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A Disc That Will Hold a Bigger Byte of Data
http://www.nytimes.com/2003/01/23/technology/circuits/23askk.html
Q & A

A Disc That Will Hold a Bigger Byte of Data

   Q . I have heard that new DVD's are being developed that can hold more
   than 20 gigabytes of data. How is that accomplished, and when will
   these discs be on the market?

   A. A new type of high-capacity disc similar in physical size to DVD's
   and compact discs is being developed and is expected to hold 27 or 54
   gigabytes of data. It is called a Blu-ray disc, and the technical
   standard for it is a joint effort by major companies, among them
   Philips, [71]Hitachi, [72]Sony, Pioneer, Samsung, Sharp and
   Panasonic's parent company, Matsushita.

   A disc in the DVD format can currently hold 4.7 gigabytes of data.
   Unlike DVD technology, which uses red lasers to etch data onto the
   disc, the Blu-ray disc technology uses a blue-violet laser to record
   information. The blue-violet laser has a shorter wavelength than the
   red lasers do, and with its smaller area of focus, it can etch more
   data into the same amount of space on a disc.

   With their large storage capacity, recording and storing
   high-definition television programs is one of the uses expected for
   Blu-ray discs, because HDTV contains vastly more video data than
   standard television does. With 27 gigabytes, Blu-ray can record over
   two hours of digital high-definition video and more than 13 hours of
   standard TV programming. The technology is still in the licensing and
   development stage, and the first Blu-ray recorders from major
   manufacturers are expected sometime within the next year or two.
   Affordable consumer players and recorders are probably still a few
   years away.

   Q. I want to edit digital camcorder footage on my home computer, but I
   have heard that video data takes up a huge amount of space. I am
   concerned that I do not have enough hard drive space. How much do I
   need to store digital video?

   A. Compared with word-processing documents and other common types of
   computer files, video from a camcorder does take up a large amount of
   hard-drive space. A rule of thumb is that you need one gigabyte of
   space for every four minutes of uncompressed video imported directly
   from the camcorder.

   The boom in digital video editing is perhaps one reason that
   hard-drive capacities in many new computers are often available in 60,
   80 and 120 gigabytes, compared with only 10 or 20 gigabytes a few
   years ago. If your current hard drive is not large enough for your
   project, adding an external hard drive can give you more space. For
   example, several companies make external 80-gigabyte hard drives that
   cost less than $200.

   Q. I have often heard the warning that improperly editing the Windows
   Registry file can disable Windows itself and render the computer
   incapable of starting up. What is in the Registry that makes it so
   vital?

   A. The Registry, a comprehensive database kept by the Windows
   operating system, stores a lot of information about the computer. It
   holds information about all the hardware used by the PC and
   instructions to itself about which hardware drivers to use with each
   device. It also records information about all the software installed
   on the computer, file associations, user preferences and the data that
   the Windows system needs to run the PC.

   Although Windows allows you to edit the Registry with the Regedit .exe
   program, it is generally not advisable to do so unless you know
   exactly what you are doing (or are comfortable with reinstalling
   Windows and all of your software). Mistakes in the Registry's record
   can send Windows into a state of confusion and leave it unable to
   start properly.

   Windows 98 was the first version of the system to include a tool for
   rescuing the Registry if a bad version of it is found during the
   computer's start-up process. The Windows Registry Checker Tool creates
   backup copies of the working Registry file, and if a bad version is
   found, it can restore the previous version to allow Windows to start
   up. You can also configure the Windows Registry Checker, for example,
   to specify the number of backup copies to make and where to store
   them, by going to the Start menu, selecting Run and typing
   scanregw.exe.

   J. D. BIERSDORFER