Berkeley CSUA MOTD:Entry 28723
Berkeley CSUA MOTD
2018/06/23 [General] UID:1000 Activity:popular

2003/6/13 [Finance/Banking, Computer/HW/Drives] UID:28723 Activity:nil
6/12    Extreme CDs:
2018/06/23 [General] UID:1000 Activity:popular

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2006/8/12-15 [Finance/Banking, Computer/HW/Drives] UID:43982 Activity:nil
8/11    Aside from physically breaking a CD, what's the easiest way to make
        it permanently unreadable?
        \_ If you have a secure shredder service, they usually handle CDs as
        \_ Get a screwdriver, scratch the top of the CD.  It's not that much
           more work than writing with a pen.  Remember, data on CD is near
2005/2/3-5 [Computer/HW/Memory, Computer/HW/Drives] UID:36055 Activity:moderate
2/3     So, I'm really confused about this notion of computer science
        metrics where everything's kind of 2^n, but sometimes not. For
        example, if I have a 4 GIG hard drive, does that mean I have
        exactly 2^32 bytes of space? Does that translate to 4000000000
        bytes, or some number that's close to it? How about megahertz?
        Say I have a 2.5GHz computer, does it run at exactly 2500000
2004/9/1 [Computer/HW/Drives] UID:33272 Activity:high
9/1     Securely destroy your CD/DVDs:
        \_ Don't CDs often have stuff you aren't supposed to breathe in
        \_ nuke it in the microwave.
        \_ Do people really need this?  If I just break a CD in half, can
2000/8/28-29 [Computer/HW/Drives] UID:19115 Activity:kinda low
8/28    I copied an audio CD with a CD drive on a PC, and the duplicate CD can
        only play in a regular CD player but not in a DVD player.  The DVD
        player doesn't recognize the CD.  Is this a common problem?  (I have
        consent from the author of the CD to make copies.)  -- yuen
        \_ Yes, many DVD players do not support CD-R/RWs. I believe only
           Toshiba or Sony has comprehensive support of all disc formats
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The Dremel was switched on and the rotational velocity was gradually increased to its maximum, at which point the CD hummed and whined in a very menacing manner. Mildly disappointed that it had not exploded, I realized that it wanted out; It peeled out a bit in front of me and proceeded to make its way to the door at a very high speed. On contacting the closed door, the CD did a most unexpected thing: it first bounced back a few inches, and then, when it hit the door again, it jumped straight up the door and struck the ceiling, exploding into thousands of fragments which rained down on the entire room. This first experiment was unfortunately not videoed, but it served to get everyone in the room to put glasses on and cower away behind pieces of furniture, whilst people in the hall corridor quickly made their way to my door to ask what was going on. At those speeds the CD is storing over 150joules of energy. Conversely, if the CD was to explode at that velocity, the pieces would escape at a similar speed. Although a Dremel tool does not have the required power to sustain its maximum RPM with a load as big as a CD-Rom, the CDs did go very fast; Results and Discussion: 11 Click picture to watch the full CD experiment video. Click picture to watch the full CD experiment video (1m28, 8mb), or check out the best exploding CD 12 here. Several companies have made the maximum speed CD-Writing standard 48x ( 13 see article) instead of 52X or higher due to the fact that at 52x the CD is spinning at 10 000RPM and several CDs have been known to explode at those speeds, destroying the drive and some times sending pieces out from the CD tray. The fastest drivers on the market today employ multiple reading heads to achieve twice, or even 3 times the read rate for the same RPM, so until DVDs take over CD drives still have a lot of room for improvements. Just in case anyone is wondering: if a CD really was to spin at 35000RPM in the drive, it would be possible to read it at 175X :) Update: Matt e-mailed me the following warning: You'd think a CD could handle 52x, right? I tried playing GranTurismo on ePSXe, and it exploded right in the drive! Shockingly, we all got hit with shards of CD (which were slowed down when they blew the faceplate off my CDROM drive), but the computer was fine, and the CDROM still works today, after dismantling it and removing all the shattered plastic. Removing any material from this site for display without consent from its author consists in an infringement of international copyright laws and can result in fines up to $50000 per infringement, plus legal costs.