What is a computer dedicated to a single function, such as a calculator or computer game?

ENIAC's design and construction was financed by the United States Army, Ordnance Corps, Research and Development Command, led by Major General Gladeon M. Barnes. The total cost was about $487,000, equivalent to $5,940,000 in 2020.[14] The construction contract was signed on June 5, 1943; work on the computer began in secret at the University of Pennsylvania's Moore School of Electrical Engineering[15] the following month, under the code name "Project PX", with John Grist Brainerd as principal investigator. Herman H. Goldstine persuaded the Army to fund the project, which put him in charge to oversee it for them.[16]

ENIAC was designed by John Mauchly and J. Presper Eckert of the University of Pennsylvania, U.S.[17] The team of design engineers assisting the development included Robert F. Shaw (function tables), Jeffrey Chuan Chu (divider/square-rooter), Thomas Kite Sharpless (master programmer), Frank Mural (master programmer), Arthur Burks (multiplier), Harry Huskey (reader/printer) and Jack Davis (accumulators).[18] Significant development work was undertaken by the female mathematicians who handled the bulk of the ENIAC programming: Jean Jennings, Marlyn Wescoff, Ruth Lichterman, Betty Snyder, Frances Bilas, and Kay McNulty.[19] In 1946, the researchers resigned from the University of Pennsylvania and formed the Eckert–Mauchly Computer Corporation.

ENIAC was a large, modular computer, composed of individual panels to perform different functions. Twenty of these modules were accumulators that could not only add and subtract, but hold a ten-digit decimal number in memory. Numbers were passed between these units across several general-purpose buses (or trays, as they were called). In order to achieve its high speed, the panels had to send and receive numbers, compute, save the answer and trigger the next operation, all without any moving parts. Key to its versatility was the ability to branch; it could trigger different operations, depending on the sign of a computed result.

Components

By the end of its operation in 1956, ENIAC contained 18,000 vacuum tubes, 7,200 crystal diodes, 1,500 relays, 70,000 resistors, 10,000 capacitors, and approximately 5,000,000 hand-soldered joints. It weighed more than 30 short tons (27 t), was roughly 8 ft × 3 ft × 100 ft (2 m × 1 m × 30 m) in size, occupied 1,800 sq ft (170 m2) and consumed 150 kW of electricity.[20][21] This power requirement led to the rumor that whenever the computer was switched on, lights in Philadelphia dimmed.[22] Input was possible from an IBM card reader and an IBM card punch was used for output. These cards could be used to produce printed output offline using an IBM accounting machine, such as the IBM 405. While ENIAC had no system to store memory in its inception, these punch cards could be used for external memory storage.[23] In 1953, a 100-word magnetic-core memory built by the Burroughs Corporation was added to ENIAC.[24]

ENIAC used ten-position ring counters to store digits; each digit required 36 vacuum tubes, 10 of which were the dual triodes making up the flip-flops of the ring counter. Arithmetic was performed by "counting" pulses with the ring counters and generating carry pulses if the counter "wrapped around", the idea being to electronically emulate the operation of the digit wheels of a mechanical adding machine.[25]

ENIAC had 20 ten-digit signed accumulators, which used ten's complement representation and could perform 5,000 simple addition or subtraction operations between any of them and a source (e.g., another accumulator or a constant transmitter) per second. It was possible to connect several accumulators to run simultaneously, so the peak speed of operation was potentially much higher, due to parallel operation.[26][27]

It was possible to wire the carry of one accumulator into another accumulator to perform arithmetic with double the precision, but the accumulator carry circuit timing prevented the wiring of three or more for even higher precision. ENIAC used four of the accumulators (controlled by a special multiplier unit) to perform up to 385 multiplication operations per second; five of the accumulators were controlled by a special divider/square-rooter unit to perform up to 40 division operations per second or three square root operations per second.

The other nine units in ENIAC were the initiating unit (started and stopped the machine), the cycling unit (used for synchronizing the other units), the master programmer (controlled loop sequencing), the reader (controlled an IBM punch-card reader), the printer (controlled an IBM card punch), the constant transmitter, and three function tables.[29][30]

Operation times

The references by Rojas and Hashagen (or Wilkes)[17] give more details about the times for operations, which differ somewhat from those stated above.

The basic machine cycle was 200 microseconds (20 cycles of the 100 kHz clock in the cycling unit), or 5,000 cycles per second for operations on the 10-digit numbers. In one of these cycles, ENIAC could write a number to a register, read a number from a register, or add/subtract two numbers.

A multiplication of a 10-digit number by a d-digit number (for d up to 10) took d+4 cycles, so a 10- by 10-digit multiplication took 14 cycles, or 2,800 microseconds—a rate of 357 per second. If one of the numbers had fewer than 10 digits, the operation was faster.

Division and square roots took 13(d+1) cycles, where d is the number of digits in the result (quotient or square root). So a division or square root took up to 143 cycles, or 28,600 microseconds—a rate of 35 per second. (Wilkes 1956:20[17] states that a division with a 10 digit quotient required 6 milliseconds.) If the result had fewer than ten digits, it was obtained faster.

ENIAC is able to process about 500 FLOPS,[31] compared to modern supercomputers' petascale and exascale computing power.

Reliability

ENIAC used common octal-base radio tubes of the day; the decimal accumulators were made of 6SN7 flip-flops, while 6L7s, 6SJ7s, 6SA7s and 6AC7s were used in logic functions.[32] Numerous 6L6s and 6V6s served as line drivers to drive pulses through cables between rack assemblies.

Several tubes burned out almost every day, leaving ENIAC nonfunctional about half the time. Special high-reliability tubes were not available until 1948. Most of these failures, however, occurred during the warm-up and cool-down periods, when the tube heaters and cathodes were under the most thermal stress. Engineers reduced ENIAC's tube failures to the more acceptable rate of one tube every two days. According to an interview in 1989 with Eckert, "We had a tube fail about every two days and we could locate the problem within 15 minutes."[33] In 1954, the longest continuous period of operation without a failure was 116 hours—close to five days.

