If you want a job in the high tech field, you must be prepared to move to another city. Go where the jobs are. If you stick around in your jobless area, you'll be lucky if you find a job ever by the sounds of it.
>>Expect to spend a significant amount of time explaining "Windows Equivalents" to your users. Cut and Paste for example, can be a PITA.
That's got to be the #1 biggest complaint. It's high time that Cut & Paste in a graphical environment was changed to CTRL-C and CTRL-V. And it should persist to the clipboard - not be overwritten so easily. Leave the console cut/paste the way it is because it's handy within that environment.
Lots of mirrors, but it doesn't look like we'll need 'em. Downloaded at 10:45PM PDT at the max speed of my DSL! Had to go through my Opera cache to be able to play it twice, though.
My current feelings: What a GREAT idea. I think these guys are on the right track, and it's nice to see another big player trying to level the playing field. I'm sure they will gain huge support from consumers. I'm also sure they expect to make a few bucks while they're at it.;)
I don't like the thought of a "tax", though. Tax money isn't always used for what it's original intent was. Maybe that should be more like "never". Then you have corruption where the money gets siphoned into someone's pocket. Also, everyone gets lumped into the same pot where everyone pays, but not everyone benefits or wants that benefit. Not everyone will want to download music via the Internet.
When you also figure in that someday billions of devices will be plugged into the Internet, it's very likely that a lot of people won't even surf the web but still will have Internet access to hook their devices up (for whatever reason). Making these people pay a music tax is not reasonable.
You also have the problem of other industries jumping on the bandwagon once the precedence has been set. Suppose the e-book industry decides that there is way too much piracy going on - so they would also like an Internet tax levied on everyone. Personally, I've never bought an e-book and can't say I have any plans to buy one currently. Why should I pay a tax on that?
I like the idea of www.emusic.com. Download all you want for a fixed price. Call it a "user fee" if you wish. Often that's an alternative to high taxes. In this case, it's the principle that I'm focusing on, not the one dollar.
One final opinion - I think taxing CDRs is _ridiculous_. In my honest opinion, it's the only really viable backup solution for me. Why would I pay a music tax?
He didn't complain when he had the monopolist on his side, though? If course Microsoft is the "referee". The fact that he didn't see that was a sure sign that his company would fail.
Yeah... I know. I'm providing input on the countries *I* have personally lived in. I hope that people who live in other countries will stick up for themselves.
Voice-over-IP companies seem to be targetting price, when really the price of long distance calls is basically 5 cents/minute within and between Canada and the US if you shop around.
I think VoIP should be coming up with new, must have features to sell their products, and couple that with an also low price.
Did anyone else notice the blatant Star Wars ad displayed with every image window popup?
Is this a new form of advertising? Spend $1,000 on some game consoles, do something funky with'em, and sell advertising rights on the resultant slashdotted site?
Finally, some new news (as opposed to "this is nothing new").
Question - why is it that we JUST found out about this? How long did it take to build this giant supercomputer? Companies like IBM talk about what they're building long before they are done. Speaking of which, I guess IBM's Deep Blue is kinda underpowered now, relatively speaking.
One more thing - why all the hub-bub about US export restrictions re: computer power? If Japan already has this much computing power, who wants our "junk" anyway? I lied - one more thing - does the NSA have penis envy over this? Or is their computer still faster?;)
Here's the whole thing for those who are interested... I'd try and draw the images, but my ASCII art is a little out of practice.;) ------
The Case of the Exploding CD-ROM Record
Epsilon Omega City, 2025 AD. Photographer: Jörgen Städje
32x, 56x, 64x... CD-ROM Readers are Getting Faster
Contents
Introduction Background
CAV is for Whimps
CLV is for the Tough Boys Experimental Set-Up Test Run G Forces in the Disc Kevlar Reinforced CD- Record Results Suggestions for Methods of Achieving Higher Data Transfer Rates
Multiple Tracks
Multiple Reading Heads
Kevlar Lamination
Caching Safety Recommendations Summary Appendices
Appendix A. Table of Results
Appendix B. Charts ___Chart 1. Rotational Speed of Destruction (wd) ___Chart 2. Peripheral Speed at Rotational Speed of Destruction (vp) ___Chart 3. Peripheral Speed as a Percentage of the Speed of Sound (vp%c) ___Chart 4. Power Dissipation of the Record at 24000 rpm (P24000)
Appendix C. Glossary
Introduction
But where's the limit? Manufacturers try to outspin each other all the time by selling CD-ROM drives with higher and higher spin ratios. Spin ratios of 2x, 4x, 8x, 16x, 32x, 56x and 64x come in a never ending stream. The CD is forced to rotate faster and faster. At what speed will a CD blow up, and can you do something to prevent it from exploding?
I decided to investigate all facts of the case:
How high speeds can various types of CD's take (for example CD-ROM's and CD-R's)? Can one do something to make them stand even greater speeds? What is the result when the limit is exceeded? Are there other possible measures to increase the data transfer rate further?
The case was scientifically investigated at the electronics labs of Atlas Copco AB in Tyresö, outside Stockholm. We used a motor capable of 30,000 revolutions per minute, and a specially machined hub to keep the CD record as vibration-free as possible.
Background
The Audio CD Standard was set sometime back in the 70's. Then, it was decided that the record should rotate with different speeds, depending on where on the record the data was read, to get a constant data transfer rate. The method is named CLV (Constant Linear Velocity), or constant transfer rate. The transfer rate of an audio CD is a mere 176 kB/s, and to reach this rate the record only has to spin with 530 rpm when reading the innermost track, and 200 rpm for the outer track.
