资料来源 : Free On-Line Dictionary of Computing

Digital Versatile Disc
     
         (DVD, formerly "Digital Video Disc") An optical
        storage medium with improved capacity and bandwidth compared
        with the {Compact Disc}.  DVD, like CD, was initally marketed
        for entertainment and later for computer users.  [When was it
        first available?]
     
        A DVD can hold a full-length film with up to 133 minutes of
        high quality video, in {MPEG-2} format, and audio.
     
        The first DVD drives for computers were read-only drives
        ("DVD-ROM").  These provide over seven times the storage
        capacity of CD-ROM (4.7 GBytes).  DVD-ROM drives read existing
        {CD-ROM}s and music CDs and are compatible with installed
        sound and video boards.  Additionally, the DVD-ROM drive can
        read DVD films using an advanced (MPEG-2) video board,
        required to decode the high resolution video format.
     
        The first drives, using a single-layer disc of 4.7GB, were
        expected to be available during the second half of 1996 from
        {Toshiba}, {Philips}, {Sony}, {Hitachi} and others.  In 1997,
        dual-layer discs were expected to increase the disc capacity
        to 8.5 GB.  Double-sided, dual-layer discs will eventually
        increase the capacity to 17 GB.
     
        Write-once DVD-R ("recordable") drives record a 3.9GB DVD-R
        disc that can be read on a DVD-ROM drive.  The first DVD-R
        drive was expected by mid 1997.
     
        By the end of 1997, the rewritable DVD-RAM (by false analogy
        with {random access memory}) drive was expected to become
        available.  DVD-RAM drives read and write to a 2.6 GB DVD-RAM
        disc, read and write-once to a 3.9GB DVD-R disc, and read a
        4.7 GB or 8.5 GB DVD-ROM.  Also, it was expected that a
        DVD-RAM disc would be readable on both the DVD-R and DVD-ROM
        drives.
     
        {Background (http://www.tacmar.com/dvd_background.htm)}.  {RCA
        home (http://www.imagematrix.com/DVD/home.html)}.
        {(http://www.zdnet.com/products/special/current/dvd.html)}.
        {(http://www.zdnet.com/products/special/current/dvdsum.html)}.
     
        [Did this happen as predicted?  Current state?]
     
        (1999-07-08)