Saturday 18 November 2006

Pic of the day: The problem was that the central processing unit grew hotter and hotter for each year.

Dual-core processors

At work this week we got a catalog which included some quite affordable machines with dual-core processors. I have heard about this invention before (I am after all the resident computer guru, by their standards) but I had not expected them to become affordable so quickly. No, I am not going to write about work. But seeing as Windows Vista is coming in January, I want to secure for myself a computer or two with the newest processor type but with Windows XP, while this rare overlap still exists.

Nothing I have heard about Windows Vista indicates that it will be an improvement for me. It requires more processing power, more memory and more hard disk space. It offers a prettier interface and supposedly better security. But I already have Norton security, which I trust more based on the history of the two of them. And I don't spend time looking at my pretty Windows interface... if I use it, it is for some other purpose which keeps my attention. I am pretty sure I could already get my windows to zoom in and out in a cinematic style in XP, but I just want to get to what I'm trying to do. Operating systems should be like good secretaries: You forget they are there and take all the credit yourself... (Until they quit on you.)

***

Ten years ago, when computing magazines and popular science magazines in general wrote about today, it was widely thought that some advance in materials would keep the speed growing, perhaps Germanium or some such instead of silicon, until radically new technologies were ready to take over: Optical computing, quantum computing and perhaps DNA computing. All these are still being experimented on, but the interim solution proved more prosaic. Instead of having one central processing unit running faster and faster, we now have two splitting the work between them.

You may argue that if this is a useful way of doing it, why haven't we done so for a long time already? Wouldn't anybody want a computer with two CPUs, or three or four? The truth is that we HAVE done this for years already, but mostly in servers. For this to work, the programs have to be able to execute more than one "thread" of program code at the same time. Such multithreading already existed in Windows NT: I remember reading an early glowing review about how you could move the mouse pointer before the hourglass had stopped. This was a revolution for MS Windows, although I am pretty sure Unix and the more expensive operating systems had already had it for years if not decades.

For the longest time, multithreading was mainly used with one processor dividing its time between the different threads. This may seem wasteful, but it encourages good programming. The real tasks a modern computer faces involves doing different things at the same time. An operating system such as Windows, for instance, must be able to handle completely different programs running at the same time, and many of those programs again have different things going on: A text processor constantly looks for new input, even while formatting text or autosaving it every 10 minutes, for instance.

But it was in servers that actually using two (or more) processors first became popular, at least in the Windows world. The NT version for servers definitely had support for this before the turn of the century, possibly from its very start. Windows XP has this support built in as well (it is based on the heritage from Windows NT), but there just wasn't much demand for it. The complexity of it, and the fact that the rest of the machine would probably not be able to keep up, made it less than useful for the common user. So who died and made the dual-core chip king this year?

***

What happened was heat. As the processors ran faster and faster, they developed more and more heat. At the same time, shrinking the "wires" on the CPU more and more meant that it became more and more sensitive to heat. Now that they are on the scale measured in nanometers, it doesn't take many stray electrons before some error crops up. With two processor cores, you can still have them very small, but you can run them at half the clock frequency, which means much less heat and so less errors. (Actually you have to run a bit more than half speed, because some time is lost in communication between the parts. But pretty close.)

Dual-core processors then can do the same job at a lower clock frequency, and so they draw less power and create less heat. At least that is how I have seen it explained. What is certain is that it works, with most software. Various reviews I have seen have been very positive. For the most part, they work like one faster processor. With some badly written programs they work at half speed. And then in some situations they work better than a single processor: The computer is always responsive, even when it has a heavy job running. And of course there is the small point of less heat and less power consumption, especially noticeable in laptops.

There is one problem, though. It is no longer possible to just take the clock speed and say "this chip is better than that chip". For instance, the Intel chips used in laptops are noticeably faster than the AMD at the same speed, though it varies somewhat with the task. The two use a slightly different system for integrating two processor cores, evidently. It will probably take some time before the new way of ranking CPUs settles in people's minds. Until then, reading reviews becomes a necessity once again. (In all fairness, AMDs processors are correspondingly cheaper.)

***

In the end, what this all means to me is that before the end of December I better secure for myself a new laptop for the next few years. The one I keep at work is growing very slow... it was from the very dawn of Windows XP and has 248KB RAM. The one I have at home runs Ubuntu Linux instead of Windows. It is inherently immune to viruses, so great for putting directly on the Internet, but there are a lot of my favorite programs it doesn't run, including all the games. (It does run OpenOffice, though, the free and slightly better replacement for MS Office. It also comes with Firefox as standard browser and can run Opera if you insist.)

Hopefully you will hear more about this when I actually order it in December, but this is when I started thinking seriously about the new technology that will power it.