CD-ROM

CD-ROM (an acronym for Compact Disc Read-Only Memory) is an optical media format that was popular in the 1990s. It was superseded by DVD-ROM drives and the Apple SuperDrive in Macs.

History
Early Apple CD-ROM mechanisms used SCSI connectors, typically set to ID #3. The original Red Book standard for compact discs specified a bit rate of 153,600 bytes (150 KB) per second, referred to as "1x" CD-ROM speed.

External models

 * AppleCD SC (1x speed, model M2850) — required a CD caddy. Introduced in 1988, the internal fan was found to be drawing dust into the CD mechanism which had no external door; it was deemed unnecessary and left out of units manufactured from early 1990.
 * AppleCD SC Plus (1x speed, model M3021) — required a CD caddy. Introduced in 1991, the new drive mechanism added a drive door to keep out dust and could read CDs with more data than 650 MB (the original Red Book standard) up to 750 MB.
 * AppleCD 150 (1x speed, model M3022) — smaller enclosure, still required a CD caddy.
 * AppleCD 300 (2x speed, model M3023) — same enclosure as AppleCD 150, still required a CD caddy. Introduced in 1992.
 * AppleCD 300 Plus (2x speed) — same enclosure as AppleCD 150, but introduced a built-in CD tray and no caddy needed.
 * AppleCD 300e Plus (2x speed, M2918) — included a CD tray, revised enclosure.
 * AppleCD 600e (4x speed, model M3958) — included a CD tray, same enclosure as AppleCD 300e Plus.
 * Apple PowerCD (4x speed) — based on Philips CDF-100. Included Photo CD support with built-in audio/video out.

Internal models

 * Apple CR-503-C (2x speed CD-ROM), used in AppleCD 300 Plus.
 * Apple CR-504-C/K (4x speed CD-ROM, a.k.a. AppleCD 600i)
 * Apple CR-504-L (4x speed CD-ROM), also used in Bandai's Pippin consoles.
 * Apple CR-506-C (8x speed CD-ROM, a.k.a. AppleCD 1200i)
 * Apple CR-507-C (12x speed CD-ROM, a.k.a. AppleCD 1800i)
 * Apple CR-508-C (24x speed CD-ROM)

Driver software
Classic Mac OS included an Apple CD-ROM extension, which at first only supported Apple-branded hardware. This forced users of drives from other manufactures to resort to using a range of 3rd-party drivers with varying degrees of compatibility. Apple started making its CD-ROM extension "universal" with version 5.3.1, which was included with Mac OS 7.6.

The Apple CD-ROM extension was superseded by the Apple CD/DVD Driver included with Mac OS 8.1, which again limited compatibility to drives supplied by Apple. However, this could be hacked to support 3rd-party drives.