forms, performed at many levels,
implemented in many languages; goal is to solve problems
Operating system (OS)( next layer)- helps manage the
computer’s resources; Windows XP, Linux, Mac OS; help us
interact with the computer system and manage the way
hardware devices, programs, and data interact
Applications (outer layer)- focuses on using the computer
to solve specific real-world problems; run application
programs to take advantage of the computer’s abilities in
other areas, such as helping us design a building or play a
game; The spectrum of area-specific computer software tools
if far-reaching and involves specific sub disciplines of
computing, such as information systems, artificial
intelligence, and simulation Communications (outmost layer)- computers are connected
into networks so they can share information and resources;
the Internet
Abstraction: a mental model that removes complex details;
ex. the levels of a computing system
-Miller’s law: a human being can actively manage about
7 (+/- 2 depending on the person) pieces of information in
short-term memory at one time
-Ex.: driving a car; we don’t need to know how a car
works (the engine in detail) to drive one; you only need to
know some basics about how to interact with the car
(pedals, knobs, steering wheel)
-the key to computing; the layers of a computing
system embody the idea of abstraction
1.2 The History of Computing
A Brief History of Computing Hardware
Early History
-the Stonehenge, the abacus (16 thB.C), mechanical
machines that did addition and subtraction (middle 17 ), th
mechanical device to do four whole-number operations (late
17 ), Jacquard’s Loom/ punched card (late 18 ) th
-Charles Babbage’s analytical engine: too complex for
him to build for the technology of his time; his vision
included memory and the input of both numbers and
mechanical steps, making use of punched cards
-Ada Augusta/ Countess of Lovelace: first programmer;
the concept of the loop-a series of instructions to repeat;
programming language Ada
-mechanical adding machine (late 19 ), electro-
magnetic tabulator- read info. from punched card- U.S.
census (early 20 )th
-Turing machine (1936): an abstract mathematical model
-World War II: Harvard Mark I, ENIAC, EDVAC (1950),
UNIVAC I (1951)- first computer used to predict outcome of
presidential election
First Generation (1951-1959)
-commercial computers built using vacuum tubes to
store info.; a
vacuum tube generated a great deal of heat and not
very reliable;
required very large, specially built rooms with air-
conditioning -magnetic drum: primary memory device that rotated
under a read/
write head; when the memory cell that was being
accessed rotated, data was written to or read from
that place
-inpute device was a card reader that read the holes
punched in an
IBM card; output device was a punched card or a line
printer
-magnetic tape drives: sequential storage devices; the
data on the
tape much be accessed one after another in a linear
fashion
-auxiliary storage devices: storage devices external
to the computer
memory; ex. magnetic tape
-peripheral devices: input devices, output devices,
auxiliary storage
devices
Second Generation (1959-1965)
-transistor: replaced the vacuum tube as the main
component in
the hardware; smaller, more reliable, more durable,
and cheaper
-advent of immediate access memory; magnetic cores:
tiny dough-
nut shaped devices, capable of storing one bit of
information; cores
strung together w/ wires to form cells, and cells
combined to form
a memory unit; device was motionless and accessed
electronically
-magnetic disk: new auxiliary storage device; faster
than the mag-
netic tape b/c each data item accessed directly by
referring to its
location on the disk; organized so each piece of data
has own location
identifier (an address)
Third Generation (1965-1971)
-integrated circuits (ICs): solid pieces of silicon
that contained the
transistors, other components, and their connections;
much smaller,
nd cheaper, faster, reliable than printed circuit boards
(2 gen.) -Moore’s law: the # of circuits that could be placed
on a single
integrated circuit was doubling each year
-IC technology allowed memory boards to be built using
transistors
-Aux. storage devices still needed because transistor
memory was
volatile (info. went away when power turned off)
-terminal: an input/output device w/ a keyboard and a
screen intro-
duced; keyboard gave user direct access to computer,
screen
provided an immediate response
Fourth Generation (1971-?)
-Large-scale integration
-several thousand transistors on a silicon chip
-Moore’s law: chip density was doubling every 18 months
-personal computer (PC): microcomputers become so
cheap that
anyone could have one; kids played Pac Man
-Apple
-IBM PC (1981); Apple Macintosh (1984)
-workstations: mid 1980s; larger, more powerful
machines generally
meant for business; workstations connected by cables,
or networked
so they could interact w/ each other
-machine language: set of instructions each computer
was designed
to understand
-RISC chip: Reduced-Instruction-Set-Computer
-Moore’s law: Computers will either double in power at
the same
price or halve in cost for the same power every 18
months
parallel architectures: rely on a set of interconnected
central processing
units rather and a single primary
processing unit
-offer several ways to increase the speed of
execution; a given step
in a program can be separated into multiple pieces,
and those
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