CAV is for Whimps
To be able to publish ever increasing spin ratios, many manufacturers have resorted to CAV (Constant Angular Velocity), a method whereby the record is not rotated faster when reading inner tracks. Thus they can specify impressive spin ratios for outer tracks and sell more, but in reality the spin ratio for the inner tracks is only 37.7% of this value.
CLV is for the Tough Boys
A 64x drive using CLV would have to rotate the disc with 33,920 rpm when reading an inner track, exposing the hub of the disk to a tangential force of some 45 N/mm2. A point on the periphery of the disc will be moving with 213 metres per second, slightly more than half the speed of sound. Can the disc take that?
The answer is no. A powerful no.
At about 52x, i.e. 27,500 rpm, most manufacturer's CDs blew up in a rain of plastic particles, leaving their marks on the premises. The result was a pile of shimmering plastic chips.
Experimental Set-Up
The CD-ROM which was to be strength tested was mounted inside damage-resistant testing equipment in a soundproofed room, complete with a shatterproof observation window.
The device under test A, was mounted to the hub B with a stud and a number of centering and holding washers in plastic material. The hub B was machined into the shaft of motor C, a three-phase motor for industrial washing machines. D was a sensor, sensing rotational speed and E1 and E2 the lower and upper shrapnel protectors, respectively, manufactured from 1.0 mm aluminium. F was the heavily armoured wall of the testing chamber, provided with a shatterproof observation window made of an amorphous silicon compound.
As you may see, the electronic equipment is extensive and very advanced. To the far left is a digital-analogue three-phase generator (a drive) able to deliver 10 Amps and 600 Volts with controllable frequency up to 1000 Hz, to run the connected motor up to 30,000 rpm. The drive is controlled by a portable PC, an advanced model when it was bought in 1985, today specially adapted as control terminal for our explosive experiments. Behind this you may see, carefully arranged, lots of other advanced equipment, such as an advanced roll of tape, a high tech plastic container, some superconducting cables and to the far right, an advanced roll of soldering tin (red).
The technician Thord Nilson (Ye Olde Wizarde), under maximum spiritual concentration and greatest possible silence, conducts manual balancing of one device under test. The tool in his hand, a Borkhardt SMS4579-A is used for tightening the fastening attachment in the centre of the hub (B in the picture above). The equipment in the background, the green cylinder, is a secret part of Atlas Copco's research work, a so called Spluriser. Because of this, you should forget it immediately.
Test Run
The test was conducted in such a manner that the DUT (Device Under Test) was mounted as vibration-free as possible in the test equipment, the personnel left the room, the room was hermetically sealed, protective clothing was donned, and we took up a safe position at the observation window.
The rotational speed was slowly increased from zero (ramping) towards 30,000 rpm and the operational parameters were recorded at the point of breaking.
The disc manufacturer, speed at destruction, power loss, temperature etc., were carefully recorded and became the basis of the "Table of Result", in Appendix A.
This was repeated for all eleven DUTs. It is worth noting that we increased the speed manually in the beginning, but later changed and let the explosion-control electronics increase the speed (direct ramping). The latter resulted in a somewhat increased durability of the DUT, usually a few thousand rpms.
Also note that the whining of the motor, the vibrations in the walls and the roaring of the CD-ROM disc, not unlike the sound of a crashing jet aeroplane, was impressive, and of course drew great interest from the staff at neighbouring laboratories.
When the disc fractured, there was a sharp bang and the test chamber was filled with shimmering, glittering shrapnel, and our grins were big. We hurried in and mounted the next disc, to be able to shoot again as fast as possible.
G Forces in the Disc
At 30,000 rpm the periphery of the disc is subjected to over 1500 g, and the hub is subjected to a force of 35 N/mm2 on its inner side. It is this force that will ultimately break up the disc.
Kevlar Reinforced CD Record
In our efforts of reaching ever increasing speeds, we tried to reinforce a disc with Kevlar wires. The wire was wound across the disc, as seen in the first picture. As Kevlar needs some pre-tensioning, the disc shows some warping when resting, as seen in the second picture. The warping disappears at increased speeds, though.
Kevlar is the strongest material in existence, many times stronger than unhardened steel and sewing thread. The wire we used, had an ultimate tensile strength of 80 N. As the wire was wound 5 times around the same point on the disc periphery, the wire bundle had a total ultimate tensile strength of 400 N (enough to hang a bicycle in).
It turned out our motor didn't have enough power to spin up the disc enough to explode it in one try, because the Kevlar wires consumed several hundred watts of motor power for aerobreaking.
After an extended period of time (about 20 seconds) at close to 28,000 rpm, the disc blew up with a loud bang anyway, with the wires remaining on the hub, as shown in the picture. It can be clearly seen that the wires remains pointing radially from the hub. The Kevlar wires had been stretched radially and performed as intended. What made the disc explode, was the creepage of the plastic material, i.e. its stretching over time, subjected to the high g forces.
Results
The result surpassed our wildest hopes, sorry: the result was scientifically convincing. The premises and the test equipment also became slightly modified during the testing.
The CD fragments left the disc at such high ejection speed that they deformed the shrapnel protectors, made out of 1.0 mm aluminium. The protectors were dented, torn up, and knocked off their fastening bolts.
One fragment has hit the protector with such force, that the metal has been torn up in an 8 mm rift. It is not probable that the fragment passed through the crack.
At a pre-test, performed without shrapnel protection, long rifts were torn in the ceiling, as shown in the picture. The speed sensor also had its surface coating ripped off.