ENIAC could be programmed to perform complex sequences of operations, including loops, branches, and subroutines. However, instead of the stored-program computers that exist today, ENIAC was just a large collection of arithmetic machines, which originally had programs set up into the machine[34] by a combination of plugboard wiring and three portable function tables (containing 1,200 ten-way switches each).[35] The task of taking a problem and mapping it onto the machine was complex, and usually took weeks. Due to the complexity of mapping programs onto the machine, programs were only changed after huge numbers of tests of the current program.[36] After the program was figured out on paper, the process of getting the program into ENIAC by manipulating its switches and cables could take days. This was followed by a period of verification and debugging, aided by the ability to execute the program step by step. A programming tutorial for the modulo function using an ENIAC simulator gives an impression of what a program on the ENIAC looked like.[37][38]

ENIAC's six primary programmers, Kay McNulty, Betty Jennings, Betty Snyder, Marlyn Wescoff, Fran Bilas and Ruth Lichterman, not only determined how to input ENIAC programs, but also developed an understanding of ENIAC's inner workings.[39][40] The programmers were often able to narrow bugs down to an individual failed tube which could be pointed to for replacement by a technician.[41]

Programmers

Kay McNulty, Betty Jennings, Betty Snyder, Marlyn Meltzer, Fran Bilas, and Ruth Lichterman were the first programmers of the ENIAC. They were not, as computer scientist and historian Kathryn Kleiman was once told, "refrigerator ladies", i.e., models posing in front of the machine for press photography.[42] Nevertheless, some of the women did not receive recognition for their work on the ENIAC in their lifetimes.[19] After the war ended, the women continued to work on the ENIAC. Their expertise made their positions difficult to replace with returning soldiers. The original programmers of the ENIAC were neither recognized for their efforts nor known to the public until the mid-1980s.[43]

These early programmers were drawn from a group of about two hundred women employed as computers at the Moore School of Electrical Engineering at the University of Pennsylvania. The job of computers was to produce the numeric result of mathematical formulas needed for a scientific study, or an engineering project. They usually did so with a mechanical calculator. The women studied the machine's logic, physical structure, operation, and circuitry in order to not only understand the mathematics of computing, but also the machine itself.[19] This was one of the few technical job categories available to women at that time.[44] Betty Holberton (née Snyder) continued on to help write the first generative programming system (SORT/MERGE) and help design the first commercial electronic computers, the UNIVAC and the BINAC, alongside Jean Jennings.[45] McNulty developed the use of subroutines in order to help increase ENIAC's computational capability.[46]

Herman Goldstine selected the programmers, whom he called operators, from the computers who had been calculating ballistics tables with mechanical desk calculators, and a differential analyzer prior to and during the development of ENIAC.[19] Under Herman and Adele Goldstine's direction, the computers studied ENIAC's blueprints and physical structure to determine how to manipulate its switches and cables, as programming languages did not yet exist. Though contemporaries considered programming a clerical task and did not publicly recognize the programmers' effect on the successful operation and announcement of ENIAC,[19] McNulty, Jennings, Snyder, Wescoff, Bilas, and Lichterman have since been recognized for their contributions to computing.[47][48][49] Three of the current (2020) Army supercomputers Jean, Kay, and Betty are named for Jean Bartik (Betty Jennings), Kay McNulty, and Betty Snyder respectively.[50]

The "programmer" and "operator" job titles were not originally considered professions suitable for women. The labor shortage created by World War II helped enable the entry of women into the field.[19] However, the field was not viewed as prestigious, and bringing in women was viewed as a way to free men up for more skilled labor. Essentially, women were seen as meeting a need in a temporary crisis.[19] For example, the National Advisory Committee for Aeronautics said in 1942, "It is felt that enough greater return is obtained by freeing the engineers from calculating detail to overcome any increased expenses in the computers' salaries. The engineers admit themselves that the girl computers do the work more rapidly and accurately than they would. This is due in large measure to the feeling among the engineers that their college and industrial experience is being wasted and thwarted by mere repetitive calculation".[19]

Following the initial six programmers, an expanded team of a hundred scientists was recruited to continue work on the ENIAC. Among these were several women, including Gloria Ruth Gordon.[51] Adele Goldstine wrote the original technical description of the ENIAC.[52]

Role in the hydrogen bomb

Although the Ballistic Research Laboratory was the sponsor of ENIAC, one year into this three-year project John von Neumann, a mathematician working on the hydrogen bomb at Los Alamos National Laboratory, became aware of this computer.[53] Los Alamos subsequently became so involved with ENIAC that the first test problem run consisted of computations for the hydrogen bomb, not artillery tables.[8] The input/output for this test was one million cards.[54]

Role in development of the Monte Carlo methods

See also: History of Monte Carlo method

Related to ENIAC's role in the hydrogen bomb was its role in the Monte Carlo method becoming popular. Scientists involved in the original nuclear bomb development used massive groups of people doing huge numbers of calculations ("computers" in the terminology of the time) to investigate the distance that neutrons would likely travel through various materials. John von Neumann and Stanislaw Ulam realized the speed of ENIAC would allow these calculations to be done much more quickly.[55] The success of this project showed the value of Monte Carlo methods in science.[56]

A press conference was held on February 1, 1946,[19] and the completed machine was announced to the public the evening of February 14, 1946,[57] featuring demonstrations of its capabilities. Elizabeth Snyder and Betty Jean Jennings were responsible for developing the demonstration trajectory program, although Herman and Adele Goldstine took credit for it.[19] The machine was formally dedicated the next day[58] at the University of Pennsylvania. None of the women involved in programming the machine or creating the demonstration were invited to the formal dedication nor to the celebratory dinner held afterwards.[59]

The original contract amount was $61,700; the final cost was almost $500,000 (approximately equivalent to $8,000,000 in 2021). It was formally accepted by the U.S. Army Ordnance Corps in July 1946. ENIAC was shut down on November 9, 1946, for a refurbishment and a memory upgrade, and was transferred to Aberdeen Proving Ground, Maryland in 1947. There, on July 29, 1947, it was turned on and was in continuous operation until 11:45 p.m. on October 2, 1955.[2]

Role in the development of the EDVAC

A few months after ENIAC's unveiling in the summer of 1946, as part of "an extraordinary effort to jump-start research in the field",[60] the Pentagon invited "the top people in electronics and mathematics from the United States and Great Britain"[60] to a series of forty-eight lectures given in Philadelphia, Pennsylvania; all together called The Theory and Techniques for Design of Digital Computers—more often named the Moore School Lectures.[60] Half of these lectures were given by the inventors of ENIAC.[61]

ENIAC was a one-of-a-kind design and was never repeated. The freeze on design in 1943 meant that the computer design would lack some innovations that soon became well-developed, notably the ability to store a program. Eckert and Mauchly started work on a new design, to be later called the EDVAC, which would be both simpler and more powerful. In particular, in 1944 Eckert wrote his description of a memory unit (the mercury delay line) which would hold both the data and the program. John von Neumann, who was consulting for the Moore School on the EDVAC, sat in on the Moore School meetings at which the stored program concept was elaborated. Von Neumann wrote up an incomplete set of notes (First Draft of a Report on the EDVAC) which were intended to be used as an internal memorandum—describing, elaborating, and couching in formal logical language the ideas developed in the meetings. ENIAC administrator and security officer Herman Goldstine distributed copies of this First Draft to a number of government and educational institutions, spurring widespread interest in the construction of a new generation of electronic computing machines, including Electronic Delay Storage Automatic Calculator (EDSAC) at Cambridge University, England and SEAC at the U.S. Bureau of Standards.[62]

