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Eniac, the First General-Purpose Digital Computer, Turns 80

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Re: Eniac, the First General-Purpose Digital Computer, Turns 80

#41

Post by ogogmad »

yaakov34 wrote: post #28
Rochus wrote: post #6

Eniac was indeed impressive and an important milestone. I recommend the 1999 book "ENIAC - The triumphs and tragedies of the world's first computer" by Scott McCartney which is both interesting to read and very informative. Also the review of the book by the late Jean Bartik, one of the "computers" and thus an eyewitnmess, is very interesting: https://web.archive.org/web/20221101120020/https://www.amazo... . Though t…

The Z3 was not a general purpose computer; it was a calculator that performed a predetermined sequence of operations that was written to its tape. It was remarkable for being all-binary in an era when differential gears and cams were very common in computing devices, and had some other advanced features. But the 1990s article that declared it Turing-complete is just silly. It would apply to every four-function calcul…

Would it not have been easy to add branch instructions to it? Just rewind the instruction tape however many places. It seems 99% of the job was done.

Re: Eniac, the First General-Purpose Digital Computer, Turns 80

#43

Post by alephnil »

jcranmer wrote: post #29
Rochus wrote: post #6

Eniac was indeed impressive and an important milestone. I recommend the 1999 book "ENIAC - The triumphs and tragedies of the world's first computer" by Scott McCartney which is both interesting to read and very informative. Also the review of the book by the late Jean Bartik, one of the "computers" and thus an eyewitnmess, is very interesting: https://web.archive.org/web/20221101120020/https://www.amazo... . Though t…

There are three main problems with trying to offer a simple answer to the question of "what is the first computer?" The most obvious of the problems is that a computer isn't a singular technology that springs up de novo, but something that develops from antecedents over a long, messy transition problem that requires a judgement call as to when the proto-computer becomes an actual computer. A judgement call which is o…

In many ways the ENIAC was more like an FPGA than a computer. It was programmed with patch cables connecting the different computational units as well as switches, and had no CPU as such. The cables had to be physically rerouted when changing to a new program, which took weeks. My understanding is that it was eventually programmed to emulate a von Neuman machine around 1948/49. As far as I understand, this was done mainly by Jean Bartik based on Von Neumans ideas.

If this is correct, it was not a von Neuman machine originally, but it eventually became one, and at approximately the same time as the Manchester Baby.

Re: Eniac, the First General-Purpose Digital Computer, Turns 80

#44

Post by rootbear »

adrian_b wrote: post #14
mrob wrote: post #9

Earlier quoted context omitted.

The Z3 was only general purpose by accident, and this was only discovered in 1997 (published 1998). [0] It's only of theoretical interest because the technique required is too inefficient for real-world applications. ENIAC is notable because it was the first intentionally general purpose computer to be built. [0] https://www.inf.fu-berlin.de/inst/ag-ki/rojas_home/documents...

I do not think that it is right at all to say "intentionally general purpose computer". ENIAC was built for a special purpose, the computation of artillery tables. It was a bespoke computer built for a single customer: the United States Army's Ballistic Research Laboratory. This is why it has been designed as the digital electronic equivalent of the analog mechanical computers that were previously used by the Army an…

A counter argument is that Mauchly was actually interesting in using computers for weather modeling and I’m sure that influenced the design of ENIAC. He could only get ENIAC funded if it was valuable to the war effort. I’ve read quite a lot about that machine and I’m not aware of any architectural features that were specific to ballistics calculations. This is unlike the British Colossus, another early computer, which was specifically designed for code breaking and wasn’t general purpose.

As for the objection that it wasn’t stored program, I was interested to learn that it was converted to stored program operation after only two years or so of operation, using the constant table switches as the program store. But the Manchester Baby, which used the same memory for code and data was more significant in the history of stored program machines.

On the general question of “first computer”, I think the answer is whatever machine you want it to be if you heap enough conditional adjectives on it.

Re: Eniac, the First General-Purpose Digital Computer, Turns 80

#47

Post by Rochus »

rootbear wrote: post #44
adrian_b wrote: post #14

Earlier quoted context omitted.

I do not think that it is right at all to say "intentionally general purpose computer". ENIAC was built for a special purpose, the computation of artillery tables. It was a bespoke computer built for a single customer: the United States Army's Ballistic Research Laboratory. This is why it has been designed as the digital electronic equivalent of the analog mechanical computers that were previously used by the Army an…

A counter argument is that Mauchly was actually interesting in using computers for weather modeling and I’m sure that influenced the design of ENIAC. He could only get ENIAC funded if it was valuable to the war effort. I’ve read quite a lot about that machine and I’m not aware of any architectural features that were specific to ballistics calculations. This is unlike the British Colossus, another early computer, whic…

> Mauchly was actually interesting in using computers for weather modeling and I’m sure that influenced the design of ENIAC

True. Mauchly was a physics professor interested in meterology, and he knew that predicting the weather and calculating an artillery shell's flight are mathematically the same type of problem, which was important to get funding. In the fifties, Eniac was even used to calculate weather forecasts (see https://ams.confex.com/ams/2020Annual/webprogram/Manuscript/...). So these were just two related special problems, and it would be a stretch to interpret this as an intention to build a general-purpose computer. The latter had to wait until the sixties.

Re: Eniac, the First General-Purpose Digital Computer, Turns 80

#48

Post by AnimalMuppet »

DaleBiagio wrote: post #36

ENIAC is where the profession of programming was born — and the first programmers were six women: Kay McNulty, Betty Jennings, Betty Snyder, Marlyn Meltzer, Frances Bilas, and Ruth Lichterman. They had to program it by physically rewiring patch cables and flipping switches. There was no programming language, no stored program. The "software" was the hardware configuration itself. It took another decade before FORTRAN…

Even in the 1950s, my mother worked on a machine that could be programmed in octal, but you could change the instruction set with patch cables.

Re: Eniac, the First General-Purpose Digital Computer, Turns 80

#50

Post by jonjacky »

A newer book, from 2016, ENIAC in Action: Making and Remaking the Modern Computer by Thomas Haigh, Mark Priestly, and Crispin Rope

https://mitpress.mit.edu/9780262334433/eniac-in-action/

An interesting revelation here is that, although ENIAC was not originally conceived as a stored program computer, it was quite early converted to one. They repurposed a lookup table intended to calculate functions to store instructions instead. Many of the well-known ENIAC calculations, such as Monte Carlo simulations, were programmed in this mode.

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