Decontamination of the premises was time consuming, and yet it was not possible to recover all the shrapnel. We did remove so much, that there is no longer any great risk of damage to the environment or the climate. The picture shows the nice collection of plastic pieces remaining after the tests.
A close-up of the shrapnel, showing its enormous diversity, and its interesting colour characteristics. The self-tapping screw visible in the middle left, BZX4x12, galvanised steel, is not attributable to our experiment, but has to be ascribed to the extremely carefully, close to exaggeration, carried out decontamination process.
This final picture, shows the fragments in detail. You may study the breakage surfaces and the individual chips. It should be noted that we still haven't finished the scanning electron microscopic studies, so probably all details haven't been revealed yet. At the bottom right, the text "Corel Corporation" is visible.
Suggestions for Methods of Achieving Higher Data Transfer Rates
It is obvious the CD-ROM's are too brittle for rotational speeds over 23,000 rpm. As the speed is such a limiting factor for increasing the data transfer rate from CD-ROM records, other resolutions must be sought. Either the method of readout, or the medium should be changed.
Multiple Tracks
As most files take up more than one track on the record, it would be desirable to try to read more than one track at a time. Suppose you exchange today's reading phototransistor for a CCD array and read, for example 100 tracks at a time. This would increase the transfer speed 100 times, without the need for increasing rotational speed.
Multiple Reading Heads
For multi-user applications it would be feasible to use three or four reading heads together on the same CD record. This would need mounting four reading mechanisms at 90 degrees angle to each other in the same drive. If the same user was using all the four heads, intelligent caching could be used for increasing the transfer rate. Otherwise, four users would be able to read at four different places on the disc at the same time, with the four users experiencing increased reading speed, compared to the case of using one reading head and time-shared access.
Kevlar Lamination
Lamination with Kevlar fabric is an obvious solution. Not only does this render the disc capable of standing 20,000 rpm, but as the Kevlar fabric will have to be sandwiched between two CD records, preferably glued label-to-label, the record will be double-sided, thus having double the storage capacity of today's records, about 1.3 GB. Because it is possible to read both sides at the same time, readout speed is again doubled. The motor power required, some 300 watts, would impose a rather heavy loading on the computer's power supply, though.
Caching
It would be possible to build a hard disk into the CD-ROM drive. When a record is inserted into the drive, it will automatically start to read information onto the hard disk. All user accesses will go to the hard disk and all the advantages of the hard disk will be available, such as access times of less than 10 ms, and latency times in the order of 3-4 ms. Hard disks with the capacity to store an entire CD-ROM, today cost no more than a standard quality CD-ROM drive, so a cached CD-ROM drive would command a price of no more than 1.7-1.8 times the price of an un-cached one. This is no great hindrance for the ordinary consumer.
Safety Recommendations
The committee wishes, after finishing its work, to suggest the following safety precautions.
Safe distance to a CD-ROM drive with spin ratio 64x CLV should be no less than 5 metres (15 ft.). All work with CD-ROM units should require safety goggles and protective clothing be worn. CD-ROM drives of the 64x CLV class and higher, should be provided with shrapnel protection of no less than 3 mm aluminium or 1 mm steel. To avoid operator inhalation of CD-ROM particles, CD-ROM drives should be provided with a dust suction fan with suitable filter, or have the fan duct connected directly to the outside air. In addition to the laser light warning label, CD drives should be affixed with another label warning against the hazard of shrapnel, such as the one below:
Summary
CD-ROM drives with spin factors higher than 64x are impossible to build, as most records reach their ultimate strength limit at this speed. Instead, other solutions have to be sought, such as using several read heads, reading several tracks at at a time, or the like.
The general recommendation is that you never stand close to a 64x drive, if it isn't mounted in an explosion proof enclosure. You could have your stomach perforated.
Appendices
Appendix A. Table of Results
No. Type wd vp vp%c P24000 Notes
1 CD-R, Maxell 27000 170 49.87 86 Type CD-R74XL
2 CD-ROM, CorelDRAW 6 24000 151 44.33 86
3 CD-ROM, CorelDRAW 6 23000 144 42.48 86 Heavily maltreated with a blunt object
4 CD-ROM, CorelDRAW 8 25020 157 46.21 86
5 CD-R, Maxell 25020 157 46.21 86 Type CD-R74XL
6 CD-ROM, Ventura 7 26200 165 48.39 86 From this record on, direct ramping was employed
7 CD-ROM, WP Suite 8 27400 172 50.61 86 Lots of printing on
8 CD-ROM, CorelDRAW 6 27900 175 51.53 330 Kevlar reinforced. Blew up after long time
9 CD-ROM, Ventura 7 27900 175 51.53 86
10 CD-ROM, CorelDRAW 6 27900 175 51.53 86
11 CD-ROM, WP Suite 8 28600 180 52.83 86 Lots of printing on
wd: Rotational Speed of Destruction (rpm) vp: Peripheral Speed at Rotational Speed of Destruction (m/s) vp%c: Peripheral Speed as a Percentage of the Speed of Sound (% of 340 m/s) P24000: Power consumption of the record at 24,000 rpm (W)
Comment: It is obvious that a higher wd can be achieved by direct ramping of the speed than manual ramping, as the manual ramping takes longer time. The creepage of the plastic material plays a major part in how long it takes before the disc explodes.
Appendix B. Charts
Chart 1. Rotational Speed of Destruction (wd)
Comments: The Kevlar reinforced record, no. 8., would have reached 30,000 rpm, but our motor didn't make it. Disc no. 3 was impact tested with a heavy tool, which is why it cracked so early.
