The rise of computers dates back to ancient times and to the development of mathematics and calculators. Computers began taking shape in the late 1800s and early 1900s. They were once the size of an entire room and required great amounts of money to fund and purchase. Due to the enormous size and cost of computers, the idea of personal computers did not begin to take shape until the 1960-70s. It is from this point that people started looking into creating more “portable computers” for home use.



The IBM Automatic Sequence Controlled Calculator (ASCC), called the Mark I by Harvard University, was an electro-mechanical computer. The electromechanical ASCC was devised by Howard H. Aiken, an American mathematician, built at IBM and shipped to Harvard in February 1944. It began computations for the U.S. Navy Bureau of Ships in May and was officially presented to the university on August 7, 1944. It was essentially a serial collection of electromechanical calculators and had many similarities to Babbage’s analytical machine. This electronic calculating machine used relays and electromagnetic components to replace mechanical components. MARK-I was capable of performing addition, subtraction, division, multiplication and table reference. However, it was extremely slow, noisy and bulky (approximately 50 ft long, 8 ft high and weighed 5 tons).



The ABC was built by Dr. Atanasoff and graduate student Clifford Berry in the basement of the physics building at Iowa State College during 1939-42. The initial funds were released in September, and the 11-tube prototype was first demonstrated in October, 1939. A December demonstration prompted a grant for construction of the full-scale machine. The ABC was built and tested over the next two years. A January 15, 1941 story in the Des Moines Register announced the ABC as “an electrical computing machine” with more than 300 vacuum tubes that would “compute complicated algebraic equations” (but gave no precise technical description of the computer). The system weighed more than seven hundred pounds (320 kg). It contained approximately 1 mile (1.6 km) of wire, 280 dual-triode vacuum tubes, 31 thyratrons, and was about the size of a desk.

The machine was, however, the first to implement three critical ideas that are still part of every modern computer:

  1. Using binary digits to represent all numbers and data.
  2. Performing all calculations using electronics rather than wheels, ratchets, or mechanical switches.
  3. Organizing a system in which computation and memory are separated.

In addition, the system pioneered the use of regenerative capacitor memory, as in the DRAM still widely used today.

The memory of the Atanasoff-Berry Computer was a pair of drums, each containing 1600 capacitors that rotated on a common shaft once per second. The capacitors on each drum were organized into 32 “bands” of 50 (30 active bands and 2 spares in case a capacitor failed), giving the machine a speed of 30 additions/subtractions per second. Data was represented as 50-bit binary fixed point numbers. The electronics of the memory and arithmetic units could store and operate on 60 such numbers at a time (3000 bits).

The alternating current power line frequency of 60 Hz was the primary clock rate for the lowest level operations. This computer used electronic vacuum tubes and the circuitry was based on George Boole’s Boolean algebra.



Colossus was designed by engineer Tommy Flowers, to solve a problem posed by mathematician Max Newman at the Government Code and Cypher School (GC&CS) at Bletchley Park. The prototype, Colossus Mark 1, was shown to be working in December 1943 and was operational at Bletchley Park by 5 February 1944. Colossus was the world’s first electronic, digital, fixed-program, single-purpose computer with variable coefficients. The Colossus computers were used by British codebreakers during World War II to help in the cryptanalysis of the Lorenz cipher. Without them, the Allies would have been deprived of the very valuable intelligence that was obtained from reading the vast quantity of encrypted high-level telegraphic messages between the German High Command and their army commands throughout occupied Europe. Colossus used thermionic valves (vacuum tubes) to perform Boolean operations and calculations.

Colossus was a special-purpose machine that suited a narrow range of tasks (e.g. it was not capable of performing decimal multiplications). Although colossus was built as a special-purpose computer, it proved flexible enough to be programmed to execute a variety of routines.



ENIAC is an acronym for Electronic Numerical Integrator Analyzer and Computer. It was developed in 1946 by John Eckert and John Mauchly of the Moore School of Engineering at the University of Pennsylvania.

ENIAC, with its 17,468 vacuum tubes, 70,000 resistors, 10,000 capacitors, 1,500 relays, and 6,000 manual switches, was a monument of engineering and an energy hog. The city of Philadelphia reportedly experienced brown-outs when ENIAC drew power at its home at the Moore School of Electrical Engineering at the University of Pennsylvania.

ENIAC was a product of World War II. The military needed to develop firing tables for its artillery, so that gunners in the field could quickly look up which settings to use with a particular weapon on a particular target under particular conditions. The equations to determine these figures were so complex, they took days for a human to calculate; existing mechanical calculators could do slightly better. The Ballistics Research Laboratory (BRL), responsible for providing these figures to soldiers in the field, was falling behind. But BRL heard about the work of John Mauchly at the Moore School. In 1942, he had suggested using vacuum tubes to speed computer calculations.

