Why build a computer?

Computers were developed to mechanize mathematical computations.

Two definitions: A computer is “a programmable electronic device that

can store, retrieve, and process data.” - Merriam-Webster Dictionary, 2000

A computer is “one who computes; a reckoner; a calculator.” - Webster’s Dictionary, 1828

Computer History

Mechanical devices (past - 1890)

Electro-mechanical devices (1890 - 1942)

“Modern” Computers:1st Generation - Vacuum tubes (1942 - 1959)

2nd Generation - Transistors (1959 - 1965)

3rd Generation - Integrated Circuit (1965 - 1971)

4th Generation - Microprocessor (1971 -)

1642 Base-10 adding machine Carried one digit to the next Never really used

Blaise Pascal (1623-1662)“Pascaline”

1694 Base-10 multiplication machine Worked by repeated addition

Gottfried Leibniz (1646-1716)“Leibniz calculator”

1801 Weaved patterns

described by holes in punched cards

1st programmable device

Joseph-Marie Jacquard (1752-1834) “Jacquard’s loom”

1822 Calculated squares and

cubes using the method of differences

Base-10 Never completed

Charles Babbage (1793-1871)“Difference Engine”

Charles Babbage (cont.) “Analytical Engine”

1833 Primary innovation:

The difference engine was single-purpose

The analytical engine was general-purpose

Anticipated modern computers by: Separating processing from

storage Using punched cards for

input Was never built

A supporter and mentor of Babbage Translated material on the analytical engine Suggested that punched cards could “instruct” the

engine to perform and repeat operations The Ada programming language is named for her

Ada Augusta (1816-1852) “the first programmer”

Mechanized the 1890 US census

Worked by electronically counting one card per person

Formed a company that eventually became IBM

Herman Hollerith (1860-1929)“tabulating machine”

1942 The first electronic

computer Snubbed by IBM Never patented

John Atanasoff (1903-1995)“Atanasoff-Berry Computer (ABC)”

Other Early Computers

Colossus (1943 - Bletchley Park)

Used by the British to break German codes in WWII

ENIAC (1946 - U Pennsylvania)

Used by the US Army to compute artillery firing tables

Mark I (1944 - Harvard and IBM)Funded by the US Navy to compute navigation tables

Stored-Program Computers

ENIAC (1946 – U Pennsylvania) 18,000 vacuum tubes, hard-wired for task Used to compute artillery firing tables

von Neumann’s draft report (1945) “von Neumann” architecture

EDSAC (1949 - U Cambridge) The first large-scale stored-program machine Did not have to be rewired for a new task

John von Neumann

UNIVAC

An updated version of the ENIAC. Sold to the US census bureau and

delivered in 1951 Successfully predicted the outcome of

1952 presidential election based on early returns

IBM

UNIVAC’s success scared Thomas Watson, Jr.

IBM 700 series “Big Blue” held 75% of the

market by 1957 and dominated the industry for the next 25 years

PDP-8

Using transistors made computers smaller, faster, and more reliable

Digital Equipment Corporation (DEC) built the PDP series starting in 1960

The PDP-8, 1963, was the definitive mini-computer

IBM 360

Using integrated circuits made computers even smaller, and capable of being mass produced.

The IBM-360 series, starting in 1964, was the definitive IC computer.

The Personal Computer

Altair (1975) The Altair 8800 was the first affordable

personal computer 256 bytes of memory

Apple II (1977) IBM PC (1981) Apple Macintosh (1984) The PC Today (20__)