Improvements

A number of improvements were made to ENIAC after 1947, including a primitive read-only stored programming mechanism using the function tables as program ROM,[62][63][64] after which programming was done by setting the switches.[65] The idea has been worked out in several variants by Richard Clippinger and his group, on the one hand, and the Goldstines, on the other,[66] and it was included in the ENIAC patent.[67] Clippinger consulted with von Neumann on what instruction set to implement.[62][68][69] Clippinger had thought of a three-address architecture while von Neumann proposed a one-address architecture because it was simpler to implement. Three digits of one accumulator (#6) were used as the program counter, another accumulator (#15) was used as the main accumulator, a third accumulator (#8) was used as the address pointer for reading data from the function tables, and most of the other accumulators (1–5, 7, 9–14, 17–19) were used for data memory.

In March 1948 the converter unit was installed,[70] which made possible programming through the reader from standard IBM cards.[71][72] The "first production run" of the new coding techniques on the Monte Carlo problem followed in April.[70][73] After ENIAC's move to Aberdeen, a register panel for memory was also constructed, but it did not work. A small master control unit to turn the machine on and off was also added.[74]

The programming of the stored program for ENIAC was done by Betty Jennings, Clippinger, Adele Goldstine and others.[75][63][62] It was first demonstrated as a stored-program computer in April 1948,[76] running a program by Adele Goldstine for John von Neumann. This modification reduced the speed of ENIAC by a factor of 6 and eliminated the ability of parallel computation, but as it also reduced the reprogramming time[69][62] to hours instead of days, it was considered well worth the loss of performance. Also analysis had shown that due to differences between the electronic speed of computation and the electromechanical speed of input/output, almost any real-world problem was completely I/O bound, even without making use of the original machine's parallelism. Most computations would still be I/O bound, even after the speed reduction imposed by this modification.

Early in 1952, a high-speed shifter was added, which improved the speed for shifting by a factor of five. In July 1953, a 100-word expansion core memory was added to the system, using binary-coded decimal, excess-3 number representation. To support this expansion memory, ENIAC was equipped with a new Function Table selector, a memory address selector, pulse-shaping circuits, and three new orders were added to the programming mechanism.[62]

Main article: History of computing hardware

Mechanical computing machines have been around since Archimedes' time (see: Antikythera mechanism), but the 1930s and 1940s are considered the beginning of the modern computer era.

ENIAC was, like the IBM Harvard Mark I and the German Z3, able to run an arbitrary sequence of mathematical operations, but did not read them from a tape. Like the British Colossus, it was programmed by plugboard and switches. ENIAC combined full, Turing-complete programmability with electronic speed. The Atanasoff–Berry Computer (ABC), ENIAC, and Colossus all used thermionic valves (vacuum tubes). ENIAC's registers performed decimal arithmetic, rather than binary arithmetic like the Z3, the ABC and Colossus.

Like the Colossus, ENIAC required rewiring to reprogram until April 1948.[77] In June 1948, the Manchester Baby ran its first program and earned the distinction of first electronic stored-program computer.[78][79][80] Though the idea of a stored-program computer with combined memory for program and data was conceived during the development of ENIAC, it was not initially implemented in ENIAC because World War II priorities required the machine to be completed quickly, and ENIAC's 20 storage locations would be too small to hold data and programs.

Public knowledge

The Z3 and Colossus were developed independently of each other, and of the ABC and ENIAC during World War II. Work on the ABC at Iowa State University was stopped in 1942 after John Atanasoff was called to Washington, D.C., to do physics research for the U.S. Navy, and it was subsequently dismantled.[81] The Z3 was destroyed by the Allied bombing raids of Berlin in 1943. As the ten Colossus machines were part of the UK's war effort their existence remained secret until the late 1970s, although knowledge of their capabilities remained among their UK staff and invited Americans. ENIAC, by contrast, was put through its paces for the press in 1946, "and captured the world's imagination". Older histories of computing may therefore not be comprehensive in their coverage and analysis of this period. All but two of the Colossus machines were dismantled in 1945; the remaining two were used to decrypt Soviet messages by GCHQ until the 1960s.[82][83] The public demonstration for ENIAC was developed by Snyder and Jennings who created a demo that would calculate the trajectory of a missile in 15 seconds, a task that would have taken several weeks for a human computer.[46]

Patent

Main article: Honeywell v. Sperry Rand

For a variety of reasons (including Mauchly's June 1941 examination of the Atanasoff–Berry computer, prototyped in 1939 by John Atanasoff and Clifford Berry), U.S. Patent 3,120,606 for ENIAC, applied for in 1947 and granted in 1964, was voided by the 1973 decision of the landmark federal court case Honeywell, Inc. v. Sperry Rand Corp., putting the invention of the electronic digital computer in the public domain and providing legal recognition to Atanasoff as the inventor of the first electronic digital computer.

The main parts were 40 panels and three portable function tables (named A, B, and C). The layout of the panels was (clockwise, starting with the left wall):

• Initiating Unit
• Cycling Unit
• Master Programmer – panel 1 and 2
• Function Table 1 – panel 1 and 2
• Accumulator 1
• Accumulator 2
• Divider and Square Rooter
• Accumulator 3
• Accumulator 4
• Accumulator 5
• Accumulator 6
• Accumulator 7
• Accumulator 8
• Accumulator 9

• Accumulator 10
• High-speed Multiplier – panel 1, 2, and 3
• Accumulator 11
• Accumulator 12
• Accumulator 13
• Accumulator 14

• Accumulator 15
• Accumulator 16
• Accumulator 17
• Accumulator 18
• Function Table 2 – panel 1 and 2
• Function Table 3 – panel 1 and 2
• Accumulator 19
• Accumulator 20
• Constant Transmitter – panel 1, 2, and 3
• Printer – panel 1, 2, and 3

An IBM card reader was attached to Constant Transmitter panel 3 and an IBM card punch was attached to Printer Panel 2. The Portable Function Tables could be connected to Function Table 1, 2, and 3.[84]

Parts on display

Pieces of ENIAC are held by the following institutions:

