The compact disc was
launched
in 1982. The first recording released on CD
was Billy Joel's 52nd Street. The CD offered the home
consumer for the first time, high quality digital audio in a robust and
convenient format. The main attractions for the CD was the ability to
play your favorite 'record' more than just a few times without leaving
scratches, noise or damage as the CD was very durable. The consumer
also enjoyed instant access between tracks, the remote control facility
and the small size. The disadvantages at the launch was that few
titles were available and the cost of the CD's was much higher than
that of both vinyl and cassette tape. CD player
prices were also much higher than turntables and cassette decks
back in 1982. But the catalogue of music through the 1980s quickly grew
and player costs quickly reduced. By 1993 just 11 years after launch,
the CD dominated the market
in music sales in the UK and is still the dominant format.
Technical information: The
compact disc is read by a laser which receives a series of digital
pulses from a track of bumps (125 nanometer high) as it follows a
spiral track from the middle
of the disc outwards. The track width is tiny
at just 0.5 microns wide, with 1.6 microns separating the tracks. The
data storage on
a 74 minute CD is so vast (650MB) that the
spiral track if it could be unwrapped would
be almost 5 miles long. The CD initially rotates
in the player at 500 rpm as the laser reads
the inner tracks, the speed slowly decreases
to 200 rpm as the outer tracks are read.
This keeps the data rate constant as the
laser traverses the disc. The digital sample
rate is 44.1 kHz which is more than twice
that of the highest audible frequency ensuring
high resolution digital to analogue conversion. There is no
contact between the laser reader and
the disc during playback ensuring no physical wear of the disc. With
careful handling and storage CDs will last more than a lifetime.
James T Russell invented the
optical audio system and holds a total of 22 patents. The CD was taken
into production by the giant Philips and Sony corporations in 1982.
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First CD released "Billy
Joel" in 1982
The Compact Disk stores 74 Minutes
of music on a 650 MB Disc
A modern CD Player from NAD the retail price in the
UK ¤170
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