Re: MD: magnetic damage
[EMAIL PROTECTED] wrote: Correct me if I'm wrong, but isn't an MD encoded optically? Maybe I'm just mistaken, but there better be a damn good reason for having a Class 1 Laser product sticker on my deck... Yes and No. MD is magneto-optical. The material of the disc is a special material that has a special carecteristic. The atoms can be alligned into a certain direction when the temporature is higher than 160 degrees Celcius. In order to heat the material a laser is used. In order to change the direction of the material, a magnet is used. Atoms reflect more or less light depending on the direction they have. Thus you can read the direction (thus the information) using a laser. Cheers, Ralph - changing directions without magnetics or laser. -- === Ralph SmeetsFunctional Verification Centre Of Competence - CMG Voice: (+33) (0)4 76 58 44 46 STMicroelectronics Fax:(+33) (0)4 76 58 40 11 5, chem de la Dhuy Mobile: (+33) (0)6 82 66 62 70 38240 MEYLAN E-Mail: [EMAIL PROTECTED] FRANCE === "For many years, mankind lived just like the animals. And then something happened that unleashed the powers of our imagination: We learned to talk." -- Stephen Hawking, later used by Pink Floyd -- === - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: magnetic damage
"Brett Tyre" [EMAIL PROTECTED] wrote: So really, an MD is not a small compact disc, it is a shrunken version of the ancient and obscure magnoptical computer disks... MO (magneto-optical) disks are alive and well. They are widely used for backup and archiving solutions because they are still the most reliable medium out there (debatable with CDR, but MO disks are a lot more flexible). I use a Fujitsu SCSI MO drive that I bought new last year. There are now FireWire versions of the 1.3GB and 640MB MO drives. Less popular than a Zip? Yes. Ancient and obscure? Hardly ;-) - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
RE: MD: magnetic damage
I was thinking about a damage in the magnetical orientation and not in the inner structure of the MD, but this is also a possibility. -Original Message- From: Stainless Steel Rat [mailto:[EMAIL PROTECTED]] Sent: Wednesday, April 19, 2000 3:55 AM Subject: Re: MD: magnetic damage * "Black_Angel" [EMAIL PROTECTED] on Tue, 18 Apr 2000 | Teorically it's impossible to damage a MD only with a magnetic field. No, it is impossible to _erase_ an MD with a magnetic field. But a sufficiently powerful EM field could warp or crack the metallic layer, rendering the disc unusable. -- Rat [EMAIL PROTECTED]\ Ingredients of Happy Fun Ball include an Minion of Nathan - Nathan says Hi! \ unknown glowing substance which fell to PGP Key: at a key server near you! \ Earth, presumably from outer space. - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
RE: MD: magnetic damage
Herro, They may be obscure and ancient, but MO discs are brilliant. I bought a 230MB Fujitsu M2512A drive six years ago for a printing business I ran. The drive is still going strong, the discs seem indestructible and it gives good performance, even through my old ISA SCSI card. It certainly beats Zip, especially for reliability. And the discs look exactly like a MD on steroids - splendid. Cya Alan -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Brett Tyre Sent: 19 April 2000 04:07 To: [EMAIL PROTECTED] Subject: Re: MD: magnetic damage So really, an MD is not a small compact disc, it is a shrunken version of the ancient and obscure magnoptical computer disks... -- NP: Brett Tyre [EMAIL PROTECTED] [EMAIL PROTECTED] London Drugs, Comp. Dept. "My 98 is fly, I don't drive no junk" -Chuck D - Original Message - From: "Sean Harding" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Tuesday, April 18, 2000 7:51 PM Subject: Re: MD: magnetic damage On Tue Apr 18 at 07:36:29 PM, Brett Tyre wrote: Correct me if I'm wrong, but isn't an MD encoded optically? Maybe I'm just The recordables are magneto-optical. sean -- Sean Harding [EMAIL PROTECTED]|"Don't spread discontent, don't http://www.dogcow.org/sean/ | spread the lies." | --Natalie Merchant - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED] - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED] - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: magnetic damage
On Tue Apr 18 at 08:07:22 PM, Brett Tyre wrote: So really, an MD is not a small compact disc, it is a shrunken version of the ancient and obscure magnoptical computer disks... Optical is older than MO...If you're more concerned with where else the technology has been used than how it works in its current implementation, then perhaps MD isn't for you. But those of us who just care how well it works have no problem with it. sean -- Sean Harding [EMAIL PROTECTED]|"I'm consuming my life http://www.dogcow.org/sean/ | and it tastes so good." | --The Nields - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: magnetic damage