• The School of Engineering and Applied Science at the University of Pennsylvania has four of the original forty panels (Accumulator #18, Constant Transmitter Panel 2, Master Programmer Panel 2, and the Cycling Unit) and one of the three function tables (Function Table B) of ENIAC (on loan from the Smithsonian).[84]
• The Smithsonian has five panels (Accumulators 2, 19, and 20; Constant Transmitter panels 1 and 3; Divider and Square Rooter; Function Table 2 panel 1; Function Table 3 panel 2; High-speed Multiplier panels 1 and 2; Printer panel 1; Initiating Unit)[84] in the National Museum of American History in Washington, D.C.[19] (but apparently not currently on display).
• The Science Museum in London has a receiver unit on display.
• The Computer History Museum in Mountain View, California has three panels (Accumulator #12, Function Table 2 panel 2, and Printer Panel 3) and portable function table C on display (on loan from the Smithsonian Institution).[84]
• The University of Michigan in Ann Arbor has four panels (two accumulators, High-speed Multiplier panel 3, and Master Programmer panel 2),[84] salvaged by Arthur Burks.
• The United States Army Ordnance Museum at Aberdeen Proving Ground, Maryland, where ENIAC was used, has Portable Function Table A.
• The U.S. Army Field Artillery Museum in Fort Sill, as of October 2014, obtained seven panels of ENIAC that were previously housed by The Perot Group in Plano, Texas.[85] There are accumulators #7, #8, #11, and #17;[86] panel #1 and #2 that connected to function table #1,[84] and the back of a panel showing its tubes. A module of tubes is also on display.
• The United States Military Academy at West Point, New York, has one of the data entry terminals from the ENIAC.
• The Heinz Nixdorf Museum in Paderborn, Germany, has three panels (Printer panel 2 and High-speed Function Table)[84] (on loan from the Smithsonian Institution). In 2014 the museum decided to rebuild one of the accumulator panels – reconstructed part has the look and feel of a simplified counterpart from the original machine.[87][88]

ENIAC was named an IEEE Milestone in 1987.[89]

In 1996, in honor of the ENIAC's 50th anniversary, The University of Pennsylvania sponsored a project named, "ENIAC-on-a-Chip", where a very small silicon computer chip measuring 7.44 mm by 5.29 mm was built with the same functionality as ENIAC. Although this 20 MHz chip was many times faster than ENIAC, it had but a fraction of the speed of its contemporary microprocessors in the late 1990s.[90][91][92]

In 1997, the six women who did most of the programming of ENIAC were inducted into the Technology International Hall of Fame.[47][93] The role of the ENIAC programmers is treated in a 2010 documentary film titled Top Secret Rosies: The Female "Computers" of WWII by LeAnn Erickson.[48] A 2014 documentary short, The Computers by Kate McMahon, tells of the story of the six programmers; this was the result of 20 years' research by Kathryn Kleiman and her team as part of the ENIAC Programmers Project.[49][94]

In 2011, in honor of the 65th anniversary of the ENIAC's unveiling, the city of Philadelphia declared February 15 as ENIAC Day.[95]

The ENIAC celebrated its 70th anniversary on February 15, 2016.[96]

• History of computing
• History of computing hardware
• Women in computing
• List of vacuum-tube computers
• Military computers
• Unisys
• Arthur Burks
• Betty Holberton
• Frances Bilas Spence
• John Mauchly
• J. Presper Eckert
• Jean Jennings Bartik
• Kathleen Antonelli (Kay McNulty)
• Marlyn Meltzer
• Ruth Lichterman Teitelbaum

