Tape Drives

CD ROMs

Data on CD-ROM disks can be read using a CD drive. Table 10.2 on page 170 lists the locations of CD-ROM drives. Most of the commands you use when working with files and directories also apply to a CD-ROM (commands such as DIRECTORY, TYPE, and COPY). Because CD-ROM disks are read-only devices, you can not delete or write information to them.

Like tape drives, a CD-ROM drive must be allocated and mounted before you can use it, and then dismounted and released when you are finished with it. The sequence of commands used in working with CD-ROM disks would be:

  1. Allocate the drive using the ALLOCATE command.

  2. Mount the disk by putting the CD-ROM disk into the drive and then issuing the MOUNT command, for example:

   $ MOUNT device label
  1. Use the disk with normal file system commands. For example:

   $ DIR device:[00000]
  1. Dismount the drive using the DISMOUNT command and remove your CD-ROM disk from the drive.

  2. Release the drive using the DEALLOCATE command.

ISO 9660 CD-ROM Disks

Some CD-ROMs are written in a different media format called ISO 9660 (International Standards Organization, 1988 Information Processing, Volume and File Structure of CD-ROM for Information Interchange).

ISO 9660 CD-ROMs require a different command for the mounting step when you are using a VAX system--the CD_MOUNT command. Use a command like this: 

$ CD_MOUNT/OVER=ID/MEDIA=CDROM/UNDEFINED_FAT=(STREAM:65535)-
  device_name CDDISK
If you are using an Alpha system, you would use the following MOUNT command to mount the CD-ROM: 

$ MOUNT/OVER=ID/MEDIA=CDROM/UNDEFINED_FAT=(STREAM:65535)-
  device_name label
ISO 9660 CD-ROM Disks

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