Hey, I'm impressed with MD. It works great, and its much more convienient than CD-R. -- NP: Brett Tyre [EMAIL PROTECTED] [EMAIL PROTECTED] London Drugs, Comp. Dept. "My 98 is fly, I don't drive no junk" -Chuck D - Original Message - From: "Sean Harding" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Wednesday, April 19, 2000 4:36 PM Subject: Re: MD: magnetic damage On Tue Apr 18 at 08:07:22 PM, Brett Tyre wrote: So really, an MD is not a small compact disc, it is a shrunken version of the ancient and obscure magnoptical computer disks... Optical is older than MO...If you're more concerned with where else the technology has been used than how it works in its current implementation, then perhaps MD isn't for you. But those of us who just care how well it works have no problem with it. sean -- Sean Harding [EMAIL PROTECTED]|"I'm consuming my life http://www.dogcow.org/sean/ | and it tastes so good." | --The Nields - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED] - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: magnetic damage
On Mon, 17 Apr 2000 [EMAIL PROTECTED] wrote: Hi, since mds are recorded w/ magnetic signals, can airport metal detectors or x ray machines cause damage to the info on md's? Well, MD recording is MO, (Magneto Optical), this means that to be magnetized, i.e. oriented (North/South) the minimum magnetic undivisible particle that composes the MO storage medium, called domains, must be first heated to Currie temperature with a laser. Once oriented, they cool, and cannot be oriented until they're heated again. So I'd bet you can put a dynamo magnet over a MD disk if you like and it will remain intact. Beware that depending the kind of plane, the use of MD could be forbidden on the whole flight, or just on the shuttle (sorry, don't have a dictionary handy :) and landing phases. At least in Spain (Iberia), and with DC-10 or 727 planes, MD use is absolutely forbidden during the whole flight. greets, *---(*)---**-- Francisco J. Montilla System Network administrator [EMAIL PROTECTED] irc: pukkaSevilleSpain INSFLUG (LiNUX) Coordinator: www.insflug.org - ftp.insflug.org - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: magnetic damage
Francisco Jose Montilla wrote: So I'd bet you can put a dynamo magnet over a MD disk if you like and it will remain intact. I don't know what a dynamo magnet is, but I was able to corrupt data on an MD using a ceramic magnet out of a microwave oven's magnetron. -- Shawn Lin http://www2.cybercities.com/g/gmwbodycars/ _ NetZero - Defenders of the Free World Click here for FREE Internet Access and Email http://www.netzero.net/download/index.html - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: magnetic damage
. I don't know what a dynamo magnet is, but I was able to corrupt data on an MD using a ceramic magnet out of a microwave oven's magnetron. Yeah, but a magnetron is like, a powerful magnet. Thats where all the weight comes from in those things. You basically have the magnet around a vaccum tube which produces a strong magnetic field then creates a high fequency pulse (the microwave radation). But, yeah, blasting MD's with a wave from a magnatron isn't good either (took an old microwave apart). -J.R YOU'RE PAYING TOO MUCH FOR THE INTERNET! Juno now offers FREE Internet Access! Try it today - there's no risk! For your FREE software, visit: http://dl.www.juno.com/get/tagj. - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: magnetic damage
[EMAIL PROTECTED] wrote: Francisco Jose Montilla wrote: So I'd bet you can put a dynamo magnet over a MD disk if you like and it will remain intact. I don't know what a dynamo magnet is, but I was able to corrupt data on an MD using a ceramic magnet out of a microwave oven's magnetron. -- Shawn Lin http://www2.cybercities.com/g/gmwbodycars/ Well, I don't know for Spain, but here in our frog-land, The Netherlands, a dynamo is a small alternator that generates current. It's normaly found on bicicles. Cheers, Ralph -- === Ralph SmeetsFunctional Verification Centre Of Competence - CMG Voice: (+33) (0)4 76 58 44 46 STMicroelectronics Fax:(+33) (0)4 76 58 40 11 5, chem de la Dhuy Mobile: (+33) (0)6 82 66 62 70 38240 MEYLAN E-Mail: [EMAIL PROTECTED] FRANCE === "For many years, mankind lived just like the animals. And then something happened that unleashed the powers of our imagination: We learned to talk." -- Stephen Hawking, later used by Pink Floyd -- === - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: magnetic damage
