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The UNIVAC I (UNIVersal Automatic Computer I) was the first general-purpose electronic digital computer design for robot business application produced in the United States.[1] It was designed principally by J. Presper Eckert and John Mauchly, the inventors of the ENIAC. Design work was started by their company, Eckert–Mauchly Computer Corporation (EMCC), and was completed after the company had been acquired by Remington Rand (which later became part of Sperry, now Unisys). In the years before successor models of the UNIVAC I appeared, the machine was simply known as "the UNIVAC".[2]
Source: https://en.wikipedia.org/wiki/UNIVAC_I

On June 14, 1951, the U.S. Census Bureau dedicates UNIVAC, the world’s first commercially produced electronic digital computer. UNIVAC, which stood for Universal Automatic Computer, was developed by J. Presper Eckert and John Mauchly, makers of ENIAC, the first general-purpose electronic digital computer. These giant computers, which used thousands of vacuum tubes for computation, were the forerunners of today’s digital computers.
Source: https://www.history.com/this-day-in-history/univac-computer-dedicated

ENIAC Electronic Numerical Integrator and Computer)[1][2] was the first programmable, electronic, general-purpose digital computer.[3] It was Turing-complete, and able to solve "a large class of numerical problems" through reprogramming.[4][5]
Source: https://en.wikipedia.org/wiki/ENIAC

Which one was the first computer? UNIVAC I or ENIAC? It seems like that UNIVAC I was the first commercially produced electronic digital computer and ENIAC was the first prototype or model computer. Could you please help me with it?

In all the quotes above, the words 'electronic digital computer' are used. Why don't they simply say "electronic computer"? Is it because that both UNIVAC I and ENIAC were both using electronic analog and digital circuitry?

The TRADIC Phase One computer has been claimed to be the world's first fully transistorized computer, ahead of the Mailüfterl in Austria or the Harwell CADET in the UK, which were each completed in 1955. In the UK, the Manchester University Transistor Computer demonstrated a working prototype in 1953[9] which incorporated transistors before TRADIC was operational, although that was not a fully transistorized computer because it used vacuum tubes to generate the clock signal. The 30 watts of power for the 1 MHz clock in the TRADIC was also supplied by a vacuum tube supply because no transistors were available that could supply that much power at that frequency. If the TRADIC can be called fully transistorized while incorporating vacuum tubes, then the Manchester University Transistor Computer should also be, in which case that is the first transistorized computer and not the TRADIC. If neither can be called fully transistorized, then the CADET was the first fully transistorised computer in February 1955.
Source: https://en.wikipedia.org/wiki/TRADIC

Can we say that CADET was first fully digital computer using transistors?

Thank you!

Answers and Replies

  • #2
My understanding is that Eniac came before Univac. Univac was the result of the inventors of Eniac trying to commercialize their idea.

when they say, it’s an electronic digital computer this is to distinguish it from electronic analog computers. Electonic analog computers used tubes or transistors too to solve differential equations:


The article explains it better than I could.

A digital computer before Eniac was the Atanasov Berry computer:


Which was used to break the Eniac patents in a battle of royalties between major computer manufacturers citing it as prior art.
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  • #3
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Maybe you're only interested in the USA, but there was also Conrad Zuse in (first) Germany and after WWII, in Switzerland. Contrary to claims about Eniac, I think Zuse actually might have been earlier than any of them, and he made critical design decisions that had great influence later on, such as pipelining.

https://en.citizendium.org/wiki/History_of_computing#1940s:#The first electronic computers
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  • #4
i think Atanasoff‘s work preceded Zuse by a couple of years. However, Zuse’s work was truly fundamental to modern computing especially his floating pt representation.
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  • #5
when they say, it’s an electronic digital computer this is to distinguish it from electronic analog computers. Electonic analog computers used tubes or transistors too to solve differential equations
Thank you.

So, it would be correct to say that ENIAC was first prototype electronic digital computer and UNIVAC I was the first commercially produced electronic digital computer.

I was thinking that analog computers of the past didn't use vacuum tubes or transistors. So, they did use vacuum and/or transistors but didn't employ two discrete binary values of "0" and "1". Their values must have been continuous.

I think it's rather difficult to claim which of the following was the first computer. It would need to be Turning-complete, reliable, and programmable.

The Atanasoff–Berry computer (ABC) was the first automatic electronic digital computer.[1] Limited by the technology of the day, and execution, the device has remained somewhat obscure. The ABC's priority is debated among historians of computer technology, because it was neither programmable, nor Turing-complete,[2] unlike the widely famous ENIAC machine of 1947 in part derived from it.


