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Where's My 10 Ghz PC?
An anonymous reader writes "Based on decades of growth in CPU speeds, Santa was supposed to drop off my 10 Ghz PC a few weeks back, but all I got was this lousy 2 Ghz dual processor box -- like it's still 2001...oh please! Dr. Dobbs says the free ride is over, and we now have to come up with some concurrency, but all I have is dollars... What gives?"
Moore's "law" has nothing to do with Hz.
From webopedia
(môrz lâ) (n.) The observation made in 1965 by Gordon Moore, co-founder of Intel, that the number of transistors per square inch on integrated circuits had doubled every year since the integrated circuit was invented. Moore predicted that this trend would continue for the foreseeable future.
Moore's law has nothing to do with processor frequency. It says that semi-conductor capacity doubles every 18 monthsm, not frequency. (With the corollary that there is no appreciable change in price). As we all know, semi-conductor capacity is roughly proportional to speed, so saying processor speeds double every 18 months is not quite wrong, just a little inaccurate. On the other hand, saying that we're not seeing 10 ghz processors, so Moore's law is broken is wrong.
To make laws that man cannot, and will not obey, serves to bring all law into contempt.
--E.C. Stanton
No, making it bigger will make it slower. Current digital systems are mostly "clocked" (they don't have to be, but that gets much more complicated), which means that signals have to be able to get from one side of the system to the other within one clock cycle.
This is why your CPU runs at a faster speed than your L2 cache (which is bigger), which runs at a faster speed than your main memory (which is bigger), which runs at a faster speed than memory in the adjacent NUMA-node (which is bigger), which runs faster than the network (which is bigger),...
Note that I'm talking about latency/clock-rate here; you can get arbitrarily high bandwidth in a big system, but there are times when you have to have low latency and there's no substitute for smallness then; light just isn't that fast!
The problem with that is light speed. Transmitting a lightspeed signal across one centimeter takes about 3.3*10^-11 seconds - which sounds like a lot, until you realize that a single CPU cycle now takes about 3.3*10^-10 seconds. And I don't even know if electricity travels at true lightspeed or at something below that.
:) Yes, you could just fill it with cache, but that still won't give you a computer twice as fast for every twice as much cache - MHz has nothing to do with how many transistors you can pile on a chip. (Of course, you could just put a second CPU on the same chip . . .)
Another problem, of course, is heat - if your 1cm^2 CPU outputs 100w of heat, a 10cm^2 CPU is going to dump 1000w of heat. That's a hell of a lot of heat.
A third problem is reliability. Yields are bad enough with the current core sizes, tripling the core sizes will drop yield even further.
And a fourth problem is what exactly to *do* with the extra space.
Breaking Into the Industry - A development log about starting a game studio.
Ah, yes.
/. /.)
f mel.html 9 .html
It seems that we need to review
The Story of Mel.
I'll post it here from several places,
So that the good people of
(and the other people of
Don't wipe out a single server (yeah, right!)
http://www.cs.utah.edu/~elb/folklore/mel.html
http://www.wizzy.com/andyr/Mel.html
http://www.science.uva.nl/~mes/jargon/t/thestoryo
http://www.outpost9.com/reference/jargon/jargon_4
and, of course, many other places.
That was never the limit of copper. It was the limit of voiceband phone lines, which have artificially constrained bandwidth. Since voiceband is now transmitted digitally at 64Kbs, that's the hard theoretical limit, and 56K analog modems are already asymptotically close to that.
If you hook different equipment to the phone wires without the self-imposed bandwidth filters, then it's easy to get higher bandwidth. Ethernet and its predecessors has been pushing megabits or more over twisted pair for decades.
The problem with that is light speed.
.5c to .7c due to capacitive effects -- very much (exactly, actually) the same way a dielectric (like glass or water) slows down light.
Light speed is a big issue, but so is stray capacitence and inductance. A capacitor tends to short out a high frequency signal, and it takes very little capacitence to look like a dead short to a 10 GHz signal. Similarly, the stray inductance of a straight piece of wire has a high reactance at 10 GHz. That's why they run the processor at high speed internally, but have to slow down the signal before sending it out to the real world. If they sent it out over an optical fiber, things would work much better.
And I don't even know if electricity travels at true lightspeed or at something below that.
Under ideal conditions, electric signals can travel at light speed. In real circuits, it is more like
--Tacky the BSEE
Analogue lines aren't like DS-0 lines, which have a seperate control channel, the control is "bit robbed" from the signal. They take out 8kbps for signaling, giving 56k effective for encoding. That's why with ISDN there is talk of B and D channels. For BRI ISDN you get 2 64k (DS-0) B (bearer) channels that actually carry the signal. There is then a 16k D (data) channel that carries the information on how to route the B channels.
That's also why IDSL is 144k. The total bandwidth of an ISDN line is 144k, but 16k is used for circut switching data. DSL is point-to-point, so that's unnecessary and the D channel's bandwidth can be used for signal.
So 56k is as good as it will ever get for single analogue modems. I suppose, in theory, this could be changed in the future, I suppose, but I find that rather unlikely given that any new technology is likely to be digital end to end.