It's all about two words, "copy protection."
Take a look at the following page from MS research on the "Secure PC":
http://research.microsoft.com/crypto/openbox.asp
"Essentially, this would turn the PC into a record player as far as music is concerned, while preserving the other open aspects of the computer. Record companies could release their records in an encrypted, unable to be copied Windows Media Audio format that would only work on the secure version of the Windows Media Player. A similar arrangement could be reached with the movie studios for film distribution..."
"He [Microsoft Research cryptographer Paul England] says an agreement between software and hardware makers is near, and "we should see some hardware for content protection within a year." Microsoft is already shipping a secure version of Windows Media Player. England is pretty sure that it will be cracked eventually, but he says it will do for now. The way to slam the door on the pirates lies in a modification of the hardware, he says. "We must make it immune to a software attack, and close the PC in that way."..."
So the idea is to embed content protection into the PC from the operating system down to the hardware. So how does this relate to USB? Well, there is no copy protection built into the USB specification. But there will be copy protection support built into the 1394 (Fire Wire) standard, as announced by the 1394 Trade Association (of which MS is a member) three weeks ago.
http://www.1394ta.org/Press/2001Press/mar/3.21.a.h tm
"SANTA CLARA, Calif.--(BUSINESS WIRE)--March 21, 2001-- The leaders of the 1394 Trade Association today urged the consumer electronics and computer industries to adopt the comprehensive digital copy protection system known as Digital Transmission Copy Protection, or ``5C,'' developed by leaders of the electronics industry to prevent unauthorized use of copy-protected content..."
Other members of the 1394 Trade Association include Sony, Philips, Intel, Texas Instruments, Panasonic, Canon, Fujitsu, Compaq and many more.
Six days after the announcement of 1394 support of copy protection, Microsoft confirmed that it would not support USB in Windows XP.
http://www.theregister.co.uk/content/2/17919.html
1394 will incorporate support for DTCP copy protection designed by the 5C group (Sony, Intel, Toshiba, Matushita, and Hitachi):
http://www.dtcp.com/spec.html
"To allow for protected transmission of copy-protected material between digital devices like PC's, DVD Players, and Digital TV's, five companies -- Hitachi, Intel, Matsushita (MEI), Sony and Toshiba have prepared the "5C" Digital Transmission Content Protection (DTCP) specification..."
"The DTCP specification defines a cryptographic protocol for protecting audio/video entertainment content from illegal copying, intercepting and tampering as it traverses high performance digital buses, such as the IEEE 1394 standard."
Microsoft is acting in cooperation with content providers (the music, movie, and video game industry) and with hardware makers to produce a totally copy-protected ("secure") PC. That way the movie and music people can get a payment each time you play a file, and MS will also get its cut. It is essential that copy protection be put into the hardware, since otherwise consumers would be tempted to operating systems without copy protection such as Linux. You will get a music file, from say, Sony, with built-in copy protection, over MS.NET (with possible built in copy protection filters) downloaded to your (copy protected) hard drive, played by MS Media Player (with built in copy protection) running on Windows XP (with copy protection support) and transmitted via the copy protected 1394 bus. It's multi-layered protection and the bus is the last line of defense.
So USB (no built-in copy protection) has to go, and 1394, with built-in copy protection support, gets Windows support from now on.
My analysis would be naive if I were talking about the heatsink. But read the web page that started the discussion. They didn't measure the flatness of the HEAT SINK. They measured the flatness of the PROCESSOR HEAT SPREADER. It's an entirely different object.
The HEAT SINK is a bulky piece of aluminum and is not fixed to the processor assembly. It's not going to bend or bow. The HEAT SPREADER is much thinner and is attached directly to the processor assembly. Depending on just how it's attached, it might bend or bow under heat stress. I don't have an Athlon here I can take apart to see where the attachment points are, but it's something worth looking at.
The point of my post is that IF bowing occurs, it has the potential to be a surpisingly large effect. To see what I mean, take two pieces of paper or index cards and place one on top of another. Then, keeping one edge in place, move the other edge of the top card a fraction of a millimeter towards the other. You'll see the card bow out to a much larger distance than you moved the edge. Bowing magnifies heat expansion differences.
I don't take my numbers too seriously. They are just a back of the envelope, order of magnitude calculation, to show what effects thermal expansion can have under certain circumstances. The only way to know if this actually does happen is to measure the flatness of a hot heat spreader in situ.
I have some experience with heat deformation. I did an internship at the National Insitute of Standards and Technology (Metrology Section/Optical Physcis Division) working on computer-controlled measuring machine that required a large flat steel plate as its base The major problem was that any slight temperature gradients in the plate caused microscopic deformations that affected the precise measurements we were making. We had the plate covered in a grid of tiny thermocouples to ascertain and eliminate or compensate for the temperature gradients.