Chart 2. Peripheral Speed at Rotational Speed of Destruction (vp)
Comment: None of the discs reached more than 180 m/s, but on the other hand that's about 650 km/h, the cruising speed of a jet airliner.
Chart 3. Peripheral Speed as a Percentage of the Speed of Sound (vp%c)
Comment: With our 180 m/s maximum, we were far from the sound barrier. The speed of sound is 340 m/s. Hence, a CD-ROM cannot make sonic booms, at least not rotation-wise.
Chart 4. Power Dissipation of the Record at 24,000 rpm (P24000)
Comment: At these speeds a CD-ROM takes about 80-90 W. It does heat up a lot. The Kevlar reinforced record, no. 8, used a lot more power because of the aerobreaking effect of all the Kevlar wires. But it looked much groovier.
Appendix C. Glossary
CLV: Constant Linear Velocity, or constant data transfer speed, meaning that the record is always rotated with such a speed that the readout speed is constant, irrespective of which track is read.
CAV: Constant Angular Velocity, meaning that the record is rotated at constant speed, making the readout speed higher on an outer track than on an inner track. Something to be avoided.
Spin factor: Typeless constant indicating the number of times the CD drive in question rotates faster than an audio CD. Designation: x. An audio player is 1x, meaning 530 rpm when reading an inner track, and 200 rpm reading an outer track. CLV is employed.
First off, why doesn't Bill Gates mention the LGPL?
>>So, $200 for WinXP is 4% the price of a $500 PC. Great math there Bill.
LOL. One of your other respondents says PC manufacturers don't pay retail... I wonder then why the off the shelf copy costs so much if the OEM version is like $20?
>>That's great, you use the API's, don't worry about the fact you've just tied yourself into only one vendor that can ever fix the API, or know what it *really* does...
Yes, Bill is totally assuming that the APIs themselves are 100% open, which of course is NOT the case with Windows APIs.
In closing, I'd just like to say that I hope there were some smart people in the audience and not just people who came to hear Bill Gates' jokes (laughter). Bill's company is under investigation for ANTI-TRUST violations... and yet his opinions are still solicited. Think about the meaning - anti...trust. His company broke the trust. A friend like this might be called a Back Stabber. How would you treat a friend like that?
I think the government should stop listening to Microsoft until the antitrust suits against them have completed and remedies have been applied.
Why on God's Green Earth is the government still soliciting Microsoft's opinion on what is right and wrong? Microsoft is obviously guilty of many charges and for some reason has even escaped the charge of purgery. Makes you wonder if the gov't even cares that Microsoft has broken the law so many times. Maybe it's all a show.
Anyway, if everyone goes out and buys a processor from a company with a reject CEO, why would the board of directors ever let the CEO go? The CEO is supposed to reflect the opinions of the company, and since I strongly disagree...
Honestly, what he's been quoted as saying sounds exactly like a Microsoft line. I wouldn't be surprised if the people who write Bill's speeches wrote this one as well.
UNBELIEVABLE... seriously, I was going to buy my first AMD processor in the next couple of weeks. It's obvious that they're in Microsoft's pockets now... guess it'll be an Intel for me, thank you. Their prices will be dropping soon anyway.
I used to live in Canada. They threatened to do this 2-3 years ago as I recall... but for some reason did not. Finally, the insanity of it all has come to light. What a shame.
I also remember that when cigarettes when to $8 a pack, smuggling skyrocketed, and the government backed off so they were back down to the $4 range (don't know what they are now up there). I hope the same thing happens with CDR's, etc...
I bet they're kicking their asses now for not taking all the land they discovered. I wonder why they didn't start colonizing? Maybe at the time it wasn't feasible...?
With Pacific Bell (and probably most other providers), they will divvy up the days of downtime you had, then subtract the pro-rated amount off your bill. You won't get a free month with these guys, trust me. You don't get a red cent for the hours you waste on the phone with tech support, and you also don't get anything for waiting hours and hours for a technician to arrive. That's not even getting into the lost productivity...
7,400,000,000 miles = 119,066,000,000 kilometers speed of light = 299,792,458 meters per second which equals 299,792.458 kilometers per second
119,066,000,000 / 299,792.458
approximately equals 397,161 seconds which equals 110.3225 hours
So, if the Pioneer spacecraft were going the speed of light from the beginning, it would have only taken it less than 5 days to get where it is today, 30 years later. Wow! Anyone getting close to inventing speed of light travel yet?
Parent and parent's parent are the best I've heard summing up creativity. Great posts.
I remember working with lego, meccano, capsula, playdoh, a plastic building kit (can't remember the name), armatron, and working with wood, tools, bicycles, pipes, cardboard, you name it. And of course, taking things apart and usually getting them back together (with a few spare pieces of course).:)
This is a part of my life I will always remember and, even though I'm into computers today, I will try and pass the above creativity down to my kids someday. I'm very happy I had the chance to do these things.
It is an open source project with AFAIK, to date, no patented code in it. So, if I decide to take a CVS snapshot today and maintain a new branch of it, there should be nothing stopping me and no way to "kill it".
Slashdot Mirror
If you want a job in the high tech field, you must be prepared to move to another city. Go where the jobs are. If you stick around in your jobless area, you'll be lucky if you find a job ever by the sounds of it.
>>Expect to spend a significant amount of time explaining "Windows Equivalents" to your users. Cut and Paste for example, can be a PITA.