1. ^ Eckert Jr., John Presper and Mauchly, John W.; Electronic Numerical Integrator and Computer, United States Patent Office, US Patent 3,120,606, filed 1947-06-26, issued 1964-02-04; invalidated 1973-10-19 after court ruling in Honeywell v. Sperry Rand.
2. ^ a b Weik, Martin H. "The ENIAC Story". Ordnance. Washington, DC: American Ordnance Association (January–February 1961). Archived from the original on August 14, 2011. Retrieved March 29, 2015.
3. ^ "3.2 First Generation Electronic Computers (1937-1953)". www.phy.ornl.gov.
4. ^ "ENIAC on Trial – 1. Public Use". www.ushistory.org. Search for 1945. Retrieved May 16, 2018. The ENIAC machine [...] was reduced to practice no later than the date of commencement of the use of the machine for the Los Alamos calculations, December 10, 1945.
5. ^ Goldstine & Goldstine 1946, p. 97
6. ^ Shurkin, Joel (1996). Engines of the mind: the evolution of the computer from mainframes to microprocessors. New York: Norton. ISBN 978-0-393-31471-7.
7. ^ Moye, William T. (January 1996). "ENIAC: The Army-Sponsored Revolution". US Army Research Laboratory. Archived from the original on May 21, 2017. Retrieved March 29, 2015.
8. ^ a b Goldstine 1972, p. 214.
9. ^ Richard Rhodes (1995). "chapter 13". Dark Sun: The Making of the Hydrogen Bomb. p. 251. The first problem assigned to the first working electronic digital computer in the world was the hydrogen bomb. […] The ENIAC ran a first rough version of the thermonuclear calculations for six weeks in December 1945 and January 1946.
10. ^ McCartney 1999, p. 103: "ENIAC correctly showed that Teller's scheme would not work, but the results led Teller and Ulam to come up with another design together."
11. ^ *"ENIAC on Trial – 1. Public Use". www.ushistory.org. Search for 1945. Retrieved May 16, 2018. The ENIAC machine […] was reduced to practice no later than the date of commencement of the use of the machine for the Los Alamos calculations, December 10, 1945.
12. ^ Brain used in the press as a metaphor became common during the war years. Looking, for example, at Life magazine: Overseas Air Lines Rely on Magic Brain. August 16, 1937. p. 45. (RCA Radiocompass). the Magic Brain—is a development of RCA engineers. March 9, 1942. p. 55. (RCA Victrola). Blanket with a Brain does the rest!. December 14, 1942. p. 8. (GE Automatic Blanket). Mechanical brain sights gun. November 8, 1943. p. 8. (How to boss a BOFORS!)
13. ^ "ENIAC USA 1946". The History of Computing Project. History of Computing Foundation. March 13, 2013. Archived from the original on January 4, 2021.
14. ^ Dalakov, Georgi. "ENIAC". History of Computers. Georgi Dalakov. Retrieved May 23, 2016.
15. ^ Goldstine & Goldstine 1946
16. ^ Gayle Ronan Sims (June 22, 2004). "Herman Heine Goldstine". Philadelphia Inquirer. Archived from the original on November 30, 2015. Retrieved April 15, 2017 – via www.princeton.edu.
17. ^ a b c Wilkes, M. V. (1956). Automatic Digital Computers. New York: John Wiley & Sons. QA76.W5 1956.
18. ^ "ENIAC on Trial". USHistory.org. Independence Hall Association. Archived from the original on August 12, 2019. Retrieved November 9, 2020.
19. ^ a b c d e f g h i j k Light 1999.
20. ^ "ENIAC". The Free Dictionary. Retrieved March 29, 2015.
21. ^ Weik, Martin H. (December 1955). Ballistic Research Laboratories Report No. 971: A Survey of Domestic Electronic Digital Computing Systems. Aberdeen Proving Ground, MD: United States Department of Commerce Office of Technical Services. p. 41. Retrieved March 29, 2015.
22. ^ Farrington, Gregory (March 1996). ENIAC: Birth of the Information Age. Popular Science. Retrieved March 29, 2015.
23. ^ "ENIAC in Action: What it Was and How it Worked". ENIAC: Celebrating Penn Engineering History. University of Pennsylvania. Retrieved May 17, 2016.
24. ^ Martin, Jason (December 17, 1998). "Past and Future Developments in Memory Design". Past and Future Developments in Memory Design. University of Maryland. Retrieved May 17, 2016.
25. ^ Peddie, Jon (June 13, 2013). The History of Visual Magic in Computers: How Beautiful Images are Made in CAD, 3D, VR and AR. Springer Science & Business Media. ISBN 978-1-4471-4932-3.
26. ^ Goldstine & Goldstine 1946.
27. ^ Igarashi, Yoshihide; Altman, Tom; Funada, Mariko; Kamiyama, Barbara (May 27, 2014). Computing: A Historical and Technical Perspective. CRC Press. ISBN 978-1-4822-2741-3.
28. ^ The original photo can be seen in the article: Rose, Allen (April 1946). "Lightning Strikes Mathematics". Popular Science: 83–86. Retrieved March 29, 2015.
29. ^ Clippinger 1948, Section I: General Description of the ENIAC – The Function Tables.
30. ^ Goldstine 1946.
31. ^ "The incredible evolution of supercomputers' powers, from 1946 to today". Popular Science. March 18, 2019. Retrieved February 8, 2022.
32. ^ Burks 1947, pp. 756–767
33. ^ Randall 5th, Alexander (February 14, 2006). "A lost interview with ENIAC co-inventor J. Presper Eckert". Computer World. Retrieved March 29, 2015.
34. ^ Grier, David (July–September 2004). "From the Editor's Desk". IEEE Annals of the History of Computing. 26 (3): 2–3. doi:10.1109/MAHC.2004.9. S2CID 7822223.
35. ^ Cruz, Frank (November 9, 2013). "Programming the ENIAC". Programming the ENIAC. Columbia University. Retrieved May 16, 2016.
36. ^ Alt, Franz (July 1972). "Archaeology of computers: reminiscences, 1945-1947". Communications of the ACM. 15 (7): 693–694. doi:10.1145/361454.361528. S2CID 28565286.
37. ^ Schapranow, Matthieu-P. (June 1, 2006). "ENIAC tutorial - the modulo function". Archived from the original on January 7, 2014. Retrieved March 4, 2017.
38. ^ Description of Lehmer's program computing the exponent of modulo 2 prime
    • De Mol & Bullynck 2008
39. ^ "ENIAC Programmers Project". eniacprogrammers.org. Retrieved March 29, 2015.
40. ^ Donaldson James, Susan (December 4, 2007). "First Computer Programmers Inspire Documentary". ABC News. Retrieved March 29, 2015.
41. ^ Fritz, W. Barkley (1996). "The Women of ENIAC" (PDF). IEEE Annals of the History of Computing. 18 (3): 13–28. doi:10.1109/85.511940. Archived from the original (PDF) on March 4, 2016. Retrieved April 12, 2015.
42. ^ "Meet the 'Refrigerator Ladies' Who Programmed the ENIAC". Mental Floss. October 13, 2013. Retrieved June 16, 2016.
43. ^ "ENIAC Programmers: A History of Women in Computing". Atomic Spin. July 31, 2016.
44. ^ Grier, David (2007). When Computers Were Human. Princeton University Press. ISBN 9781400849369. Retrieved November 24, 2016.
45. ^ Beyer, Kurt (2012). Grace Hopper and the Invention of the Information Age. London, Cambridge: MIT Press. p. 198. ISBN 9780262517263.
46. ^ a b Isaacson, Walter (September 18, 2014). "Walter Isaacson on the Women of ENIAC". Fortune. Archived from the original on December 12, 2018. Retrieved December 14, 2018.
47. ^ a b "Invisible Computers: The Untold Story of the ENIAC Programmers". Witi.com. Retrieved March 10, 2015.
48. ^ a b Gumbrecht, Jamie (February 2011). "Rediscovering WWII's female 'computers'". CNN. Retrieved February 15, 2011.
49. ^ a b "Festival 2014: The Computers". SIFF. Archived from the original on August 10, 2014. Retrieved March 12, 2015.
50. ^ "Army researchers acquire two new supercomputers". U.S. Army DEVCOM Army Research Laboratory Public Affairs. December 28, 2020. Retrieved March 1, 2021.
51. ^ Sullivan, Patricia (July 26, 2009). "Gloria Gordon Bolotsky, 87; Programmer Worked on Historic ENIAC Computer". The Washington Post. Retrieved August 19, 2015.
52. ^ "ARL Computing History | U.S. Army Research Laboratory". Arl.army.mil. Retrieved June 29, 2019.
53. ^ Goldstine 1972, p. 182
54. ^ Goldstine 1972, p. 226
55. ^ Mazhdrakov, Metodi; Benov, Dobriyan; Valkanov, Nikolai (2018). The Monte Carlo Method. Engineering Applications. ACMO Academic Press. p. 250. ISBN 978-619-90684-3-4.
56. ^ Kean, Sam (2010). The Disappearing Spoon. New York: Little, Brown and Company. pp. 109–111. ISBN 978-0-316-05163-7.
57. ^ Kennedy, Jr., T. R. (February 15, 1946). "Electronic Computer Flashes Answers". New York Times. Archived from the original on July 10, 2015. Retrieved March 29, 2015.
58. ^ Honeywell, Inc. v. Sperry Rand Corp., 180 U.S.P.Q. (BNA) 673, p. 20, finding 1.1.3 (U.S. District Court for the District of Minnesota, Fourth Division 1973) ("The ENIAC machine which embodied 'the invention' claimed by the ENIAC patent was in public use and non-experimental use for the following purposes, and at times prior to the critical date: ... Formal dedication use February 15, 1946 ...").
59. ^ Evans, Claire L. (March 6, 2018). Broad Band: The Untold Story of the Women Who Made the Internet. Penguin. p. 51. ISBN 9780735211766.
60. ^ a b c McCartney 1999, p. 140
61. ^ McCartney 1999, p. 140: "Eckert gave eleven lectures, Mauchly gave six, Goldstine gave six. von Neumann, who was to give one lecture, didn't show up; the other 24 were spread among various invited academics and military officials."
62. ^ a b c d e f "Eniac". Epic Technology for Great Justice. Retrieved January 28, 2017.
63. ^ a b Goldstine 1947.
64. ^
    • Goldstine 1972, pp. 233–234, 270, search string: "eniac Adele 1947"
    By July 1947 von Neumann was writing: "I am much obliged to Adele for her letters. Nick and I are working with her new code, and it seems excellent."
    • Clippinger 1948, Section IV: Summary of Orders
    • Haigh, Priestley & Rope 2014b, pp. 44–48
65. ^ Pugh, Emerson W. (1995). "Notes to Pages 132-135". Building IBM: Shaping an Industry and Its Technology. MIT Press. p. 353. ISBN 9780262161473.
66. ^ Haigh, Priestley & Rope 2014b, pp. 44–45.
67. ^ Haigh, Priestley & Rope 2014b, p. 44.
68. ^ Clippinger 1948, INTRODUCTION.
69. ^ a b Goldstine 1972, 233-234, 270; search string: eniac Adele 1947.
70. ^ a b Haigh, Priestley & Rope 2014b, pp. 47–48.
71. ^ Clippinger 1948, Section VIII: Modified ENIAC.
72. ^ Fritz, W. Barkley (1949). "Description and Use of the ENIAC Converter Code". Technical Note (141). Section 1. – Introduction, p. 1. At present it is controlled by a code which incorporates a unit called the Converter as a basic part of its operation, hence the name ENIAC Converter Code. These code digits are brought into the machine either through the Reader from standard IBM cards*or from the Function Tables (...). (...) *The card control method of operation is used primarily for testing and the running of short highly iterative problems and is not discussed in this report.
73. ^ Haigh, Thomas; Priestley, Mark; Rope, Crispin (July–September 2014c). "Los Alamos Bets On ENIAC: Nuclear Monte Carlo Simulations 1947-48". IEEE Annals of the History of Computing. 36 (3): 42–63. doi:10.1109/MAHC.2014.40. S2CID 17470931. Retrieved November 13, 2018.
74. ^ Haigh, Priestley & Rope 2016, pp. 113–114.
75. ^ Clippinger 1948, INTRODUCTION
    • Full names: Haigh, Priestley & Rope 2014b, p. 44
76. ^ Haigh, Priestley & Rope 2016, p. 153.
77. ^ See #Improvements
78. ^ "Programming the ENIAC: an example of why computer history is hard | @CHM Blog". Computer History Museum. May 18, 2016.
79. ^ Haigh, Thomas; Priestley, Mark; Rope, Crispin (January–March 2014a). "Reconsidering the Stored Program Concept". IEEE Annals of the History of Computing. 36 (1): 9–10. doi:10.1109/mahc.2013.56. S2CID 18827916.
80. ^ Haigh, Priestley & Rope 2014b, pp. 48–54.
81. ^ Copeland 2006, p. 106.
82. ^ Copeland 2006, p. 2.
83. ^ Ward, Mark (May 5, 2014), "How GCHQ built on a colossal secret", BBC News
84. ^ a b c d e f g Haigh, Priestley & Rope 2016, pp. 46, 264.
85. ^ Meador, Mitch (October 29, 2014). "ENIAC: First Generation Of Computation Should Be A Big Attraction At Sill". The Lawton Constitution. Retrieved April 8, 2015.
86. ^ Haigh. et al. list accumulators 7, 8, 13, and 17, but 2018 photos show 7, 8, 11, and 17.[full citation needed]
87. ^ "Meet the iPhone's 30-ton ancestor: Inside the project to rebuild one of the first computers". TechRepublic. November 23, 2016. Bringing the Eniac back to life.
88. ^ "ENIAC – Life-size model of the first vacuum-tube computer". Germany: Heinz Nixdorf Museum. Retrieved March 1, 2021.
89. ^ "Milestones:Electronic Numerical Integrator and Computer, 1946". IEEE Global History Network. IEEE. Retrieved August 3, 2011.
90. ^ "Looking Back At ENIAC: Commemorating A Half-Century Of Computers In The Reviewing System". The Scientist Magazine.
91. ^ Van Der Spiegel, Jan (1996). "ENIAC-on-a-Chip". PENN PRINTOUT. Vol. 12, no. 4. The University of Pennsylvania. Archived from the original on October 11, 2012. Retrieved October 17, 2016.
92. ^ Van Der Spiegel, Jan (May 9, 1995). "ENIAC-on-a-Chip". University of Pennsylvania. Retrieved September 4, 2009.
93. ^ Brown, Janelle (May 8, 1997). "Wired: Women Proto-Programmers Get Their Just Reward". Retrieved March 10, 2015.
94. ^ "ENIAC Programmers Project". ENIAC Programmers Project. Retrieved November 25, 2021.
95. ^ "Resolution No. 110062: Declaring February 15 as "Electronic Numerical Integrator And Computer (ENIAC) Day" in Philadelphia and honoring the University of Pennsylvania School of Engineering and Applied Sciences" (PDF). February 10, 2011. Retrieved August 13, 2014.
96. ^ Kim, Meeri (February 11, 2016). "70 years ago, six Philly women became the world's first digital computer programmers". Retrieved October 17, 2016 – via www.phillyvoice.com.

