Computer History

The First Freely Programmable Computer invented by Konrad Zuse

Konrad Zuse (1910-1995) was a construction engineer for the Henschel Aircraft Company in Berlin, Germany at the beginning of WWII. Konrad Zuse earned the semiofficial title of "inventor of the modern computer" for his series of automatic calculators, which he invented to help him with his lengthy engineering calculations. Zuse has modestly dismissed the title while praising many of the inventions of his contemporaries and successors as being equally if not more important than his own.

One of the most difficult aspects of doing a large calculation with either a slide rule or a mechanical adding machine is keeping track of all intermediate results and using them, in their proper place, in later steps of the calculation. Konrad Zuse wanted to overcome that difficulty. He realized that an automatic-calculator device would require three basic elements: a control, a memory, and a calculator for the arithmetic.

In 1936, Zuse made a mechanical calculator called the Z1, the first binary computer. Zuse used it to explore several groundbreaking technologies in calculator development: floating-point arithmetic, high-capacity memory and modules or relays operating on the yes/no principle. Zuse's ideas, not fully implemented in the Z1, succeeded more with each Z prototype.

In 1939, Zuse completed the Z2, the first fully functioning electro-mechanical computer.

Konrad Zuse completed the Z3 in 1941, with recycled materials donated by fellow university staff and students. This was the world's first electronic, fully programmable digital computer based on a binary floating-point number and switching system. Zuse used old movie film to store his programs and data for the Z3, instead of using paper tape or punched cards. Paper was in short supply in Germany during the war.

According to "The Life and Work of Konrad Zuse" (by Horst Zuse)

In 1941, the Z3 contained almost all of the features of a modern computer as defined by John von Neumann and his colleagues in 1946. The only exception was the ability to store the program in the memory together with the data. Konrad Zuse did not implement this feature in the Z3, because his 64-word memory was too small to support this mode of operation. Due to the fact that he wanted to calculate thousands of instructions in a meaningful order, he only used the memory to store values or numbers.

The block structure of the Z3 is very similar to a modern computer. The Z3 consisted of separate units, such as a punch tape reader, control unit, floating-point arithmetic unit, and input/output devices.

Konrad Zuse wrote the first algorithmic programming language called 'Plankalkül' in 1946, which he used to program his computers. (He wrote the world's first chess-playing program using Plankalkül.)

The Plankalkül language included arrays and records and used a style of assignment (storing the value of an expression in a variable) in which the new value appears in the right column. An array is a collection of identically typed data items distinguished by their indices (or "subscripts"), for example written something like A[i,j,k], where A is the array name and i, j and k are the indices. Arrays are best when accessed in an unpredictable order. This is in contrast to lists, which are best when accessed sequentially.

Zuse was unable to convince the Nazi government to support his work for a computer based on electronic valves. The Germans thought they were close to winning the War and would not support further research. Zuse left for Zurich to finish his work (the Z4) and later moved to the United States, where he formed his own company for the construction and marketing of his designs.

The Z4 was finished in 1949 and escaped destruction. The Z1 through Z3 models were destroyed during the war (Zuse later rebuilt models of the Z3 in 1960 and the Z1 in 1984). Zuse smuggled the Z4 from Germany in a horse-drawn cart, which he hid in stables on route to Zurich, Switzerland. He completed and installed the Z4 in the Applied Mathematics Division of Zurich's Federal Polytechnical Institute. It was in use there until 1955. The Z4 had a mechanical memory with a capacity of 1,024 words and several card readers. Zuse no longer had to use movie film to store programs; he could now use punched cards. The Z4 had punches and various facilities to enable flexible programming including address translation and conditional branching.

By Mary Bellis

The Atanasoff-Berry Computer the First Electronic Computer - John Atanasoff and Clifford Berry

"I have always taken the position that there is enough credit for everyone in the invention and development of the electronic computer" - John Atanasoff to reporters.

Professor John Atanasoff and graduate student Clifford Berry built the world's first electronic-digital computer at Iowa State University between 1939 and 1942. The Atanasoff-Berry Computer represented several innovations in computing, including a binary system of arithmetic, parallel processing, regenerative memory, and a separation of memory and computing functions.

Presper Eckert and John Mauchly were the first to patent a digital computing device, the ENIAC computer. A patent infringement case (Sperry Rand Vs. Honeywell, 1973) voided the ENIAC patent as a derivative of John Atanasoff's invention. Atanasoff was quite generous in stating, "there is enough credit for everyone in the invention and development of the electronic computer." Eckert and Mauchly received most of the credit for inventing the first electronic-digital computer. Historians now say that the Atanasoff-Berry computer was the first.

"It was at an evening of scotch and 100 mph car rides," John Atanasoff told reporters, "when the concept came, for an electronically operated machine, that would use base-two (binary) numbers instead of the traditional base-10 numbers, condensers for memory, and a regenerative process to preclude loss of memory from electrical failure.”