That's got to be the #1 biggest complaint. It's high time that Cut & Paste in a graphical environment was changed to CTRL-C and CTRL-V. And it should persist to the clipboard - not be overwritten so easily. Leave the console cut/paste the way it is because it's handy within that environment.
Lots of mirrors, but it doesn't look like we'll need 'em. Downloaded at 10:45PM PDT at the max speed of my DSL! Had to go through my Opera cache to be able to play it twice, though.
My current feelings: What a GREAT idea. I think these guys are on the right track, and it's nice to see another big player trying to level the playing field. I'm sure they will gain huge support from consumers. I'm also sure they expect to make a few bucks while they're at it. ;)
I don't like the thought of a "tax", though. Tax money isn't always used for what it's original intent was. Maybe that should be more like "never". Then you have corruption where the money gets siphoned into someone's pocket. Also, everyone gets lumped into the same pot where everyone pays, but not everyone benefits or wants that benefit. Not everyone will want to download music via the Internet.
When you also figure in that someday billions of devices will be plugged into the Internet, it's very likely that a lot of people won't even surf the web but still will have Internet access to hook their devices up (for whatever reason). Making these people pay a music tax is not reasonable.
You also have the problem of other industries jumping on the bandwagon once the precedence has been set. Suppose the e-book industry decides that there is way too much piracy going on - so they would also like an Internet tax levied on everyone. Personally, I've never bought an e-book and can't say I have any plans to buy one currently. Why should I pay a tax on that?
I like the idea of www.emusic.com. Download all you want for a fixed price. Call it a "user fee" if you wish. Often that's an alternative to high taxes. In this case, it's the principle that I'm focusing on, not the one dollar.
One final opinion - I think taxing CDRs is _ridiculous_. In my honest opinion, it's the only really viable backup solution for me. Why would I pay a music tax?
He didn't complain when he had the monopolist on his side, though? If course Microsoft is the "referee". The fact that he didn't see that was a sure sign that his company would fail.
The site I've visited in the past is:
http://www.nitpickers.com
Amen, brother. :)
Yeah... I know. I'm providing input on the countries *I* have personally lived in. I hope that people who live in other countries will stick up for themselves.
Interesting - if you go to the Internet2 home page, I wonder if that map of the Internet2 backbone in the United States is accurate? Internet2
The reason I ask is - it looks awfully dependent upon connections located near the shores of the US. What if the US was attacked?
Voice-over-IP companies seem to be targetting price, when really the price of long distance calls is basically 5 cents/minute within and between Canada and the US if you shop around.
I think VoIP should be coming up with new, must have features to sell their products, and couple that with an also low price.
Did anyone else notice the blatant Star Wars ad displayed with every image window popup?
Is this a new form of advertising? Spend $1,000 on some game consoles, do something funky with'em, and sell advertising rights on the resultant slashdotted site?
LOL... well, I'll give it an 'A' for creativity.
Finally, some new news (as opposed to "this is nothing new").
;)
Question - why is it that we JUST found out about this? How long did it take to build this giant supercomputer? Companies like IBM talk about what they're building long before they are done. Speaking of which, I guess IBM's Deep Blue is kinda underpowered now, relatively speaking.
One more thing - why all the hub-bub about US export restrictions re: computer power? If Japan already has this much computing power, who wants our "junk" anyway?
I lied - one more thing - does the NSA have penis envy over this? Or is their computer still faster?
Is it possible for the ink on a CD-ReWritable disc to be forced outward by the centrifugal force, thereby hosing your disc?
Here's the whole thing for those who are interested... I'd try and draw the images, but my ASCII art is a little out of practice.
------
The Case of the Exploding CD-ROM Record
Epsilon Omega City, 2025 AD. Photographer: Jörgen Städje
32x, 56x, 64x...
CD-ROM Readers are Getting Faster
Contents
Introduction
Background
CAV is for Whimps
CLV is for the Tough Boys
Experimental Set-Up
Test Run
G Forces in the Disc
Kevlar Reinforced CD- Record
Results
Suggestions for Methods of Achieving Higher Data Transfer Rates
Multiple Tracks
Multiple Reading Heads
Kevlar Lamination
Caching
Safety Recommendations
Summary
Appendices
Appendix A. Table of Results
Appendix B. Charts
___Chart 1. Rotational Speed of Destruction (wd)
___Chart 2. Peripheral Speed at Rotational Speed of Destruction (vp)
___Chart 3. Peripheral Speed as a Percentage of the Speed of Sound (vp%c)
___Chart 4. Power Dissipation of the Record at 24000 rpm (P24000)
Appendix C. Glossary
Introduction
But where's the limit? Manufacturers try to outspin each other all the time by selling CD-ROM drives with higher and higher spin ratios. Spin ratios of 2x, 4x, 8x, 16x, 32x, 56x and 64x come in a never ending stream. The CD is forced to rotate faster and faster. At what speed will a CD blow up, and can you do something to prevent it from exploding?
I decided to investigate all facts of the case:
How high speeds can various types of CD's take (for example CD-ROM's and CD-R's)?
Can one do something to make them stand even greater speeds?
What is the result when the limit is exceeded?
Are there other possible measures to increase the data transfer rate further?
The case was scientifically investigated at the electronics labs of Atlas Copco AB in Tyresö, outside Stockholm. We used a motor capable of 30,000 revolutions per minute, and a specially machined hub to keep the CD record as vibration-free as possible.