• Burks, Arthur (1947). "Electronic Computing Circuits of the ENIAC". Proceedings of the I.R.E. 35 (8): 756–767. doi:10.1109/jrproc.1947.234265.
• Burks, Arthur; Burks, Alice R. (1981). "The ENIAC: The First General-Purpose Electronic Computer". Annals of the History of Computing. 3 (4): 310–389. doi:10.1109/mahc.1981.10043. S2CID 14205498.
• Clippinger, R. F. (September 29, 1948). Source. "A Logical Coding System Applied to the ENIAC". Ballistic Research Laboratories Report (673). Archived from the original on January 3, 2010. Retrieved January 27, 2010. {{cite journal}}: External link in |others= (help)
• Copeland, B. Jack, ed. (2006), Colossus: The Secrets of Bletchley Park's Codebreaking Computers, Oxford: Oxford University Press, ISBN 978-0-19-284055-4
• De Mol, Liesbeth; Bullynck, Maarten (2008). "A Week-End Off: The First Extensive Number-Theoretical Computation on ENIAC". In Beckmann, Arnold; Dimitracopoulos, Costas; Löwe, Benedikt (eds.). Logic and Theory of Algorithms: 4th Conference on Computability in Europe, CiE 2008 Athens, Greece, June 15-20, 2008, Proceedings. Springer Science & Business Media. pp. 158–167. ISBN 9783540694052.
• Eckert, J. Presper, The ENIAC (in Nicholas Metropolis, J. Howlett, Gian-Carlo Rota, (editors), A History of Computing in the Twentieth Century, Academic Press, New York, 1980, pp. 525–540)
• Eckert, J. Presper and John Mauchly, 1946, Outline of plans for development of electronic computers, 6 pages. (The founding document in the electronic computer industry.)
• Fritz, W. Barkley, The Women of ENIAC (in IEEE Annals of the History of Computing, Vol. 18, 1996, pp. 13–28)
• Goldstine, Adele (1946). Source. "A Report on the ENIAC". FTP.arl.mil. 1 (1). Chapter 1 -- Introduction: 1.1.2. The Units of the ENIAC. {{cite journal}}: External link in |others= (help)
• Goldstine, H. H.; Goldstine, Adele (1946). "The electronic numerical integrator and computer (ENIAC)". Mathematics of Computation. 2 (15): 97–110. doi:10.1090/S0025-5718-1946-0018977-0. ISSN 0025-5718. (also reprinted in The Origins of Digital Computers: Selected Papers, Springer-Verlag, New York, 1982, pp. 359–373)
• Goldstine, Adele K. (July 10, 1947). Central Control for ENIAC. p. 1. Unlike the later 60- and 100-order codes this one [51 order code] required no additions to ENIAC's original hardware. It would have worked more slowly and offered a more restricted range of instructions but the basic structure of accumulators and instructions changed only slightly.
• Goldstine, Herman H. (1972). The Computer: from Pascal to von Neumann. Princeton, NJ: Princeton University Press. ISBN 978-0-691-02367-0.
• Haigh, Thomas; Priestley, Mark; Rope, Crispin (April–June 2014b). "Engineering 'The Miracle of the ENIAC': Implementing the Modern Code Paradigm". IEEE Annals of the History of Computing. 36 (2): 41–59. doi:10.1109/MAHC.2014.15. S2CID 24359462. Retrieved November 13, 2018.
• Haigh, Thomas; Priestley, Mark; Rope, Crispin (2016). ENIAC in Action: Making and Remaking the Modern Computer. MIT Press. ISBN 978-0-262-53517-5.
• Light, Jennifer S. (1999). "When Computers Were Women" (PDF). Technology and Culture. 40 (3): 455–483. doi:10.1353/tech.1999.0128. ISSN 0040-165X. JSTOR 25147356. S2CID 108407884. Retrieved March 9, 2015.
• Mauchly, John, The ENIAC (in Metropolis, Nicholas, Howlett, Jack; Rota, Gian-Carlo. 1980, A History of Computing in the Twentieth Century, Academic Press, New York, ISBN 0-12-491650-3, pp. 541–550, "Original versions of these papers were presented at the International Research Conference on the History of Computing, held at the Los Alamos Scientific Laboratory, 10–15 June 1976.")
• McCartney, Scott (1999). ENIAC: The Triumphs and Tragedies of the World's First Computer. Walker & Co. ISBN 978-0-8027-1348-3.
• Rojas, Raúl; Hashagen, Ulf, editors. The First Computers: History and Architectures, 2000, MIT Press, ISBN 0-262-18197-5
• Stuart, Brian L. (2018). "Simulating the ENIAC [Scanning Our Past]". Proceedings of the IEEE. 106 (4): 761–772. doi:10.1109/JPROC.2018.2813678.
• Stuart, Brian L. (2018). "Programming the ENIAC [Scanning Our Past]". Proceedings of the IEEE. 106 (9): 1760–1770. doi:10.1109/JPROC.2018.2843998.
• Stuart, Brian L. (2018). "Debugging the ENIAC [Scanning Our Past]". Proceedings of the IEEE. 106 (12): 2331–2345. doi:10.1109/JPROC.2018.2878986.