John Atanasoff wrote most of the concepts of the first modern computer on the back of a cocktail napkin. He was very fond of fast cars and scotch.

In late 1939, John Atanasoff teamed up with Clifford Berry to build a prototype. They created the first computing machine to use electricity, vacuum tubes, binary numbers and capacitors. The capacitors were in a rotating drum that held the electrical charge for the memory. The brilliant and inventive Berry, with his background in electronics and mechanical construction skills, was the ideal partner for Atanasoff. The prototype won the team a grant of $850 to build a full-scale model. They spent the next two years further improving the Atanasoff-Berry Computer. The final product was the size of a desk, weighed 700 pounds, had over 300 vacuum tubes, and contained a mile of wire. It could calculate about one operation every 15 seconds, today a computer can calculate 150 billion operations in 15 seconds. Too large to go anywhere, it remained in the basement of the physics department. The war effort prevented John Atanasoff from finishing the patent process and doing any further work on the computer. When they needed storage space in the physics building, they dismantled the Atanasoff-Berry Computer. - by Mary Bellis

The Harvard Mark I Computer

Howard Aiken and Grace Hopper designed the MARK series of computers at Harvard University. The MARK series of computers began with the Mark I in 1944. Imagine a giant roomful of noisy, clicking metal parts, 55 feet long and 8 feet high. The 5-ton device contained almost 760,000 separate pieces. Used by the US Navy for gunnery and ballistic calculations, the Mark I was in operation until 1959.

The computer, controlled by pre-punched paper tape, could carry out addition, subtraction, multiplication, division and reference to previous results. It had special subroutines for logarithms and trigonometric functions and used 23 decimal place numbers. Data was stored and counted mechanically using 3000 decimal storage wheels, 1400 rotary dial switches, and 500 miles of wire. Its electromagnetic relays classified the machine as a relay computer. All output was displayed on an electric typewriter. By today's standards, the Mark I was slow, requiring 3-5 seconds for a multiplication operation.

Howard Aiken
Born: 9 March 1900 in Hoboken, New Jersey, USA
Died: 14 March 1973 in St. Louis, Missouri, USA
•Howard Aiken was an electrical engineer and physicist who first conceived of an electro-mechanical device like the Mark I in 1937. After completing his doctorate at Harvard in 1939, Aiken stayed on to continue the computer's development. IBM funded his research. Aiken headed a team of three engineers including Grace Hopper.
• The Mark I reached completion in 1944.
• In 1947, Howard Aiken completed the Mark II, an electronic computer. The same year he founded the Harvard Computation Laboratory.
• He later published numerous articles on electronics and switching theory and started Aiken Industries.
• Howard Aiken loved computers, but even he had no idea of their eventual widespread appeal. "Only six electronic digital computers would be required to satisfy the computing needs of the entire United States," he said in 1947.

Grace Hopper
Born: 9 Dec 1906 in New York, USA
Died: 1 Jan 1992 in Arlington, Virginia, USA
• Grace Hopper studied at Vassar College and Yale and then joined the Naval Reserve in 1943. In 1944, she started working with Aiken on the Harvard Mark I computer.
• Grace Hopper is responsible for the term 'bug' for a computer fault. The original 'bug' was a moth, which caused a hardware fault in the Mark I. Hopper was the first person to 'debug' a computer.
• In 1949, Grace Hopper started research for the Eckert-Mauchly Computer Corporation where she designed an improved compiler and was part of the team which developed Flow-Matic, the first English-language data processing compiler.
• She invented the language APT and verified the language COBOL.
• Grace Hopper was the first computer science "Man of the Year" in 1969.
• In 1991, Grace Hopper received the National Medal of Technology. - by Mary Bellis

The ENIAC I Computer - J Presper Eckert and John Mauchly

In 1946, John Mauchly and J Presper Eckert developed the ENIAC I (Electrical Numerical Integrator And Calculator). The U.S. military sponsored their research; they needed a calculating device for writing artillery-firing tables (the settings used for different weapons under varied conditions for target accuracy). The Ballistics Research Laboratory, or BRL (the branch of the military responsible for calculating the tables), heard about John Mauchly's research at the University of Pennsylvania's Moore School of Electrical Engineering. John Mauchly had previously created several calculating machines, some with small electric motors inside. He had begun designing (1942) a better calculating machine based on the work of John Atanasoff that would use vacuum tubes to speed up calculations.

On May 31, 1943, the military commission on the new computer began; John Mauchly was the chief consultant and J Presper Eckert was the chief engineer. Eckert was a graduate student studying at the Moore School when he met John Mauchly in 1943. It took the team about one year to design the ENIAC and 18 months and 500,000 tax dollars to build it. By that time, the war was over. The ENIAC was still put to work by the military doing calculations for the design of a hydrogen bomb, weather prediction, cosmic-ray studies, thermal ignition, random-number studies and wind-tunnel design.