Background
The Audio CD Standard was set sometime back in the 70's. Then, it was decided that the record should rotate with different speeds, depending on where on the record the data was read, to get a constant data transfer rate. The method is named CLV (Constant Linear Velocity), or constant transfer rate. The transfer rate of an audio CD is a mere 176 kB/s, and to reach this rate the record only has to spin with 530 rpm when reading the innermost track, and 200 rpm for the outer track.
CAV is for Whimps
To be able to publish ever increasing spin ratios, many manufacturers have resorted to CAV (Constant Angular Velocity), a method whereby the record is not rotated faster when reading inner tracks. Thus they can specify impressive spin ratios for outer tracks and sell more, but in reality the spin ratio for the inner tracks is only 37.7% of this value.
CLV is for the Tough Boys
A 64x drive using CLV would have to rotate the disc with 33,920 rpm when reading an inner track, exposing the hub of the disk to a tangential force of some 45 N/mm2. A point on the periphery of the disc will be moving with 213 metres per second, slightly more than half the speed of sound. Can the disc take that?
The answer is no. A powerful no.
At about 52x, i.e. 27,500 rpm, most manufacturer's CDs blew up in a rain of plastic particles, leaving their marks on the premises. The result was a pile of shimmering plastic chips.
Experimental Set-Up
The CD-ROM which was to be strength tested was mounted inside damage-resistant testing equipment in a soundproofed room, complete with a shatterproof observation window.
The device under test A, was mounted to the hub B with a stud and a number of centering and holding washers in plastic material. The hub B was machined into the shaft of motor C, a three-phase motor for industrial washing machines. D was a sensor, sensing rotational speed and E1 and E2 the lower and upper shrapnel protectors, respectively, manufactured from 1.0 mm aluminium. F was the heavily armoured wall of the testing chamber, provided with a shatterproof observation window made of an amorphous silicon compound.
As you may see, the electronic equipment is extensive and very advanced. To the far left is a digital-analogue three-phase generator (a drive) able to deliver 10 Amps and 600 Volts with controllable frequency up to 1000 Hz, to run the connected motor up to 30,000 rpm. The drive is controlled by a portable PC, an advanced model when it was bought in 1985, today specially adapted as control terminal for our explosive experiments. Behind this you may see, carefully arranged, lots of other advanced equipment, such as an advanced roll of tape, a high tech plastic container, some superconducting cables and to the far right, an advanced roll of soldering tin (red).
The technician Thord Nilson (Ye Olde Wizarde), under maximum spiritual concentration and greatest possible silence, conducts manual balancing of one device under test. The tool in his hand, a Borkhardt SMS4579-A is used for tightening the fastening attachment in the centre of the hub (B in the picture above). The equipment in the background, the green cylinder, is a secret part of Atlas Copco's research work, a so called Spluriser. Because of this, you should forget it immediately.
Test Run
The test was conducted in such a manner that the DUT (Device Under Test) was mounted as vibration-free as possible in the test equipment, the personnel left the room, the room was hermetically sealed, protective clothing was donned, and we took up a safe position at the observation window.
The rotational speed was slowly increased from zero (ramping) towards 30,000 rpm and the operational parameters were recorded at the point of breaking.
The disc manufacturer, speed at destruction, power loss, temperature etc., were carefully recorded and became the basis of the "Table of Result", in Appendix A.
This was repeated for all eleven DUTs. It is worth noting that we increased the speed manually in the beginning, but later changed and let the explosion-control electronics increase the speed (direct ramping). The latter resulted in a somewhat increased durability of the DUT, usually a few thousand rpms.
Also note that the whining of the motor, the vibrations in the walls and the roaring of the CD-ROM disc, not unlike the sound of a crashing jet aeroplane, was impressive, and of course drew great interest from the staff at neighbouring laboratories.
When the disc fractured, there was a sharp bang and the test chamber was filled with shimmering, glittering shrapnel, and our grins were big. We hurried in and mounted the next disc, to be able to shoot again as fast as possible.
G Forces in the Disc
At 30,000 rpm the periphery of the disc is subjected to over 1500 g, and the hub is subjected to a force of 35 N/mm2 on its inner side. It is this force that will ultimately break up the disc.
Kevlar Reinforced CD Record
In our efforts of reaching ever increasing speeds, we tried to reinforce a disc with Kevlar wires. The wire was wound across the disc, as seen in the first picture. As Kevlar needs some pre-tensioning, the disc shows some warping when resting, as seen in the second picture. The warping disappears at increased speeds, though.
Kevlar is the strongest material in existence, many times stronger than unhardened steel and sewing thread. The wire we used, had an ultimate tensile strength of 80 N. As the wire was wound 5 times around the same point on the disc periphery, the wire bundle had a total ultimate tensile strength of 400 N (enough to hang a bicycle in).
It turned out our motor didn't have enough power to spin up the disc enough to explode it in one try, because the Kevlar wires consumed several hundred watts of motor power for aerobreaking.
After an extended period of time (about 20 seconds) at close to 28,000 rpm, the disc blew up with a loud bang anyway, with the wires remaining on the hub, as shown in the picture. It can be clearly seen that the wires remains pointing radially from the hub. The Kevlar wires had been stretched radially and performed as intended. What made the disc explode, was the creepage of the plastic material, i.e. its stretching over time, subjected to the high g forces.
Results
The result surpassed our wildest hopes, sorry: the result was scientifically convincing. The premises and the test equipment also became slightly modified during the testing.
The CD fragments left the disc at such high ejection speed that they deformed the shrapnel protectors, made out of 1.0 mm aluminium. The protectors were dented, torn up, and knocked off their fastening bolts.
One fragment has hit the protector with such force, that the metal has been torn up in an 8 mm rift. It is not probable that the fragment passed through the crack.