• Berkeley, Edmund. GIANT BRAINS or machines that think. John Wiley & Sons, inc., 1949. Chapter 7 Speed – 5000 Additions a Second: Moore School's ENIAC (Electronic Numerical Integrator And Computer)
• Dyson, George (2012). Turing's Cathedral: The Origins of the Digital Universe. New York: Pantheon Books. ISBN 978-0-375-42277-5.
• Gumbrecht, Jamie (February 8, 2011). "Rediscovering WWII's 'computers'". CNN.com. Retrieved February 9, 2011.
• Hally, Mike. Electronic Brains: Stories from the Dawn of the Computer Age, Joseph Henry Press, 2005. ISBN 0-309-09630-8
• Lukoff, Herman (1979). From Dits to Bits: A personal history of the electronic computer. Portland, OR: Robotics Press. ISBN 978-0-89661-002-6. LCCN 79-90567.
• Tompkins, C. B.; Wakelin, J. H.; High-Speed Computing Devices, McGraw-Hill, 1950.
• Stern, Nancy (1981). From ENIAC to UNIVAC: An Appraisal of the Eckert–Mauchly Computers. Digital Press. ISBN 978-0-932376-14-5.
• "ENIAC Operating Manual" (PDF). www.bitsavers.org.

Wikimedia Commons has media related to ENIAC.

• ENIAC simulation
• Another ENIAC simulation
• Pulse-level ENIAC simulator
• 3D printable model of the ENIAC
• Q&A: A lost interview with ENIAC co-inventor J. Presper Eckert
• Interview with Eckert Transcript of a video interview with Eckert by David Allison for the National Museum of American History, Smithsonian Institution on February 2, 1988. An in-depth, technical discussion on ENIAC, including the thought process behind the design.
• Oral history interview with J. Presper Eckert, Charles Babbage Institute, University of Minnesota. Eckert, a co-inventor of ENIAC, discusses its development at the University of Pennsylvania's Moore School of Electrical Engineering; describes difficulties in securing patent rights for ENIAC and the problems posed by the circulation of John von Neumann's 1945 First Draft of the Report on EDVAC, which placed the ENIAC inventions in the public domain. Interview by Nancy Stern, 28 October 1977.
• Oral history interview with Carl Chambers, Charles Babbage Institute, University of Minnesota. Chambers discusses the initiation and progress of the ENIAC project at the University of Pennsylvania Moore School of Electrical Engineering (1941–46). Oral history interview by Nancy B. Stern, 30 November 1977.
• Oral history interview with Irven A. Travis, Charles Babbage Institute, University of Minnesota. Travis describes the ENIAC project at the University of Pennsylvania (1941–46), the technical and leadership abilities of chief engineer Eckert, the working relations between John Mauchly and Eckert, the disputes over patent rights, and their resignation from the university. Oral history interview by Nancy B. Stern, 21 October 1977.
• Oral history interview with S. Reid Warren, Charles Babbage Institute, University of Minnesota. Warren served as supervisor of the EDVAC project; central to his discussion are J. Presper Eckert and John Mauchly and their disagreements with administrators over patent rights; discusses John von Neumann's 1945 draft report on the EDVAC, and its lack of proper acknowledgment of all the EDVAC contributors.
• ENIAC Programmers Project
• The women of ENIAC
• Programming ENIAC
• How ENIAC took a Square Root
• Mike Muuss: Collected ENIAC documents
• ENIAC chapter in Karl Kempf, Electronic Computers Within The Ordnance Corps, November 1961
• The ENIAC Story, Martin H. Weik, Ordnance Ballistic Research Laboratories, 1961
• ENIAC museum at the University of Pennsylvania
• ENIAC specifications from Ballistic Research Laboratories Report No. 971 December 1955, (A Survey of Domestic Electronic Digital Computing Systems)
• A Computer Is Born, Michael Kanellos, 60th anniversary news story, CNet, February 13, 2006
• 1946 film restored, Computer History Archives Project

