ENIAC

ENIAC was a very big computer. It was the first one of its kind. It used many small parts to work.

These parts helped it do math very fast. It was much faster than old tools.

Six women helped tell the machine what to do. They were the first programmers. This big machine was called a "Giant Brain." It helped the army solve hard problems.

ENIAC was a very special machine. It was the first electronic, general-purpose digital computer. This means it could be programmed to solve many different kinds of math problems.

Two men named John Mauchly and J. Presper Eckert designed it. They wanted a way to do math much faster than old machines. ENIAC was finished in 1945. It was much faster than machines that used moving parts.

The machine was very large and heavy. It used 18,000 vacuum tubes. These are glass tubes that help control electricity. Because there were so many tubes, they broke often. Sometimes the machine did not work for half the time.

Six women were the first programmers. They helped tell the machine how to solve problems. They had to use cables and switches to set up the programs. This work was very hard and took a long time. ENIAC was used by the U.S. Army. It helped them study math for weapons and other tasks. It worked at a place in Maryland until 1955.

ENIAC was a very important machine in history. It was the first electronic, general-purpose digital computer. This means it could be programmed to solve many different kinds of math problems.

Other machines had some of these features, but ENIAC was the first to have them all. It was so fast that the press called it a "Giant Brain." It could work about one thousand times faster than older machines that used moving parts. This speed allowed it to solve many complex numerical problems very quickly.

To work, ENIAC used many different parts to handle math. It was a large, modular machine made of many individual panels.

Twenty of these modules were called accumulators. These parts could add or subtract and hold a ten-digit number in memory. Numbers moved between these units across paths called buses. To stay fast, the machine sent and received numbers without using any moving parts. It could even change what it was doing based on the result of a math problem.

Two men named John Mauchly and J. Presper Eckert designed the computer. Mauchly wanted to see if electronics could make math faster. He teamed up with Eckert, who was an expert in electronics. The U.S. Army helped pay for the project. They wanted a machine to help calculate artillery firing tables. Construction began in secret at the University of Pennsylvania under the name "Project PX."

ENIAC was a huge machine with many parts. It contained 18,000 vacuum tubes and about 5,000,000 hand-soldered joints.

The machine weighed more than 30 tons and was very large. It cost about $487,000 to build. Because it used so many vacuum tubes, they broke often. Sometimes the machine was not working for half the time. Engineers worked hard to fix it, eventually reaching a point where a tube failed only every two days.

Programming the machine was a very big job. Instead of typing on a keyboard, people used plugboard wiring and switches.

Six women were the main programmers: Jean Jennings, Marlyn Wescoff, Ruth Lichterman, Betty Snyder, Frances Bilas, and Kay McNulty. They had to map out math problems on paper first. Then, they spent days setting up cables and switches. These women were very smart and understood how the machine worked inside and out.

The Electronic Numerical Integrator and Computer, known as ENIAC, was a groundbreaking machine in the history of technology. Completed in 1945, it was the first programmable, electronic, general-purpose digital computer. While other machines previously held some individual features, ENIAC was the first to combine all these capabilities into one system. It was Turing-complete, which means it could solve a wide variety of numerical problems by being reprogrammed.

This versatility made it a vital tool for complex mathematics. The press even gave it the nickname "Giant Brain" due to its impressive capabilities.

To understand how ENIAC worked, one must look at its modular design. The machine was composed of many individual panels that performed specific mathematical functions.

Twenty of these modules were accumulators, which could add, subtract, and store ten-digit decimal numbers in memory. These units communicated by passing numbers across general-purpose buses, also called trays. To maintain high speeds, the system relied on electronic signals rather than moving mechanical parts. A key feature was its ability to "branch," meaning the machine could trigger different operations depending on the sign of a calculated result.

ENIAC was built from a massive collection of electronic components. It contained 18,000 vacuum tubes, 7,200 crystal diodes, and 6,000 relays. The machine also utilized 70,000 resistors, 10,000 capacitors, and approximately 5,000,000 hand-soldered joints. Because it lacked an internal memory system at its inception, it used IBM punch cards for external memory storage. In 1953, a 100-word magnetic-core memory from the Burroughs Corporation was eventually added to improve its functions. The sheer scale of the machine was immense, weighing over 30 tons and consuming 150 kW of electricity.

Mathematics within the machine was performed through electronic pulses. The accumulators used ten-position ring counters to store digits, where each digit required 36 vacuum tubes. Arithmetic was achieved by "counting" these pulses; if a counter wrapped around, it generated a carry pulse. This process electronically emulated the way the wheels in a mechanical adding machine would turn. The machine was incredibly fast for its time, performing 5,000 simple addition or subtraction operations per second.

It could also perform up to 385 multiplications per second using a special multiplier unit.

The development of ENIAC began in June 1941 under the supervision of John Mauchly. Mauchly wondered if electronics could accelerate mathematical calculations used by the Army Ordnance Department. He partnered with J. Presper Eckert, an electronics expert, to design a high-speed machine. The project was funded by the U.S. Army and conducted in secret at the University of Pennsylvania under the code name "Project PX." Construction began in June 1944, and the machine was completed in May 1945. The total cost of the project was approximately $487,000.

Reliability was a significant challenge during the machine's operation. Because it used so many vacuum tubes, several tubes burned out almost every day. This meant ENIAC was often nonfunctional for about half of its operating time. Most failures occurred during the warm-up and cool-down periods due to thermal stress on the components. Engineers eventually improved this, reaching a rate of one tube failure every two days. In 1954, the machine achieved its longest continuous run of 116 hours without a failure.

Programming ENIAC was a complex and manual process. Unlike modern computers that use stored programs, ENIAC required programmers to set up instructions using plugboard wiring and function tables.

Six female mathematicians—Jean Jennings, Marlyn Wescoff, Ruth Lichterman, Betty Snyder, Frances Bilas, and Kay McNulty—handled the bulk of the programming. They had to map out complex sequences, including loops and subroutines, on paper before setting them into the machine. This physical setup could take several days, followed by intense periods of debugging. These women developed such a deep understanding of the hardware that they could often identify a single failed tube just by analyzing the errors.