Compact Disc (CD) дискови носители

Compact Disc (CD) дискови носители
1978г. Philips и Sony започват производството на аудио CD-DA (12 инча)
1982г. стандарт за CD – 4.72 инча (за да се запише 70(74)min 9 симфония на Моцарт)
CD-ROM (120mm, 1.2mm, 15mm)

Производство на CD-ROM носители

A CD-ROM sector contains 2352 bytes, divided into 98 24-byte frames. The CD-ROM is, in
essence, a data disk, which cannot rely on error concealment, and therefore requires a higher
reliability of the retrieved data. In order to achieve improved error correction and detection, a
CD-ROM has a third layer of Reed-Solomon error correction.
A Mode-1 CD-ROM, which has the full three layers of error correction data, contains a net
2048 bytes of the available 2352 per sector. In a Mode-2 CD-ROM, which is mostly used for
video files, there are 2336 user-available bytes per sector. The net byte rate of a Mode-1 CDROM, based on comparison to CDDA audio standards, is 44.1k/s×4B×2048/2352 = 153.6
kB/s. The playing time is 74 minutes, or 4440 seconds, so that the net capacity of a Mode-1
CD-ROM is 682 MB.
Layout Type
CD Digital
Audio:
CD-ROM
(MODE1):
CD-ROM
(MODE2):
Legend (bytes)
12
sync
4
sector ID
data
4 error detection
8
blank/null
276 error correction

← 2,352 bytes block →
2,352 bytes of Digital Audio
12

4

12

4

2,048 bytes of user data

4

2,336 bytes of user data