At a pre-test, performed without shrapnel protection, long rifts were torn in the ceiling, as shown in the picture. The speed sensor also had its surface coating ripped off.
Decontamination of the premises was time consuming, and yet it was not possible to recover all the shrapnel. We did remove so much, that there is no longer any great risk of damage to the environment or the climate. The picture shows the nice collection of plastic pieces remaining after the tests.
A close-up of the shrapnel, showing its enormous diversity, and its interesting colour characteristics. The self-tapping screw visible in the middle left, BZX4x12, galvanised steel, is not attributable to our experiment, but has to be ascribed to the extremely carefully, close to exaggeration, carried out decontamination process.
This final picture, shows the fragments in detail. You may study the breakage surfaces and the individual chips. It should be noted that we still haven't finished the scanning electron microscopic studies, so probably all details haven't been revealed yet. At the bottom right, the text "Corel Corporation" is visible.
Suggestions for Methods of Achieving Higher Data Transfer Rates
It is obvious the CD-ROM's are too brittle for rotational speeds over 23,000 rpm. As the speed is such a limiting factor for increasing the data transfer rate from CD-ROM records, other resolutions must be sought. Either the method of readout, or the medium should be changed.
Multiple Tracks
As most files take up more than one track on the record, it would be desirable to try to read more than one track at a time. Suppose you exchange today's reading phototransistor for a CCD array and read, for example 100 tracks at a time. This would increase the transfer speed 100 times, without the need for increasing rotational speed.
Multiple Reading Heads
For multi-user applications it would be feasible to use three or four reading heads together on the same CD record. This would need mounting four reading mechanisms at 90 degrees angle to each other in the same drive. If the same user was using all the four heads, intelligent caching could be used for increasing the transfer rate. Otherwise, four users would be able to read at four different places on the disc at the same time, with the four users experiencing increased reading speed, compared to the case of using one reading head and time-shared access.
Kevlar Lamination
Lamination with Kevlar fabric is an obvious solution. Not only does this render the disc capable of standing 20,000 rpm, but as the Kevlar fabric will have to be sandwiched between two CD records, preferably glued label-to-label, the record will be double-sided, thus having double the storage capacity of today's records, about 1.3 GB. Because it is possible to read both sides at the same time, readout speed is again doubled. The motor power required, some 300 watts, would impose a rather heavy loading on the computer's power supply, though.
Caching
It would be possible to build a hard disk into the CD-ROM drive. When a record is inserted into the drive, it will automatically start to read information onto the hard disk. All user accesses will go to the hard disk and all the advantages of the hard disk will be available, such as access times of less than 10 ms, and latency times in the order of 3-4 ms. Hard disks with the capacity to store an entire CD-ROM, today cost no more than a standard quality CD-ROM drive, so a cached CD-ROM drive would command a price of no more than 1.7-1.8 times the price of an un-cached one. This is no great hindrance for the ordinary consumer.
Safety Recommendations
The committee wishes, after finishing its work, to suggest the following safety precautions.
Safe distance to a CD-ROM drive with spin ratio 64x CLV should be no less than 5 metres (15 ft.).
All work with CD-ROM units should require safety goggles and protective clothing be worn.
CD-ROM drives of the 64x CLV class and higher, should be provided with shrapnel protection of no less than 3 mm aluminium or 1 mm steel.
To avoid operator inhalation of CD-ROM particles, CD-ROM drives should be provided with a dust suction fan with suitable filter, or have the fan duct connected directly to the outside air.
In addition to the laser light warning label, CD drives should be affixed with another label warning against the hazard of shrapnel, such as the one below:
Summary
CD-ROM drives with spin factors higher than 64x are impossible to build, as most records reach their ultimate strength limit at this speed. Instead, other solutions have to be sought, such as using several read heads, reading several tracks at at a time, or the like.
The general recommendation is that you never stand close to a 64x drive, if it isn't mounted in an explosion proof enclosure. You could have your stomach perforated.
Appendices
Appendix A. Table of Results
No.
Type
wd
vp
vp%c
P24000
Notes
1
CD-R, Maxell
27000
170
49.87
86
Type CD-R74XL
2
CD-ROM, CorelDRAW 6
24000
151
44.33
86
3
CD-ROM, CorelDRAW 6
23000
144
42.48
86
Heavily maltreated with a blunt object
4
CD-ROM, CorelDRAW 8
25020
157
46.21
86
5
CD-R, Maxell
25020
157
46.21
86
Type CD-R74XL
6
CD-ROM, Ventura 7
26200
165
48.39
86
From this record on, direct ramping was employed
7
CD-ROM, WP Suite 8
27400
172
50.61
86
Lots of printing on
8
CD-ROM, CorelDRAW 6
27900
175
51.53
330
Kevlar reinforced. Blew up after long time
9
CD-ROM, Ventura 7
27900
175
51.53
86
10
CD-ROM, CorelDRAW 6
27900
175
51.53
86
11
CD-ROM, WP Suite 8
28600
180
52.83
86
Lots of printing on
wd: Rotational Speed of Destruction (rpm)
vp: Peripheral Speed at Rotational Speed of Destruction (m/s)
vp%c: Peripheral Speed as a Percentage of the Speed of Sound (% of 340 m/s)
P24000: Power consumption of the record at 24,000 rpm (W)
Comment: It is obvious that a higher wd can be achieved by direct ramping of the speed than manual ramping, as the manual ramping takes longer time. The creepage of the plastic material plays a major part in how long it takes before the disc explodes.