Originally released in 1939 it was officially registered in 1941 by RCA and Sylvania as the glass-cased 6SN7GT, originally listed on page 235 of RCA's 1940 RC-14 Receiving Tube Manual, in the Recently Added section, as: 6SN7-GT. Although the 6S-series tubes are often metal-cased, there was never a metal-envelope 6SN7 (there being no pin available to connect the metal shield); there were, however, a few glass-envelope tubes with a metal band, such as the 6SN7A developed during World War II - slightly improved in some respects but the metal band was prone to splitting.[citation needed] Numerous variations on the 6SN7 type have been offered over the years, including:

• 7N7 (Sylvania 1940, short-lived loktal-base version),
• 1633 (RCA 1941, also for 26-V radios),
• 12SX7 (RCA 1946, intended for use in 12-volt aircraft electronics),
• 5692 (RCA 1948, a super-premium version - not exactly identical - with guaranteed 10,000-hour lifetime),
• 6Н8С (Cyrillic, Soviet version, circa 1950, in Latin letters: 6N8S);
• 6SN7 DDR, 6Н8М, E1606 (=CV278), OSW3129 versions with different/larger glass envelopes;
• 6042 (1951, another 1633 type), and
• 6180 (1952)
• 6SN7W (1956; a more rugged military version, glass envelope with metal band)[1]

American military designator for the 6SN7GA is VT-231, and the British called it CV1988. European designations include the 1942 ECC32 (not an exact equivalent), 13D2 and B65.

The 6SN7 has a 6.3 V 600 mA heater/filament. The 12-volt 300 mA filament equivalent is the 12SN7GT or 12SN7GTA. The 14N7 is the Loktal version of the 12SN7GT. There was also a comparatively rare 8V 8SN7 for 450 mA series-string TV sets) and 25 Volt/0.15 Amp heater version: 25SN7GT.

The 1937 6F8G[2] was also an octal-based double triode with essentially the same characteristics as the 6SN7 (or two 6J5's), but in a 'Coke Bottle' large (Outline ST-12) glass envelope with a different pin arrangement and utilising a top cap connection for the first triode's grid (making pin 1 available for a metal shield).

The 6J5, first registered in June 1937,[3] and 6J5GT (registered April 1938; British version L63) were octal single triodes with identical characteristics to one half of a 6SN7. Other equivalents to the 6J5 include:

• VT-94, 6C2, 6J5M, 38565J;
• military versions: CV1933, 10E/11448 and CV1934;
• Loktal base version: 7A4 (military name: CV1770), and
• 12.6 V heater version: 12J5.

They in turn were successors to the 1935 RCA 6C5 and 1938 6P5G.[3]

The 1954 6CG7[4] and 6FQ7 are electrically equivalent to the 6SN7, with nine-pin miniature ("Noval") base (RCA, 1951), also made as an 8.4V 450mA series string heater type as the 8CG7.

In contrast to what some sources claim, the ECC40 with Rimlock base and introduced by Philips in 1948 cannot be considered a successor to the 6SN7[5] as the electrical characteristics are too different.

The 1946 miniature 12AU7/ECC82, with similar, but not identical, electrical characteristics to the 6SN7 and ECC32, and a filament usable on either 6.3V or 12.6V supplies, is more widely used than the 6CG7/6FQ7.

The 6SN7 was used as an audio amplifier in the 1940-1955 period, usually in the driver stages of power amps. The designer of the famous Williamson amplifier, one of the first true high-fidelity designs, suggested use of the 6SN7 (or B65) in his 1949 revision since it is similar to the original circuit's L63 (=6J5) British single triodes, four of which were used in each channel of his 1947 circuit.

The 6SN7 was one of the most important components of the first programmable electronic digital computer, the ENIAC, which contained several thousand of the tubes. The SAGE computer systems used hundreds of 5692s as flip-flops.

With the advent of television, the 6SN7 was well suited for use as a vertical-deflection amplifier. As screen sizes became larger, voltage and power headroom became insufficient. To address this, uprated versions with higher peak voltage and power ratings were introduced. The GE 6SN7GTA (GE, 1950) had anode dissipation uprated to 5.0 watts. The 1954 GE 6SN7GTB also had controlled heater warmup time, better for series heater strings.

The 6SN7 was considered to be obsolete by the 1960s, replaced by the 12AU7, and became almost unobtainable. With the introduction of semiconductor electronics, vacuum tubes of all types ceased to be manufactured by the major producers. A small demand for vacuum tubes in guitar amplifiers and very expensive high-fidelity equipment remained. As existing stocks ran out, factories in eastern Europe and China started to manufacture the 6SN7, and higher-gain 6SL7. As of 2019[update], 6SN7s and 6SL7s are still manufactured in Russia and by JJ Electronic, and are widely available.[6]

• List of vacuum tubes
• 12AT7
• 12AU7
• 12AX7

1. ^ "6SN7W at the National Valve Museum".
2. ^ "6F8G". Retrieved 10 June 2014.
3. ^ a b "6J5". Retrieved 10 June 2014.
4. ^ "6CG7". Retrieved 10 June 2014.
5. ^ "ECC40". Retrieved 10 June 2014.
6. ^ Available to buy

• The Tube Collectors Association
• Datasheet on the 6SN7
• RCA Receiving Tube Manual, RC-14, Harrison NJ, 1940
• RCA receiving Tube Manual, RC-29, harrison NJ, 1973
• Sylvania Technical Manual 14th edition (reprint), 2000
• GE Techni-Talk, Volume 6 number 5, October–November 1954
• Datasheet on the 6CG7
• [1] SPICE MODEL
• Reviews of 6sn7 tubes.