From: "Shawn R. Lin" [EMAIL PROTECTED] Francisco Jose Montilla wrote: So I'd bet you can put a dynamo magnet over a MD disk if you like and it will remain intact. I don't know what a dynamo magnet is, but I was able to corrupt data on an MD using a ceramic magnet out of a microwave oven's magnetron. You most definitely could corrupt the magnetic info without heat-- on TV recently a science program featured an electromagnet that could magnetise *Anything*, they even magnetically levitated a rat (which was unharmed). I don't think such powerful magnetic fields are commonly found though, did I mention it took about 1MW of power to magnetise the space inside the short four or so inch diameter tube space! They mentioned they could levitate a human ie. simulate weightlessness but the magnet would draw over 100MW thereby requiring a more or less dedicated power station, cost maybe a few hundred million dollars or more, and it would be cheaper to use the Space Shuttle anyway for weightlessness! Wow!!! ___ ___ | || | | o || o | | |Gareth Bell - [EMAIL PROTECTED] | | | o || o | | | _ _ | | | o | | __ \ _ _ _ / ___| _ | O | | | | |__| )| __)(_)| _ \| __)| _ \ | | _ ( \|__ / | | | o | | ___/ | / | ||_| | || | | |_| | | | \ || _ | / _/ | O | | | | | | | | ||_| | || |__ | / | |_| || |_| |/ /__ | | | o | |_| |_| |_||_| |_||)|_) \_/|_||| | O | | || | | o || o | | | ICQ: 36892193 http://website.lineone.net/~princegaz/| | | o || o | | |"An it harm none, do what thou wilt"| | | o || o | |___||___| - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
RE: MD: magnetic damage
I don't know what a dynamo magnet is, but I was able to corrupt data on an MD using a ceramic magnet out of a microwave oven's magnetron. Teorically it's impossible to damage a MD only with a magnetic field. But the magnetic field might generate electromagnetic waves and heat the MD, and then damage it. - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: magnetic damage
* "Black_Angel" [EMAIL PROTECTED] on Tue, 18 Apr 2000 | Teorically it's impossible to damage a MD only with a magnetic field. No, it is impossible to _erase_ an MD with a magnetic field. But a sufficiently powerful EM field could warp or crack the metallic layer, rendering the disc unusable. -- Rat [EMAIL PROTECTED]\ Ingredients of Happy Fun Ball include an Minion of Nathan - Nathan says Hi! \ unknown glowing substance which fell to PGP Key: at a key server near you! \ Earth, presumably from outer space. - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: magnetic damage
Correct me if I'm wrong, but isn't an MD encoded optically? Maybe I'm just mistaken, but there better be a damn good reason for having a Class 1 Laser product sticker on my deck... -- NP: Kox Box -Electronic Brainwash Brett Tyre [EMAIL PROTECTED] [EMAIL PROTECTED] London Drugs, Comp. Dept. "My 98 is fly, I don't drive no junk" -Chuck D - Original Message - From: "Stainless Steel Rat" [EMAIL PROTECTED] To: "MD-L" [EMAIL PROTECTED] Sent: Tuesday, April 18, 2000 6:55 PM Subject: Re: MD: magnetic damage * "Black_Angel" [EMAIL PROTECTED] on Tue, 18 Apr 2000 | Teorically it's impossible to damage a MD only with a magnetic field. No, it is impossible to _erase_ an MD with a magnetic field. But a sufficiently powerful EM field could warp or crack the metallic layer, rendering the disc unusable. -- Rat [EMAIL PROTECTED]\ Ingredients of Happy Fun Ball include an Minion of Nathan - Nathan says Hi! \ unknown glowing substance which fell to PGP Key: at a key server near you! \ Earth, presumably from outer space. - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED] - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: magnetic damage
* "Brett Tyre" [EMAIL PROTECTED] on Tue, 18 Apr 2000 | Correct me if I'm wrong, but isn't an MD encoded optically? Magnetio-optical media like MD is composed of nominally non-magnetic metallic layer bonded to an inert substrate. When recording, the MD laser (the optical part of MO) heats a spot of the metallic layer to the curie point -- the temperature at which a non-magnetic metal acquires magnetic properties. Then the read/write (the magnetic part of MO) head hits that spot with a magnetic field aligned in one direction for "0" and another for "1". When the spot cools it loses its magnetic properties. -- Rat [EMAIL PROTECTED]\ Caution: Happy Fun Ball may suddenly Minion of Nathan - Nathan says Hi! \ accelerate to dangerous speeds. PGP Key: at a key server near you! \ - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
MD: magnetic damage
since mds are recorded w/ magnetic signals, can airport metal detectors or x ray machines cause damage to the info on md's? - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: magnetic damage
* [EMAIL PROTECTED] on Mon, 17 Apr 2000 | since mds are recorded w/ magnetic signals, can airport metal detectors or x | ray machines cause damage to the info on md's? No. -- Rat [EMAIL PROTECTED]\ When not in use, Happy Fun Ball should be Minion of Nathan - Nathan says Hi! \ returned to its special container and PGP Key: at a key server near you! \ kept under refrigeration. - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