As I said, just because something is flat when it's cold, doesn't mean it's flat when it's hot.
Sorry, I forgot a factor of 1/2 when I wrote that post. It was 5:40am (geek bedtime) when I wrote it, so by the time I realized it, I was in bed.
The formula should read:
B=(1/2)*Square root of ((L+sigma)2 -(L)2)
So the result should be
B=.045 rather than B=.09
.045 inches is still a very large degreee of bowing, however, so my point still stands. If bowing of the heat spreader occurs then it will cause large errors in surface flatness.
BTW, I am talking about bowing of the heat spreader not the heat sink. The heat sink is a thick piece of aluminum and it not directly fixed to the processor assembly. It's not going to deform. The heat spreader, which is attached to the processor assembly, is much thinner and depending on where it is attached it could warp somewhat.
If it's flat when it's cold, is it flat when it's hot?
The coefficient of linear thermal expansion is:
Aluminum: 25 x 10-6 (C)-1
Silicon: 3 x 10-6 (C)-1
Difference: 22 x 10-6 (C)-1
If you attach a sheet of aluminum to a wafer of silicon the aluminum will expand more than the silicon. The difference in the expansion will be 22 x 10-6 of an inch per inch per degree centigrade.
For a 4 inch piece of aluminum heated ten degrees the difference will be approximately.001 inches.
If the plate is fixed at the ends it may bow out. The amount that the bowing will pull the aluminum away from the silicon is approximately:
B=Square root of ((L+sigma)2 -(L)2)
Where L is the length and sigma is the expansion difference. For sigma much smaller than L this is approximately:
B=Square root of (2L*sigma)
If L=4 inches and sigma=.001inches
B=Square root of (.008)
B=.09 inches
That's almost a tenth of an inch. That's on the order of fifty times larger than any surface imperfections.
Now, I've admittedly made a lot of simplifying assumptions in my calculations. Some of them, if anything, underestimate the bowing factor.(Only ten degrees above room temperature--that's a well cooled processor indeed.)
But the magnitude of the effect of any bowing due to differential thermal expansion is so large, that if it does occur it would dwarf other departures from flatness.
So attention must be paid to how and where the alumium is attached to the silicon (as well as joints between other substances) to be sure such thermal bowing does not occur when the computer is actually running.
The Eponymous Mallard
If it walks like a duck...it's the Eponymous Mallard
Slashdot Mirror
It's all about two words, "copy protection." Take a look at the following page from MS research on the "Secure PC": http://research.microsoft.com/crypto/openbox.asp "Essentially, this would turn the PC into a record player as far as music is concerned, while preserving the other open aspects of the computer. Record companies could release their records in an encrypted, unable to be copied Windows Media Audio format that would only work on the secure version of the Windows Media Player. A similar arrangement could be reached with the movie studios for film distribution..." "He [Microsoft Research cryptographer Paul England] says an agreement between software and hardware makers is near, and "we should see some hardware for content protection within a year." Microsoft is already shipping a secure version of Windows Media Player. England is pretty sure that it will be cracked eventually, but he says it will do for now. The way to slam the door on the pirates lies in a modification of the hardware, he says. "We must make it immune to a software attack, and close the PC in that way." ..."
So the idea is to embed content protection into the PC from the operating system down to the hardware. So how does this relate to USB? Well, there is no copy protection built into the USB specification. But there will be copy protection support built into the 1394 (Fire Wire) standard, as announced by the 1394 Trade Association (of which MS is a member) three weeks ago.
http://www.1394ta.org/Press/2001Press/mar/3.21.a.h tm
"SANTA CLARA, Calif.--(BUSINESS WIRE)--March 21, 2001-- The leaders of the 1394 Trade Association today urged the consumer electronics and computer industries to adopt the comprehensive digital copy protection system known as Digital Transmission Copy Protection, or ``5C,'' developed by leaders of the electronics industry to prevent unauthorized use of copy-protected content..."
Other members of the 1394 Trade Association include Sony, Philips, Intel, Texas Instruments, Panasonic, Canon, Fujitsu, Compaq and many more.
Six days after the announcement of 1394 support of copy protection, Microsoft confirmed that it would not support USB in Windows XP.
http://www.theregister.co.uk/content/2/17919.html
1394 will incorporate support for DTCP copy protection designed by the 5C group (Sony, Intel, Toshiba, Matushita, and Hitachi):
http://www.dtcp.com/spec.html
"To allow for protected transmission of copy-protected material between digital devices like PC's, DVD Players, and Digital TV's, five companies -- Hitachi, Intel, Matsushita (MEI), Sony and Toshiba have prepared the "5C" Digital Transmission Content Protection (DTCP) specification..."
"The DTCP specification defines a cryptographic protocol for protecting audio/video entertainment content from illegal copying, intercepting and tampering as it traverses high performance digital buses, such as the IEEE 1394 standard."
