SIGCAT
A CD-ROM is a pre-pressed compact disc that contains data accessible to,
but not writable by,a computer for data storage and music playback,
the 1985“Yellow Book”standard developed by Sony and Philips adapted
the format to hold any form of binary data.
CD-ROMs are popularly used to distribute computer software,
including games and multimedia applications,though any data can be stored
(up to the capacity limit of a disc).Some CDs hold both computer data and audio
with the latter capable of being played on a CD player,while data
(such as software or digital video)is only usable on a computer
(such as ISO 9660 format PC CD-ROMs).These are dubbed enhanced CDs.
There are multiple formats used for data stored on compact discs,known collectively
as the Rainbow Books.These include the original Red Book standards for CD audio, White Book and Yellow Book CD-ROM.
The ECMA-130 standard, which gives a thorough description of the physics and physical layer of the CD-ROM,
inclusive of cross-interleaved Reed-Solomon coding(CIRC) and eight-to-fourteen modulation (EFM), can be downloaded from ECMA.
ISO 9660 defines the standard file system of a CD-ROM,even though it is because of be replaced by ISO 13490(which also supports CD-R and multi-session).
UDF extends ISO 13346(which was created for non-sequential write-once and
re-writeable discs such as CD-R and CD-RW)to support read-only and re-writeable media and was first instituted for DVD.The bootable CD specification,to make a
CD emulate a hard disk or floppy,is called El Torito.
CD-ROM drives are rated with a speed factor relative to music CDs
(1×or 1-speed which gives a data transfer rate of 150 KiB/s).
12× drives were usual beginning in early 1997. Above 12×speed,
there are dificulties with vibration and heat.
Constant angular velocity (CAV)drives give speeds up to 30×at the outer edge of
the disc with the same rotational speed as a standard constant linear velocity(CLV)12×,or 32×with a slight increase. because of the nature of CAV
(linear speed at the inner edge is still only 12×,increasing smoothly in-between)
the actual throughput increase is fewer than 30/12 - in fact,harshly 20×average for a completely full disc, and even less for a partially filled one.
The original SIGCAT(Special Interest Group on CD Applications and Technology)was a Special Interest Group locateded in 1986 by Jerry McFaul.
It became the world's hugest CD-ROM users'group,with over 11,000 members in 75 countries. SIGCAT held annual conferences until 1999.
Around 2002, SIGCAT was absorbed into the DVD Association (DVDA), an organization that had sprung from the CD Interactive Association (CDIA). The DVDA continues to hold conferences and other events,and it is now known as International Digital Media Alliance
