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Introduction to Computing

      Computer History
• Gross Anatomy
  Hardware: equipment associated with the computer
     • Input devices, processor, output devices, storage
  Software: instructions that tell the hardware what to do
  Two categories of software:
     • System software
     • Application software
• Coordination of many levels (layers) of

                Application (ex: browser)
   Software                 (ex: Mac OSX)
                                            Instruction Set
   Hardware   Processor Memory I/O system     Architecture

                    Digital Design
                    Circuit Design
• Instruction Set Architecture
  Basic job of a CPU: execute lots of instructions
  Instructions are the primitive operations that the CPU
  may execute
  Different CPUs implement different sets of instructions
  The set of instructions a particular CPU implements is
  an Instruction Set Architecture (ISA)
     • Examples: Intel 80x86 (Pentium 4), IBM/Motorola PowerPC
       (Macintosh), MIPS, Intel IA64, ...

           instruction set

• von Neumann Architecture
  Although specific components may vary, virtually all
  modern computers have the same underlying structure
  known as the von Neumann architecture
  Named after computer pioneer, John von Neumann,
  who popularized the design in the early 1950's
• The von Neumann architecture identifies 3
  essential components:
  Input/Output Devices (I/O) allow the user to interact with
  the computer
  Memory stores information to be processed as well as
  programs (instructions specifying the steps necessary
  to complete specific tasks)
  Central Processing Unit (CPU) carries out the
  instructions to process information
• First “computer”?
  The first actual calculating mechanism known to us is
  the abacus, which was invented about 2000 years ago

Many references cite the French mathematician,
physicist, and theologian Blaise Pascal as being the
inventor of the first mechanical calculator in 1642, the
Arithmetic Machine
However, it now appears that the first mechanical
calculator may have been conceived by someone else
almost 150 years earlier than Pascal's machine. Can
you guess who?
   • Leonardo Da Vinci
In the early 1800s, a French silk weaver called Joseph-
Marie Jacquard invented a way of automatically
controlling the warp and weft threads on a silk loom by
recording patterns of holes in a string of cards
The first device that might be considered to be a
computer in the modern sense of the word was the
Difference Engine to automatically calculate
mathematical tables conceived in 1822 by the British
mathematician and inventor Charles Babbage

The Difference Engine was only partially completed
when Babbage conceived the idea of another, more
sophisticated machine called the Analytical Engine

The Analytical Engine was intended to use loops of
Jacquard's punched cards to control an automatic
calculator, which could make decisions based on the
results of previous computations
Working with Babbage was Augusta Ada Lovelace, the
daughter of the English poet Lord Byron. Ada, who was
a splendid mathematician and one of the few people
who fully understood Babbage's vision, created a
program for the Analytical Engine

Ada is now credited as being the first computer
programmer and, in 1979, a modern programming
language was named ADA in her honor
In 1939, a German engineer, Konrad Zuse built the first
programmable, general-purpose digital computer. His
computer was built from electric relays to automate
engineering calculations
   • “I was too lazy to calculate and so I invented
     the computer.”

John Atanasoff invented the Atanasoff-Berry Computer
(ABC) —the first electronic digital computer. Built in
1939, this computer used vacuum tubes and was based
on binary arithmetic. It was never a fully operational
In 1944, Howard Aiken completed the Mark I, the
largest electromechanical calculator ever built. It was
built with electromechanical relays and followed
instructions punched in paper tape
• The first computer “bug”
In 1945, Mauchly and Eckert built the ENIAC (Electronic
Numerical Integrator and Computer). The ENIAC was
built with 18,000 vacuum tubes that failed on an
average of once every seven minutes

After the war, they created the UNIVAC I - the first
general-purpose commercial computer
• First-Generation Computers
  1930s – 1940s
  Vacuum tubes used as switches
  Large computers
  Extremely slow by today’s standards
  Prone to frequent failure
  Includes the ABC, Mark I, ENIAC, UNIVAC,
  and others of similar design
• Second-Generation Computers
  1950s – mid-1960s
  Transistors used as switches
  Smaller than vacuum-tube-built computers
  As much as a thousand times faster than
    first-generation computers
  More reliable and less expensive
• Third-Generation Computers
  Late 1960s
  Hundreds of transistors packed into a single integrated
  circuit on a silicon chip
  Dramatic reduction in size and cost
  Significant increases in reliability, speed, and efficiency
  Mass production techniques to manufacture chips
• Fourth-Generation Computers
  1970s to present
  Complete computer on a chip
  Radical change in the appearance, capability and
  availability of computers
• Technology Trends: Microprocessor Complexity
 # of transistors on an IC

                                           Gordon Moore
                                          Intel Cofounder

                                    2X Transistors / Chip
                                    Every 1.5 years

                                    Called “Moore’s Law”


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