Microsoft is acting in cooperation with content providers (the music, movie, and video game industry) and with hardware makers to produce a totally copy-protected ("secure") PC. That way the movie and music people can get a payment each time you play a file, and MS will also get its cut. It is essential that copy protection be put into the hardware, since otherwise consumers would be tempted to operating systems without copy protection such as Linux. You will get a music file, from say, Sony, with built-in copy protection, over MS.NET (with possible built in copy protection filters) downloaded to your (copy protected) hard drive, played by MS Media Player (with built in copy protection) running on Windows XP (with copy protection support) and transmitted via the copy protected 1394 bus. It's multi-layered protection and the bus is the last line of defense.
So USB (no built-in copy protection) has to go, and 1394, with built-in copy protection support, gets Windows support from now on.
My analysis would be naive if I were talking about the heatsink. But read the web page that started the discussion. They didn't measure the flatness of the HEAT SINK. They measured the flatness of the PROCESSOR HEAT SPREADER. It's an entirely different object.
The HEAT SINK is a bulky piece of aluminum and is not fixed to the processor assembly. It's not going to bend or bow. The HEAT SPREADER is much thinner and is attached directly to the processor assembly. Depending on just how it's attached, it might bend or bow under heat stress. I don't have an Athlon here I can take apart to see where the attachment points are, but it's something worth looking at.
The point of my post is that IF bowing occurs, it has the potential to be a surpisingly large effect. To see what I mean, take two pieces of paper or index cards and place one on top of another. Then, keeping one edge in place, move the other edge of the top card a fraction of a millimeter towards the other. You'll see the card bow out to a much larger distance than you moved the edge. Bowing magnifies heat expansion differences.
I don't take my numbers too seriously. They are just a back of the envelope, order of magnitude calculation, to show what effects thermal expansion can have under certain circumstances. The only way to know if this actually does happen is to measure the flatness of a hot heat spreader in situ.
I have some experience with heat deformation. I did an internship at the National Insitute of Standards and Technology (Metrology Section/Optical Physcis Division) working on computer-controlled measuring machine that required a large flat steel plate as its base The major problem was that any slight temperature gradients in the plate caused microscopic deformations that affected the precise measurements we were making. We had the plate covered in a grid of tiny thermocouples to ascertain and eliminate or compensate for the temperature gradients.
As I said, just because something is flat when it's cold, doesn't mean it's flat when it's hot.
The Eponymous Mallard
You can't accuse me of "ducking" the question.
Sorry, I forgot a factor of 1/2 when I wrote that post. It was 5:40am (geek bedtime) when I wrote it, so by the time I realized it, I was in bed.
The formula should read:
B=(1/2)*Square root of ((L+sigma)2 -(L)2)
So the result should be
B=.045 rather than B=.09
.045 inches is still a very large degreee of bowing, however, so my point still stands. If bowing of the heat spreader occurs then it will cause large errors in surface flatness.
BTW, I am talking about bowing of the heat spreader not the heat sink. The heat sink is a thick piece of aluminum and it not directly fixed to the processor assembly. It's not going to deform. The heat spreader, which is attached to the processor assembly, is much thinner and depending on where it is attached it could warp somewhat.
The Eponymous Mallard
graccito ergo sum
I quack, therefore I am
If it's flat when it's cold, is it flat when it's hot?
.001 inches.
The coefficient of linear thermal expansion is:
Aluminum: 25 x 10-6 (C)-1
Silicon: 3 x 10-6 (C)-1
Difference: 22 x 10-6 (C)-1
If you attach a sheet of aluminum to a wafer of silicon the aluminum will expand more than the silicon. The difference in the expansion will be 22 x 10-6 of an inch per inch per degree centigrade.
For a 4 inch piece of aluminum heated ten degrees the difference will be approximately
If the plate is fixed at the ends it may bow out. The amount that the bowing will pull the aluminum away from the silicon is approximately:
B=Square root of ((L+sigma)2 -(L)2)
Where L is the length and sigma is the expansion difference. For sigma much smaller than L this is approximately:
B=Square root of (2L*sigma)
If L=4 inches and sigma=.001inches
B=Square root of (.008)
B=.09 inches
That's almost a tenth of an inch. That's on the order of fifty times larger than any surface imperfections.
Now, I've admittedly made a lot of simplifying assumptions in my calculations. Some of them, if anything, underestimate the bowing factor.(Only ten degrees above room temperature--that's a well cooled processor indeed.)
But the magnitude of the effect of any bowing due to differential thermal expansion is so large, that if it does occur it would dwarf other departures from flatness.
So attention must be paid to how and where the alumium is attached to the silicon (as well as joints between other substances) to be sure such thermal bowing does not occur when the computer is actually running.
The Eponymous Mallard
If it walks like a duck...it's the Eponymous Mallard