The ENIAC contained 17,468 vacuum tubes, along with 70,000 resistors, 10,000 capacitors, 1,500 relays, 6,000 manual switches and 5 million soldered joints. It covered 1800 square feet (167 square meters) of floor space, weighed 30 tons, consumed 160 kilowatts of electrical power, and, when turned on, caused the city of Philadelphia to experience brownouts.

In one second, the ENIAC (one thousand times faster than any other calculating machine to date) could perform 5,000 additions, 357 multiplications or 38 divisions. The use of vacuum tubes instead of switches and relays created the increase in speed, but it was not a quick machine to re-program. Programming changes would take the technicians weeks, and the machine always required long hours of maintenance. As a side note, research on the ENIAC led to many improvements in the vacuum tube.

In 1948, Dr. John Von Neumann made several modifications to the ENIAC. The ENIAC had performed arithmetic and transfer operations concurrently, which caused programming difficulties. Von Neumann suggested that switches control code selection so pluggable cable connections could remain fixed. He added a converter code to enable serial operation.

In 1946, J Presper Eckert and John Mauchly started the Eckert-Mauchly Computer Corporation. In 1949, their company launched the BINAC (BINary Automatic) computer that used magnetic tape to store data.

In 1950, the Remington Rand Corporation bought the Eckert-Mauchly Computer Corporation and changed the name to the Univac Division of Remington Rand. Their research resulted in the UNIVAC (UNIVersal Automatic Computer), an important forerunner of today's computers.

In 1955, Remington Rand merged with the Sperry Corporation and formed Sperry-Rand. Eckert remained with the company as an executive and continued with the company as it later merged with the Burroughs Corporation to become Unisys.

J Presper Eckert and John Mauchly both received the IEEE Computer Society Pioneer Award in 1980.

At 11:45 p.m., October 2, 1955, with the power finally shut off, the ENIAC retired.

The UNIVAC Computer - J. Presper Eckert and John Mauchly

The Universal Automatic Computer or UNIVAC was a computer milestone achieved by Dr. Presper Eckert and Dr. John Mauchly, the team that invented the ENIAC computer.

J Presper Eckert and John Mauchly, after leaving the academic environment of The Moore School of Engineering to start their own computer business, found their first client was the United States Census Bureau. The Bureau needed a new computer to deal with the exploding U.S. population (the beginning of the famous baby boom). In April 1946, a $300,000 deposit was given to Eckert and Mauchly for the research into a new computer called the UNIVAC.

The research for the project proceeded badly, and it was not until 1948 that the actual design and contract was finalized. The Census Bureau's ceiling for the project was $400,000. J Presper Eckert and John Mauchly were prepared to absorb any overrun in costs in hopes of recouping from future service contracts, but the economics of the situation brought the inventors to the edge of bankruptcy.

In 1950, Eckert and Mauchly were bailed out of financial trouble by Remington Rand Inc. (manufacturers of electric razors), and the "Eckert-Mauchly Computer Corporation" became the "Univac Division of Remington Rand." Remington Rand's lawyers unsuccessfully tried to re-negotiate the government contract for additional money. Under threat of legal action, however, Remington Rand had no choice but to complete the UNIVAC at the original price.

On March 31, 1951, the Census Bureau accepted delivery of the first UNIVAC computer. The final cost of constructing the first UNIVAC was close to one million dollars. Forty-six UNIVAC computers were built for both government and business uses. Remington Rand became the first American manufacturers of a commercial computer system. Their first non-government contract was for General Electric's Appliance Park facility in Louisville, Kentucky, who used the UNIVAC computer for a payroll application.

J Presper Eckert and John Mauchly's UNIVAC was a direct competitor with IBM's computing equipment for the business market. The speed with which UNIVAC's magnetic tape could input data was faster than IBM's punch card technology, but it was not until the presidential election of 1952 that the public accepted the UNIVAC's abilities.

UNIVAC SPECS: The UNIVAC had an add time of 120 microseconds, multiply time of 1,800 microseconds and a divide time of 3,600 microseconds. Input consisted of magnetic tape with a speed of 12,800 characters per second with a read-in speed of 100 inches per second, records at 20 characters per inch, records at 50 characters per inch, card to tape converter 240 cards per minute, 80 column punched card input 120 characters per inch, and punched paper tape to magnetic tape converter 200 characters a second. Output media/speed was magnetic tape/12,800 characters per second, uniprinter/10-11 characters per second, high speed printer/600 lines per minute, tape to card converter/120 cards per minute, Rad Lab buffer storage/Hg 3,500 microsecond, or 60 words per minute.

In a publicity stunt, the UNIVAC computer was used to predict the results of the Eisenhower-Stevenson presidential race. The computer had correctly predicted that Eisenhower would win, but the news media decided to blackout the computer's prediction and declared that the UNIVAC had been stumped. When the truth was revealed, it was considered amazing that a computer could do what political forecasters could not, and the UNIVAC quickly became a household name. The original UNIVAC now sits in the Smithsonian Institution.