What is CD-ROM/XA?
CD-ROM/XA is an extension to the Yellow Book Standard. A track on a CD-ROM/XA disc can contain computer data, compressed audio data, and video/picture data. Many CD-ROM drives do not support CD-ROM/XA. CD-ROM/XA extends CD-ROM by adding some of the CD-I disc features (such as using Mode 2 tracks with interleaved compressed-audio and other data). Thus CD-ROM/XA (eXtended Architecture) is often called the "Bridge" format between CD-ROM and CD-I... though the relationship is mostly the sector types. CD-ROM/XA applications still require specific code for each target platform.
CDROM-XA specifies a `bridge format' so that a CDROM-XA disc can be read on a CD-I player as well as on a PC under MSCDEX (provided that you use a conforming (.SYS) driver. On a normal yellow-book CDROM, a data track contains only mode-1 data sectors. On a CDROM-XA, a (the) data track contains only mode-2 data sectors. A mode-2 sector can be of two formats, form-1 and form-2. A form-1 sector contains 2048 bytes of user data, together with EDC and ECC bytes. A form-2 sector contains 2324 bytes of raw data (e.g. ADPCM audio or video data). If the device driver delivers 2048 bytes of data when MSCDEX asks for it, regardless whether the sector is mode-1 or mode-2/form-1, the PC is CDROM-XA compatible.
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For Information, contact Ken Cheney |
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