Lieutenant Herman Goldstine of the BRL followed up on this. Soon BRL commissioned work on a new high-speed computer with Mauchly as chief consultant, his colleague J. Presper Eckert as chief engineer, and Goldstine as liaison. This was in 1943. It took about a year to design ENIAC, and 18 months to build it. By the time it was completed, in November 1945, the war had been over for three months. In a whole second ENIAC could execute 5,000 additions, 357 multiplications, and 38 divisions. This was up to a thousand times faster than its predecessors. A little too late for World War II, ENIAC was kept busy through the Cold War, working on such projects as calculations for the design of a hydrogen bomb.

ENIAC’s main drawback was that programming it was a nightmare. In that sense it was not a general use computer. To change its program meant essentially rewiring it with punch cards and switches in wiring plug boards. It could take a team two days to reprogram the machine.

Despite its flaws, the lessons learned from ENIAC helped computer developers improve the next generation, including EDVAC, UNIVAC, and Whirlwind, all of which improved upon programmability and memory storage. One of ENIAC’s greatest feats was in showing the potential of what could be done.




John Eckert and John Mauchly also proposed the development of Electronic Discrete Variable Automatic Computer (EDVAC). Although, the conceptual design of EDVAC was completed by 1946, it came into existence only in 1949. The EDVAC was the first electronic computer to use the stored program concept introduced by John Von Neumann.

The EDVAC was a binary serial computer with automatic addition, subtraction, multiplication, programmed division and automatic checking with an ultrasonic serial memory capacity of 1,000 44-bit words.

Physically, the computer comprised the following components:

  1. a magnetic tape reader-recorder.
  2. a control unit with an oscilloscope.
  3. a dispatcher unit to receive instructions from the control and memory and direct them to other units.
  4. a computational unit to perform arithmetic operations on a pair of numbers at a time and send the result to memory after checking on a duplicate unit.
  5. a timer.
  6. a dual memory unit consisting of two sets of 64 mercury acoustic delay lines of eight words capacity on each line.
  7. three temporary tanks each holding a single word.

EDVAC’s addition time was 864 microseconds (about 1.16 kHz) and its multiplication time was 2900 microseconds (about 0.38 kHz).

The computer had almost 6,000 vacuum tubes and 12,000 diodes, and consumed 56 kW of power. It covered 45.5 m2 of floor space and weighed 7,850 kg. The full complement of operating personnel was thirty people per eight-hour shift.



The Electronic Delay Storage Automatic Calculator (EDSAC) was also based on John Von Neumann’s stored program concept. The work began on EDSAC in 1946 at Cambridge University by a team headed by Maurice Wilkes. In 1949, the first successful program was run on this machine. It used mercury delay lines for memory and vacuum tubes for logic. EDSAC had 3000 vacuum valves arranged on 12 racks and used tubes filled with mercury for memory. It could carry out only 650 instructions per second. A program was fed into the machine through a sequence of holes punched into a paper tape. The machine occupied a room, which measured 5 meters by 4 meters.



UNIVersal Automatic Computer was the second commercial computer produced in the United States. It was designed principally by J. Presper Eckert and John Mauchly, the inventors of the ENIAC. Design work which began with the company, Eckert-Mauchly Computer Corporation.

UNIVAC I used 5,200 vacuum tubes, weighed 13 metric tons, consumed 125 KW, and could perform about 1,905 operations per second running on a 2.25 MHz clock. The Central Complex alone (i.e. the processor and memory unit) was 4.3 m by 2.4 m by 2.6 m high. The complete system occupied more than 35.5 m2 of floor space.

The main memory consisted of 1000 words of 12 characters. When representing numbers, they were written as 11 decimal digits plus sign. The 1000 words of memory consisted of 100 channels of 10-word mercury delay line registers. The input/output buffers were 60 words each, consisting of 12 channels of 10-word mercury delay line registers. There are six channels of 10-word mercury delay line registers as spares. With modified circuitry, seven more channels control the temperature of the seven mercury tanks, and one more channel is used for the 10 word “Y” register. The total of 126 mercury channels is contained in the seven mercury tanks mounted on the backs of sections MT, MV, MX, NT, NV, NX, and GV. Each mercury tank is divided into 18 mercury channels.

Each 10-word mercury delay line channel is made up of three sections:

  1. A channel in a column of mercury, with receiving and transmitting quartz piezoelectric crystals mounted at opposite ends.
  2. An intermediate frequency chassis, connected to the receiving crystal, containing amplifiers, detector, and compensating delay, mounted on the shell of the mercury tank.
  3. A recirculation chassis, containing cathode follower, pulse former and retimer, modulator, which drives the transmitting crystal, and input, clear, and memory-switch gates, mounted in the sections adjacent to the mercury tanks.



