Data Recovery and Digital Storage Glossary

• Cache
  Specialized RAM used to optimize data transfers between system elements with different performance characteristics.
  
  
• CardBus
  High speed 32-bit interface based on the PCI interface. This interface is available on most newer laptop computers as a means for connecting high speed removable cards such as USB, FireWire, Ultra SCSI, Ethernet, and High speed MODEMs. PCMCIA devices can be used in CardBus slots.
  
  
• CD Extra
  Compact Disc Extra (also known as Enhanced CD or CD Plus). A new format for creating interactive music CDs. A CD Extra disc has two sessions. Session one consists of audio tracks. Session two consists of a data track.
  
  
• CD Plus
  See CD Extra.
  
  
• CD Specifications
  The specifications for Compact Disc are contained in several books:
  
  
  • Red Book (1981)
    Original CD-DA standard developed by Sony and Philips.
    
    
  • Yellow Book (1983)
    Specifies parameters for CD-ROMs (does not specify data structure).
    
    
  • Green Book (1986)
    Describes the CD-i format.
    
    
  • Orange Book (1990)
    Describes CD-R and CD-RW format and media.
    
    
  • White Book (1993)
    Describes the Video CD format.
    
    
  • Blue Book (1995)
    Describes the CD Extra standard.
    
    
• CD Text
  CD text is an audio CD format in which up to 5000 characters of disc information (title, artist, song titles, etc.) are written to the disc. This information is displayed when the disc is played back on CD Text-enabled players. The CD-R/RW drive must support this feature. If the CD player does not support CD Text, then this information will not be displayed.
  
  
• CD+G (Karaoke)
  Compact Disc Plus Graphics. A special digital audio disc format that combines a standard CD-DA track with graphic and text subchannels.
  
  
• CD
  Compact Disc. A 12cm disc, made up of polycarbonate substrate, a thin metallic layer, and a lacquer coating, originally used to hold digital audio data (as defined in the Red Book). The compact disc was originally developed by Sony and Philips and was introduced in 1982.
  
  
• CD-DA
  Compact Disc-Digital Audio. A compact disc used to store music. This is the original format used by home and car stereos. CD-DA is defined by the original Red Book Specification released by Sony and Philips in 1981.
  
  
• CD-E
  Compact Disc-Erasable. Allows the user to write, erase, overwrite, and read CD information. This format was replaced by CD-RW.
  
  
• CD-i
  Compact Disc-Interactive. A CD format designed to play interactive multimedia applications on a CD-i player attached to a television. CD-i is described in the Green Book, but is no longer used.
  
  
• CD-R
  Compact Disc-Recordable (One-Off or CD-WO). A recordable compact disc that cannot be erased. CD-R is described in the Orange Book.
  
  
• CD-ROM XA
  Compact Disc-Read Only Memory Extended Architecture. An extension to the Yellow Book specification that was proposed by Sony, Philips, and Microsoft® to enhance the multimedia capabilities of CD-ROMs. XA is also used as a bridge between CD-i players and CD-ROM drives. Kodak's PhotoCD is an example of a CD-ROM XA format.
  
  
• CD-ROM
  Compact Disc-Read Only Memory. A compact disc used to store computer data. Data cannot be written to a CD-ROM. CD-ROMs are defined by the Yellow Book.
  
  
• CD-RW
  Compact Disc-ReWritable. A recordable compact disc that can be erased and rerecorded. CD-RW is defined by part III of the Orange Book.
  
  
• CD-V, CD-Video
  Compact Disc-Video.
  
  
• CD-WO
  Compact Disc-Write Once. See CD-R.
  
  
• Clean Room
  An environmentally controlled dust-free assembly or repair facility in which hard disk drives are assembled or can be opened for internal servicing.
  
  
• CRC
  Short for cyclic redundancy check, a common technique for detecting data transmission errors. Transmitted messages are divided into predetermined lengths that are divided by a fixed divisor. According to the calculation, the remainder number is appended onto and sent with the message. When the message is received, the computer recalculates the remainder and compares it to the transmitted remainder. If the numbers do not match, an error is detected.
  
  
• Cylinder
  A single track location on all the platters making up a hard disk. For example, if a hard disk has four platters, each with 600 tracks, then there will be 600 cylinders, and each cylinder will consist of 8 tracks (assuming that each platter has tracks on both sides).