In the 1930s American mathematician Howard Aiken developed the Mark I calculating machine, which was built by IBM. This electronic calculating machine used relays and electromagnetic components to replace mechanical components. In later machines, Aiken used vacuum tubes and solid state transistors (tiny electrical switches) to manipulate the binary numbers. Aiken also introduced computers to universities by establishing the first computer science program at Harvard University. Aiken never trusted the concept of storing a program within the computer. Instead his computer had to read instructions from punched cards.

John Mauchly, an American physicist, and J. Presper Eckert, an American engineer, proposed an electronic digital computer, called the Electronic Numerical Integrator And Computer (ENIAC), which was built at the Moore School of Engineering at the University of Pennsylvania in Philadelphia. The computer was based on some concepts developed by John Atanasoff, a physics teacher at Iowa State College. ENIAC was completed in 1945 and is regarded as the first successful, general digital computer. It weighed more than 27,000 kg (60,000 lb), and contained more than 18,000 vacuum tubes.

Roughly 2000 of the computer's vacuum tubes were replaced each month by a team of six technicians. Many of ENIAC's first tasks were for military purposes, such as calculating ballistic firing tables and designing atomic weapons. Since ENIAC was initially not a stored program machine, it had to be reprogrammed for each task.

Unfortunately, although the conceptual design for EDVAC was completed by 1946, several key members including Eckert and Mauchley left the project to pursue their own careers, and the machine did not become fully operational until 1952. When it was finally completed, EDVAC contained approximately 4,000 vacuum tubes and 10,000 crystal diodes.

In light of its late completion, some would dispute EDVAC's claim-to-fame as the first stored-program computer. A small experimental machine (which was based on the EDVAC concept) consisting of 32 words of memory and a 5-instruction instruction set was operating at Manchester University, England, by June 1948. Another machine called the electronic delay storage automatic calculator (EDSAC) performed its first calculation at Cambridge University, England, in May 1949.

EDSAC contained 3,000 vacuum tubes and used mercury delay lines for memory.Programs were input using paper tape and output results were passed to a teleprinter. Additionally, EDSAC is credited as using one of the first assemblers called "Initial Orders," which allowed it to be programmed symbolically instead of using machine code.

Eckert and Mauchley eventually formed their own company, which was then bought by the Rand Corporation. They produced the Universal Automatic Computer (UNIVAC), which was used for a broader variety of commercial applications. The (UNIVAC I), was also based on the EDVAC design. Work started on UNIVAC I in 1948, and the first unit was delivered in 1951, which therefore predates EDVAC's becoming fully operational.

Eckert and Mauchly later lost the patent on their machine when it was claimed that another early experimenter, John Atanasoff, had given them all the ideas about ENIAC that mattered.

RELATED INFORMATION::
John Mauchly, Inventor Profile   from The Great Idea Finder
J. Presper Eckert, Inventor Profile   from The Great Idea Finder
History of Computing   from The Great Idea Finder
Invention of the Personal Computer   from The Great Idea Finder

ON THE BOOKSHELF:
100 Inventions That Shaped World History
by Bill Yenne, Morton, Dr. Grosser (Editor) / Paperback - 112 pages (1983) / Bluewood Books 
This book contains inventions from all around the world from microchips to fire. This is a really good book if you are going to do research on inventions.
The First Electronic Computer: The Atanasoff Story
by Alice R. Burks, Arthur W. Burks / Paperback: 400 pages / Univ of Michigan Pr (October 1989)
This book traces the ENIAC lineage directly to the ABC and J.V.Atansoff. If there are any Atanasoff skeptics out there, this book is the definitive prescription to win their minds.
Dream Machine: Exploring the Computer Age
by Jon Palfreman, Doron Swade / Paperback (October 1993) / Bbc Pubns
The Dream Machine provides a plethora of information to the reader. It gives specific detials of the
evolution of the computer. Including: many people, companies (IBM, Remington Rand), the
languages of programming, the personal computer and more.
ENIAC: The Triumphs and Tragedies of the World's First Computer
by Scott McCartney / Hardcover - 262 pages / Walker & Co
Eckert and Mauchly later lost the patent on their machine when it was claimed that another early experimenter, John Atanasoff, had given them all the ideas about ENIAC that mattered.
American Computer Pioneers
by Mary Northrup / Library Binding - 112 pages (July 1998) / Enslow Publishers, Inc.
This entry in the Collective Biographies series covers major players in the development of the computer, from Herman Hollerith, the inventor of punch cards, through the inventors of ENIAC and UNIVAC, as well as Bill Gates, Steve Jobs, and Marc Andreessen of Netscape.
From Memex to Hypertext: Vannevar Bush and the Mind's Machine
by James M. Nyce, Paul Kahn (Editor), Vannevar Bush / Hardcover - 367 pages (1992) / Academic Pr
Memex, a computer that was never built, was described in 1945 by pioneer computer engineer Bush, and foreshadowed the principles and operations of today's personal computers.

