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What's worked in Computer Science: 1999 vs. 2015 (2015)

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Re: What's worked in Computer Science: 1999 vs. 2015 (2015)

#151

Post by trenchgun »

gardenhedge wrote: post #132
ildjarn wrote: post #118

Earlier quoted context omitted.

OOP is about bundling state and behaviour into units that hide their internal mechanisms by some kind of interface. Records can have no state - compared to regular classes - so they are an anti-OOP feature.

I would say OOP revolves around the concept of modeling real-world entities or concepts as objects in code. Records encapsulate data fields within an object, providing a way to model real-world entities.

Records existed before and influenced OOP, and they exist outside of OOP today, in imperative and pure functional languages: https://en.wikipedia.org/wiki/Record_%28computer_science%29

Summary by Wikipedia is pretty good:

>Object-oriented programming (OOP) is a programming paradigm based on the concept of objects,[1] which can contain data and code: data in the form of fields (often known as attributes or properties), and code in the form of procedures (often known as methods). In OOP, computer programs are designed by making them out of objects that interact with one another.

But also, from same wikipedia page:

>Attempts to find a consensus definition or theory behind objects have not proven very successful (however, see Abadi & Cardelli, A Theory of Objects[68] for formal definitions of many OOP concepts and constructs), and often diverge widely. For example, some definitions focus on mental activities, and some on program structuring.

https://en.wikipedia.org/wiki/Object-oriented_programming

But I also recommend reading the chapter on objects from "Programming Languages: Application and Interpretation" by Shriram Krishnamurthi. https://www.plai.org/3/2/PLAI%20Version%203.2.2%20electronic...

One sentence summary there is: "Objects — the bundling of data with operations over them — are a generalization of closures."

Re: What's worked in Computer Science: 1999 vs. 2015 (2015)

#152

Post by [deleted] »

ska wrote: post #55
Calavar wrote: post #50

Earlier quoted context omitted.

I'd say 2005 to 2010 is probably more probably more appropriate for not really. By 2015, neural networks were already a really hot research topic. Just off the top of my head, the seq2seq paper was published in 2014 and U-Net and ResNet were published in 2015.

This is eliding most of the history of neural networks as a hot reasearch topics. Since the late 50's early 1960s they've had several resurgences in interest, e.g. 80s RNNs, 90s stuff around several centers. Hell people were doing interesting things with them commercially in the 90's. The late 90s and early 00's had a lot of other interest (kernel methods, SVMs) but NN folks kept plugging, and the hardware to hit the…

[deleted]

Re: What's worked in Computer Science: 1999 vs. 2015 (2015)

#153

Post by simne »

simne wrote: post #106
stevefan1999 wrote: post #14

I would like to suggest that the classical taxonomy of RISC/CISC dichotomy is basically non-existent nowadays -- namely because both sides have influenced each other. It is well known that CISC has taken a lot of inspirations from RISC designs (such as having a lot more registers in x64), and RISC designs also taken some inspirations from CISC (such as having SIMD/vectorization units). In other words, the line betwee…

> classical taxonomy of RISC/CISC dichotomy is basically non-existent nowadays After digest information about IBM 360, I decided, we lost CISCs. One of most important feature of 360 was customizable microcode, which you could load on system boot and got effectively different hardware (like with FPGA emulators of Amiga's). It was widely used to emulate old hardware, like IBM 1401 or IBM 7xxx series. But I have not see…

Did you know for what purposes (targets) made mini-computers and why they was limited?

When computers first appeared, they was big, just because technology limitations made small machines very expensive to use, so scale used to make computations cheaper.

In early 1970s, technology advanced to stage, where become possible to make simplified versions of big computers for some limited tasks, still too expensive for wide use.

Simple illustration, IBM-3033 mainframe with 16MBytes RAM could serve 17500 3270 terminals, and PDP of same time could about few tens (may be 50, I don't know exactly), so mainframes even when was very expensive, but given good cost per workplace.

Known example, PDP used to control one of scientific nuclear reactor. PDP chosen, not because it have best mips/price ratio, but because it was cheapest adequate machine for this task, so is affordable for limited budget.

Very long time, mini machines stay in niche of limited machines, used to avoid much more expensive full-scale mainframes. They used to control industrial automation (CNC), chemical factories and other small things.

Once appeared microcomputers (CPU on one chip), first known on wide market in 1977, they begin eat mini's space from bottom, when mainframes continue to become more cost effective (more terminals with appearance of cheap modems, etc) and eat mini's space from top.

And in 1990s, when appeared affordable 32-bit microprocessors and became affordable Megabytes of RAM, mini's disappear, because their place was captured by micro's.

To be honest, I just don't know anything we could not name microcomputer now, as even IBM Z mainframes are now have single-chip processor and largest supercomputers are practically clouds of SOCs (NUMA architecture).

And I must admit, I still see PDP's (or VAX's) on enterprises, where they still control old machines from 1990s (they are very reliable even when limited from modern view, but still work).

As I remember, last symmetrical multiprocessor supercomputer was Cray Y-MP, later machines become ccNUMA or just NUMA or even cloud.

https://en.wikipedia.org/wiki/LINPACK

Unix was simplified version of Multics, system considered to run on mainframes (BTW even exists officially certified Posix Unix for mainframes).

You could try mainframes software yourself, it is very affordable now with emulator (sure, be careful about license):

https://en.wikipedia.org/wiki/Hercules_(emulator)

And you will see yourself, how many things borrowed by modern OS's from mainframes.

This is nature, people choose simpler, cheaper thing (yes, I don't like x86, my love is 68k).

Re: What's worked in Computer Science: 1999 vs. 2015 (2015)

#154

Post by fulafel »

stevefan1999 wrote: post #14

I would like to suggest that the classical taxonomy of RISC/CISC dichotomy is basically non-existent nowadays -- namely because both sides have influenced each other. It is well known that CISC has taken a lot of inspirations from RISC designs (such as having a lot more registers in x64), and RISC designs also taken some inspirations from CISC (such as having SIMD/vectorization units). In other words, the line betwee…

I don't know if a reduced instruction set can "take inspiration" from a big one, it just becomes a non reduced one.

Also these examples don't feel right for me: x64 has the same number of registers as CISCs traditionally did (eg m68k, z/architecture, vax). 32-bit x86 was just an exceptionally register-starved CISC. And SIMD postdates RISC vs CISC divide for a long time, both schools of architecture got SIMD around the same time.

But the divide has become less relevant because originally instruction set affected chip area a lot, and there were big gains to be had by the quantitative approach of benchmarking compiled apps with different proposed instruction sets and seeing what runs fastest when transistors are spent on hot instructions vs execution engine resources. Nowadays we have more transistors than we know what to do with, and just put in lots of cores that end up sitting idle because of diminishing returns trying to speed up cores with more transistors.

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