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Programming the ENIAC: an example of why computer history is hard (computerhistory.org)
44 points by ingve on May 20, 2016 | hide | past | web | favorite | 16 comments



Great read.

>no one challenged the status of the stored program as the defining feature of the modern digital electronic computer”, but “we struggle when required to articulate its significance in simple terms"

Are we? Then it's probably because we're being dishonest about using it to keep score of which machine was 'first'. Like the article says : 'first computer', 'first electronic computer', 'first electronic stored program computer'. Throw a handful of 'general purpose' in there and you've got a spectrum of candidates from the old astronomy tools through the difference engine through the Z3 to the Mark I. Honestly, the only time I ever hear or read anyone say 'first stored program...' is as a presage to claiming that the MkI was first so ra ra, we beat the yanks.


> Even before ENIAC was finished, engineers realized that there was a much better centralized way to control such a complex machine, using coded instructions stored in memory and "executed" in sequence.

> For a discussion of how it was different from earlier ideas, see Tom Haigh’s recent article "Where Code Comes From".

This article links to "Where Code Comes From" at CACM, but beyond an excerpt it is members-only. Here's the full article on the author's web site (PDF):

http://www.tomandmaria.com/Tom/Writing/WhereCodeComesFromCAC...


Wow, that looks great. I highly recommend that you submit it as an article in its own right, perhaps tomorrow, so as not to be too close to this thread.


This is such an interesting article to me because it describes a time when a fundamentally unique paradigm of computer science was in it's nascent form. It makes me wonder, were people aware of the watershed nature of their work at the time?

Are there new paradigms being worked on now, that we are aware of, which have a similar significance?

I suppose it may be hard to see such a thing in the moment, but it sure is fun to think about.



This was an interesting read, but I thought the description of the Von Neuman's architectural decision to address program instructions and data in the same address space was a little hasty - perhaps introducing the Harvard architecture or another with separate spaces would help with the argument for ENIAC categorically being a computer.


It's all about memory devices.

IBM had been doing arithmetic electromechanically for decades, and mechanical digital calculators go back centuries. It was clear by the 1940s that you could do arithmetic with vacuum tubes; IBM produced the IBM 603 Electronic Multiplier[1] as a product in 1946, and they'd been working on that before WWII. It was clear that you could have programmed sequence control of arithmetic, if you could figure out how to store and access the program. But nobody had a cheap random-access storage device yet.

There were lots of ideas, most of them marginal. IBM had been using plugboards for decades. Atanasoff used capacitors, but had to use a mechanical drum type rotary switch to connect to them. The ENIAC used tubes, plugboards, and rotary switches. The Manchester Baby used a Williams tube, a CRT-derived storage device, but they only got 32 words of 32 bits out of it. Bigger Williams tube machines were built later, but the size was huge for the data stored. EDVAC used mercury tank delay lines, as did UNIVAC I. Metal delay lines, long metal rods with transducers at each end, were tried. Some low-end computers with drum main memory were built. Of these, only the Williams tube was random access.

In 1951, MIT built Whirlwind, the first computer with magnetic core memory. This was the first good memory component. Good speed, true random access, more compact than the alternatives. But not cheap. Core memory was very expensive to manufacture (a million dolars for a megabyte) until IBM figured out how to build a machine to weave it automatically.[2] Core memory powered most of the machines of the late 1950s, 1960s, and early 1970s, until semiconductor RAM finally worked.

Building early computers wasn't a conceptual problem. Lots of people had workable ideas about how to do it. It wasn't a problem with electronic arithmetic; that had been done. But there were no good memory technologies yet.

It's been mostly forgotten, but in the late 1950s and 1960s, there were a whole range of special purpose machines built which were not general purpose digital computers, but did some specific function with digital electronics. Reservisor did airline reservations. Teleregister had special purpose systems for stockbrokers, airlines, railroad companies, and inventory control.[3] These were all hard-wired and stored most of their data on magnetic drums or plugboards. All this was a workaround for expensive memory. Once memory got cheap, those special purpose machines disappeared.

[1] https://en.wikipedia.org/wiki/IBM_603 [2] http://ibm-1401.info/IBMCoreArraysIEEEMagnetics1969.pdf [3] http://archive.computerhistory.org/resources/text/Teleregist...


To amplify how desperate people were for memory, back before the Whirlwind people came up with 3D core memory they were considering among other things a microwave version of mercury delay lines, running a signal out to western Massachusetts and back. All that and lots more in this gem of a book: http://www.amazon.com/Project-Whirlwind-History-Pioneer-Comp...


> We depend heavily on contemporary written documents; as the ancient Chinese proverb says, “The palest ink is better than the best memory.”

I wonder if that's the best possible approach :) . You see, those documents are written by those unreliable people too...


Sounds more like the problem is a lack of definition of terms.


Well, that, and the definition of terms is necessarily being done by the same people who are trying to answer questions raised after-the-fact.


> “Who invented the computer?” A 20-year-old might say “Steve Jobs."

It may well be a complex question of who invented the computer. But I think it's safe to say that it was certainly not Steve Jobs.


Have you ever seen a young person's reaction to an Apple ][?

They say, "What is this?" as they try touching the screen. The older kids look for the mouse, but can't find it. When you show them a floppy, they are perplexed.


It's also safe to say that no one would give that answer to that question. I mean, I'm sure there are tons of people on the Internet who complain about other people thinking that, I just don't necessarily think those other people actually exist in meaningful numbers.

I've come to a similar opinion about people who see "SJWs" all around them. I see people complain about SJWs all the time, but the complaining seems to be about imaginary people who mainly exist as caricatures in their heads. I live in the Bay Area and I don't think I've seen anything resembling an SJW in the wild, aside from some isolated individual posting angry rants to Tumblr.


In SF I've witnessed, first hand, people accusing others of "cultural appropriation" which is about as silly as you can get. I only visit now and then though, so I don't know if a lot of people are like this or I just had an unlucky experience. But look at Github and their racist and sexist policies disguised under "social justice" (their words). It's safe to assume those people live there and actually believe those things.

Sure though, it might not be "all around them", unless they're at college.


Oh I don't deny any of those incidents or that such people exist and have been responsible for some bad things, but in my experience for every actual SJW stereotype that exists in the world, there are hundreds or thousands of very vocal people who dedicate utterly tremendous amounts of time, energy, and vitriol to public hand-wringing about such people.

Oddly enough, the people who put the most time and energy into publicly venting about racism and sexism practiced in the name of social justice don't seem to spend much of their remaining time fighting against other forms racism and sexism. Oddly enough, by some strange coincidence, the more likely someone is to point their finger at a conspiracy of SJWs for being a meaningful source of racism and sexism in the world, the less that same person seems to be concerned about racism and sexism in other forms.

To me it often comes across as little more than one group of people taking pleasure in hating on another (possibly imaginary) group of people, sort of like football rivalries for people who aren't into sports. Unlike football rivalries, it actually influences how the general population thinks about real world issues, which sucks, because voters need to have as much clarity as possible. Otherwise we end up doing things like naming Donald Trump as one of two options for one of the most powerful and influential political offices in the world.

Sorry HN, I fully deserve and accept downvotes for offtopic political ranting. This has just been a peeve of mine lately.




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