ON THE SCREEN:
The Creation of the Computer
DVD / 1 Volume Set / 50 Minutes / History Channel / 73090 / Less than $25.00
Trace the technological advancements that led to the first true modern "computers" and the rapid progress that saw computers shrink from room-sized monsters to the desktop units that are revolutionizing life in the '90s.
Computers
DVD / 1 Volume Set / 50 Minutes / History Channel / Less than $25.00 / Also VHS
The incredible breakthroughs and refinements that have marked the development of the computer are so familiar that they have lost some of their power to amaze.

ON THE WEB:
25th Anniversary for Microprocessor
Article by Myles White for the Toronto Star, Fast Forward, for November 17, 1996
(URL: www.computerwriter.com/archives/1996/sf171196.htm)
Computer History
ENIAC's underlying architecture was very different to that of modern computers.
(URL: www.maxmon.com/history.htm)
Computer
From the Microsoft Encarta Online Encyclopedia.
(URL: encarta.msn.com)
American Computer Museum
Located in Bozeman, Montana, USA is one of the world's largest and most comprehensive collection of computer and information age history anywhere on public display!
(URL: www.compustory.com/)
Birthplace of the Electronic Digital Computer
John Vincent Atanasoff and the Birth of the Digital Computer at Iowa State University
(URL: www.cs.iastate.edu/jva/jva-archive.shtml)
ENIAC is 55!
ENIAC's 55th birthday with the premiere of a new documentary feature on the invention of ENIAC entitled Mauchly: The Computer and the Skateboard. From University of Pennsylvania, Almanac.
(URL: www.upenn.edu/almanac/v47/n21/ENIAC.html)
ENIAC Facts
The invention of ENIAC opened up computer technology to all generations that have since followed.
(URL: www.annonline.com/interviews/990629/facts.html)
The History of Computing
This collection of materials relating to the history of computing is provided courtesy of Department of Computer Science, Virginia Tech, and is sponsored by a grant from the National Science Foundation
(URL: virtualmuseum.dlib.vt.edu/cgi-bin/Lobby?Method=Timeline)
San Diego Computer Museum
The mission of the Computer Museum of America is to preserve the major milestones in the development of the computer industry and to chronicle these milestones for the enrichment and education of all. Our exhibits highlight the history of data processing and the contributions of pioneers in the field.
(URL: www.computer-museum.org/index.html)
The Birth of the Information Age
An 18 month celebration of the invention and enduring impact of ENIAC, the world's first electronic, large scale, general-purpose computer, activated at the University of Pennsylvania in 1946.
(URL: homepage.seas.upenn.edu/~museum/)
The Computer Society
With nearly 100,000 members, the IEEE Computer Society is the world's leading organization of computer professionals.
(URL: www.computer.org/)
The ABC Computer
The contributions of an Iowa State College professor, John V. Atanasoff, who had designed and built an electronic computing device between 1937 and 1942 with the assistance of his graduate student, Clifford Berry. While there are some doubts as to whether the Atanasoff-Berry Computer (ABC) was ever fully operational, Mauchly visited Atanasoff during the summer of 1941 and had a close look at the machine. There is actually little doubt that Mauchly was inspired by Atanasoff's work. In 1941 Atanasoff knew more about basic elements of electronic computation than Mauchly and openly shared this knowledge.

DID YOU KNOW:

• In 1943, IBM's Thomas J. Watson, predicted that "there is a world market for about five computers."
• "Computers in the future may weigh no more than 1.5 tons." Popular Mechanics, forecasting the relentless march of science, 1949.
• "I have traveled the length and breadth of this country and talked with the best people, and I can assure you that data processing is a fad that won’t last out the year." The editor in charge of business books for Prentice Hall, 1957.
• "But what ... is it good for?" Engineer at the Advanced Computing Systems Division of IBM, 1968, commenting on the microchip.
• "There is no reason anyone would want a computer in their home." Ken Olson, president, chairman and founder of Digital Equipment Corp., 1977.
• ENIAC stands for Electronic Numerical Integrator And Computer.