  1. Ada Byron King: Countess of Lovelace and daughter of the British poet, Lord Byron (1815-1852). Ada was a mathematician and wrote extensive notes on Charles Babbage’s calculating machine and suggested how the engine might calculate Bernoulli numbers.
  2. Edith Clarke (1883-1959): At MIT, in June 1919, Clarke received the first Electrical Engineering degree awarded to a woman . She developed and disseminated mathematical methods that simplified calculations and reduced the time spent in solving problems in the design and operation of electrical power systems.
  3. Grace Murray Hopper (1906-1992): Hopper earned an MA in 1930 and a Ph.D. in 1934 in Mathematics from Yale University. She retired from the Navy in 1967 with the rank of Rear Admiral. Hopper created a compiler system that translated mathematical code into machine language. Later versions under her direction, the compiler became the forerunner to modern programming languages. She pioneered the integration of English into programs with the FLOW-MATIC. Hopper received the Computer Sciences “Man of The Year Award” in 1969. She was the first woman to be inducted into the Distinguished Fellow British Computer Society in 1973. The term “bug,” an error or defect in software that causes a program to malfunction originated according to computer folklore when Grace and her team found a dead moth that had been “zapped” by the relay and caused the device to fail.
  4. Erna Hoover: He invented a computerized switching system for telephone traffic. She was awarded the first software patent ever issued (Patent N3,623,007) on Nov. 23, 1971. She was the first female supervisor of a technical department at Bell Labs.
  5. Kay McNulty Mauchly Antonelli and Alice Burks: They made calculations for tables of firing and bombing trajectories, as part of the war effort. This work prompted the development, in 1946, of the ENIAC, the world’s first electronic digital computer.
  6. Adele Goldstine: He assisted in the creation of the ENIAC and wrote the manual to use it.
  7. Joan Margaret Winters: She is a scientific programmer in SLAC Computing Services at the Stanford Linear Accelerator Center, among other achievements.
  8. Alexandra Illmer Forsythe (1918-1980): During the 1960s and 1970s, she co-authored a series of textbooks on computer science. She wrote the first computer science textbook.
  9. Evelyn Boyd Granville: He was one of the first African American women to earn a Ph.D. in Mathematics. During her career, she developed computer programs that were used for trajectory analysis in the Mercury Project (the first U.S. manned mission in space) and in the Apollo Project.



  1. Charles Babbage (1792-1871): Difference Engine, Analytical Engine. Ada Byron, daughter of the poet, Lord Byron, worked with him. His description, in 1837, of the Analytical Engine, a mechanical digital computer anticipated virtually every aspect of present-day computers.
  2. Alan Turing 1912-1954: British Codebreaker. Worked on the Colossus (code breaking machine, precursor to the computer) and the ACE (Automatic Computing Engine). Turing is perhaps best remembered for the concepts of the Turing Test for Artificial Intelligence and the Turing Machine, an abstract model for modeling computer operations. The Turing Test is the “acid test” of true artificial intelligence as defined by the English scientist Alan Turing. In the 1940s, he said “a machine has artificial intelligence when there is no discernible difference between the conversation generated by the machine and that of an intelligent person.”
  3. John V. Atanasoff (1904 – 1995): One of the contenders, along with Konrad Zuse and H. Edward Roberts and others, as the inventor of the first computer. The limited-function vacuum-tube device had limited capabilities and did not have a central. It was not programmable, but could solve differential equations using binary arithmetic.
  4. J. Presper Eckert, Jr. and John W. Mauchly: Completed the first programmed general purpose electronic digital computer in 1946. They drew on Alansoff’s work to create the ENIAC, the Electronic Numerical Integrator and Computer.
  5. Konrad Zuse (1910-1995): German who, during World War II, designed mechanical and electromechanical computers. Zuse’s Z1, his contender for the first freely programmable computer, contained all the basic components of a modern computer (control unit, memory, micro sequences, etc.). Zuse, because of the scarcity of material during World War II, used discarded video film as punch cards. Like a modern computer, it was adaptable for different purposes and used on/off switch relays, a binary system of 1s and Os (on = 1, off = 0). Completed in 1938, it was destroyed in the bombardment of Berlin in WW II, along with the construction plans. In 1986, Zuse reconstructed the Z1.
  6. J. von Neumann (1903-1957): A child prodigy in mathematics, authored landmark paper explaining how programs could be stored as data.
  7. H. Edward Roberts: He developed the MITS Altair 8800 in 1975. The Altair is considered by some to be the first microcomputer (personal computer), The MITS Altair 8800 was based on a 2 MHZ Intel 8080 chip, with 256 bytes, standard RAM. It was developed a year before the first Apple, by Steve Wozniak and Steve Jobs, came out.
  8. Paul Allen and Bill Gates: (then a student at Harvard) wrote a scaled down version of the Basic programming language to run on the Altair, which was the beginning of Microsoft.

Leave a Reply

Your email address will not be published. Required fields are marked *

Advantages of local domestic helper.
Blogarama - Blog Directory