Appendix B. Charts
Chart 1. Rotational Speed of Destruction (wd)
Comments: The Kevlar reinforced record, no. 8., would have reached 30,000 rpm, but our motor didn't make it. Disc no. 3 was impact tested with a heavy tool, which is why it cracked so early.
Chart 2. Peripheral Speed at Rotational Speed of Destruction (vp)
Comment: None of the discs reached more than 180 m/s, but on the other hand that's about 650 km/h, the cruising speed of a jet airliner.
Chart 3. Peripheral Speed as a Percentage of the Speed of Sound (vp%c)
Comment: With our 180 m/s maximum, we were far from the sound barrier. The speed of sound is 340 m/s. Hence, a CD-ROM cannot make sonic booms, at least not rotation-wise.
Chart 4. Power Dissipation of the Record at 24,000 rpm (P24000)
Comment: At these speeds a CD-ROM takes about 80-90 W. It does heat up a lot. The Kevlar reinforced record, no. 8, used a lot more power because of the aerobreaking effect of all the Kevlar wires. But it looked much groovier.
Appendix C. Glossary
CLV: Constant Linear Velocity, or constant data transfer speed, meaning that the record is always rotated with such a speed that the readout speed is constant, irrespective of which track is read.
CAV: Constant Angular Velocity, meaning that the record is rotated at constant speed, making the readout speed higher on an outer track than on an inner track. Something to be avoided.
Spin factor: Typeless constant indicating the number of times the CD drive in question rotates faster than an audio CD. Designation: x. An audio player is 1x, meaning 530 rpm when reading an inner track, and 200 rpm reading an outer track. CLV is employed.
First off, why doesn't Bill Gates mention the LGPL?
>>So, $200 for WinXP is 4% the price of a $500 PC. Great math there Bill.
LOL. One of your other respondents says PC manufacturers don't pay retail... I wonder then why the off the shelf copy costs so much if the OEM version is like $20?
>>That's great, you use the API's, don't worry about the fact you've just tied yourself into only one vendor that can ever fix the API, or know what it *really* does...
Yes, Bill is totally assuming that the APIs themselves are 100% open, which of course is NOT the case with Windows APIs.
In closing, I'd just like to say that I hope there were some smart people in the audience and not just people who came to hear Bill Gates' jokes (laughter). Bill's company is under investigation for ANTI-TRUST violations... and yet his opinions are still solicited. Think about the meaning - anti...trust. His company broke the trust. A friend like this might be called a Back Stabber. How would you treat a friend like that?
I think the government should stop listening to Microsoft until the antitrust suits against them have completed and remedies have been applied.
Why on God's Green Earth is the government still soliciting Microsoft's opinion on what is right and wrong? Microsoft is obviously guilty of many charges and for some reason has even escaped the charge of purgery. Makes you wonder if the gov't even cares that Microsoft has broken the law so many times. Maybe it's all a show.
cuntcasket... now that's a new one.
Anyway, if everyone goes out and buys a processor from a company with a reject CEO, why would the board of directors ever let the CEO go? The CEO is supposed to reflect the opinions of the company, and since I strongly disagree...
Honestly, what he's been quoted as saying sounds exactly like a Microsoft line. I wouldn't be surprised if the people who write Bill's speeches wrote this one as well.
You've got a point there... so I'm checking out Transmeta processors now. Any problem with them? ;)
UNBELIEVABLE... seriously, I was going to buy my first AMD processor in the next couple of weeks. It's obvious that they're in Microsoft's pockets now... guess it'll be an Intel for me, thank you.
Their prices will be dropping soon anyway.
I used to live in Canada. They threatened to do this 2-3 years ago as I recall... but for some reason did not.
Finally, the insanity of it all has come to light. What a shame.
I also remember that when cigarettes when to $8 a pack, smuggling skyrocketed, and the government backed off so they were back down to the $4 range (don't know what they are now up there). I hope the same thing happens with CDR's, etc...
I bet they're kicking their asses now for not taking all the land they discovered. I wonder why they didn't start colonizing? Maybe at the time it wasn't feasible...?
With Pacific Bell (and probably most other providers), they will divvy up the days of downtime you had, then subtract the pro-rated amount off your bill. You won't get a free month with these guys, trust me. You don't get a red cent for the hours you waste on the phone with tech support, and you also don't get anything for waiting hours and hours for a technician to arrive. That's not even getting into the lost productivity...
Someone correct me if I'm wrong here...
7,400,000,000 miles = 119,066,000,000 kilometers
speed of light = 299,792,458 meters per second
which equals 299,792.458 kilometers per second
119,066,000,000 / 299,792.458
approximately equals 397,161 seconds
which equals 110.3225 hours
So, if the Pioneer spacecraft were going the speed of light from the beginning, it would have only taken it less than 5 days to get where it is today, 30 years later. Wow! Anyone getting close to inventing speed of light travel yet?
Parent and parent's parent are the best I've heard summing up creativity. Great posts.
:)
I remember working with lego, meccano, capsula, playdoh, a plastic building kit (can't remember the name), armatron, and working with wood, tools, bicycles, pipes, cardboard, you name it. And of course, taking things apart and usually getting them back together (with a few spare pieces of course).
This is a part of my life I will always remember and, even though I'm into computers today, I will try and pass the above creativity down to my kids someday. I'm very happy I had the chance to do these things.
Someone please tell me how Gnome can be killed.
It is an open source project with AFAIK, to date, no patented code in it. So, if I decide to take a CVS snapshot today and maintain a new branch of it, there should be nothing stopping me and no way to "kill it".