Atanasoff and Berry's computer work was not widely known until it was rediscovered in the 1960s, amidst patent disputes over the first instance of an electronic computer. At that time ENIAC, that had been created by John Mauchly and J. Presper Eckert,[6] was considered to be the first computer in the modern sense,[citation needed] but in 1973 a U.S. District Court invalidated the ENIAC patent and concluded that the ENIAC inventors had derived the subject matter of the electronic digital computer from Atanasoff. When, in the mid-1970s, the secrecy surrounding the British World War II development of the Colossus computers that pre-dated ENIAC, was lifted[7][8] and Colossus was described at a conference in Los Alamos, New Mexico in June 1976, John Mauchly and Konrad Zuse were reported to have been astonished.[9]
Source: https://en.wikipedia.org/wiki/Atanasoff–Berry_computer

Colossus was a set of computers developed by British codebreakers in the years 1943–1945 to help in the cryptanalysis of the Lorenz cipher. Colossus used thermionic valves (vacuum tubes) to perform Boolean and counting operations. Colossus is thus regarded[3] as the world's first programmable, electronic, digital computer, although it was programmed by switches and plugs and not by a stored program.[4]
Source: https://en.wikipedia.org/wiki/Colossus_computer

Konrad Zuse's Z1 was really impressive though it was a mechanical device. It was privately funded.

The Z1 was a motor-driven mechanical computer designed by Konrad Zuse from 1936 to 1937, which he built in his parents home from 1936 to 1938.[1][2] It was a binary electrically driven mechanical calculator with limited programmability, reading instructions from punched celluloid film.

The Z1 was the first freely programmable computer in the world which used Boolean logic and binary floating-point numbers, however it was unreliable in operation.[3][4] It was completed in 1938 and financed completely from private funds. This computer was destroyed in the bombardment of Berlin in December 1943, during World War II, together with all construction plans.


The Z1 contained almost all the parts of a modern computer, i.e. control unit, memory, micro sequences, floating-point logic and input–output devices. The Z1 was freely programmable via punched tape and a punched tape reader.[6] There was a clear separation between the punched tape reader, the control unit for supervising the whole machine and the execution of the instructions, the arithmetic unit, and the input and output devices. The input tape unit read perforations in 35-millimeter film.[7]

The Z1 was a 22-bit floating-point value adder and subtracter, with some control logic to make it capable of more complex operations such as multiplication (by repeated additions) and division (by repeated subtractions). The Z1's instruction set had nine instructions and it took between one and twenty cycles per instruction.

The Z1 had a 64-word floating-point memory, where each word of memory could be read from – and written to – the control unit. The mechanical memory units were unique in their design and were patented by Konrad Zuse in 1936. The machine was only capable of executing instructions while reading from the punched tape reader, so the program itself was not loaded in its entirety into internal memory in advance.

The input and output were in decimal numbers, with a decimal exponent and the units had special machinery for converting these to and from binary numbers. The input and output instructions would be read or written as floating-point numbers. The program tape was 35 mm film with the instructions encoded in punched holes.
Source: https://en.wikipedia.org/wiki/Z1_(computer)

One can also check https://en.wikipedia.org/wiki/Z3_(computer)
The Z3 was demonstrated in 1998 to be, in principle, Turing-complete.[12] However, because it lacked conditional branching, the Z3 only meets this definition by speculatively computing all possible outcomes of a calculation.
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  • #6
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I was thinking that analog computers of the past didn't use vacuum tubes or transistors. So, they did use vacuum and/or transistors but didn't employ two discrete binary values of "0" and "1". Their values must have been continuous.
Analog computers were quite widely used until the 1970s and later generations used not only transistors but integrated circuits (e.g. op amps).
In fact, they've never fully gone away. Some non-linear phenomena are easier to study on an analog computer than on a digital computer and people still occasionally build "circuit equivalents" to solve complicated problems (typically non-linear differential equations); but of course this is a niche application.
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  • #7
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I was thinking that analog computers of the past didn't use vacuum tubes or transistors. So, they did use vacuum and/or transistors but didn't employ two discrete binary values of "0" and "1". Their values must have been continuous.
I suspect you are talking about General Purpose computers. A slightly old analog computer (about 60 years) is the Norden Computing Bombsight, completely mechanical.


You could also try:

And going back a couple thousand years:

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And of course, we must mention Charles Babbage, who started work on his "difference engine" in 1822. The machine was intended for calculating and printing mathematical tables. According to Wiki, https://en.wikipedia.org/wiki/Charles_Babbage, "while Babbage's machines were mechanical and unwieldy, their basic architecture was similar to a modern computer. The data and program memory were separated, operation was instruction-based, the control unit could make conditional jumps, and the machine had a separate I/O unit."
He did not finish it but a working version has been made at the Science Museum in London.
"Ada Lovelace, who corresponded with Babbage during his development of the Analytical Engine, is credited with developing an algorithm that would enable the Engine to calculate a sequence of Bernoulli numbers." (Wiki). She is often regarded as the first computer programmer.
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  • #11
Thank you!

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