CD-ROM | Code Like It's 198x

In April 1991 ACE explained CD-ROM to its readers and reached an odd verdict. The disc was “pretty useless for most games applications”, because it was slow to send data and slow to find it. The magazine still predicted that CD-ROM would win the “games data-storage wars”, because it could hold 550 megabytes, was “difficult to pirate”, played CD-quality sound and was “in pence-per-K, an extremely cheap storage medium”. Both halves of that verdict held for the next decade. CD-ROM gave games recorded music, speech and video, and made them wait for all three.

Fast facts

Standard: the Yellow Book, Philips and Sony’s specification for data on a compact disc. Philips put its first drive on sale in 1985.
Sector: 2,048 bytes of data in Mode 1, read at 75 sectors a second.
Capacity: follows the disc’s running time. A 60-minute disc holds about 540 MB; the later 74-minute disc about 650 MB.
Speed: 150K a second at single speed, 300K at double speed.
Access time: about half a second on average; Commodore quoted 0.5 seconds for the CDTV.
First on a games console: NEC’s CD-ROM² for the PC Engine, December 1988.

Capacity is measured in minutes

A CD-ROM is an audio CD carrying data, so its size is set by playing time before it is counted in bytes. The disc spins past the laser at 75 sectors a second, and in the usual mode each sector holds 2,048 bytes of data. A 60-minute disc therefore has 270,000 sectors, about 540 MB. That is the figure Commodore gave for the CDTV in 1991, “about 700 Amiga floppy disks”, and the one Sega’s disc format specification for the Mega-CD uses. The familiar 650 MB belongs to the later 74-minute disc. Some of the space was never the game’s: on the Mega-CD the first sixteen sectors were reserved for the system.

Nothing else a games machine could read came close. The same disc could carry an hour of CD-quality music, or be divided between music, speech, pictures and program.

Slow to find, slow to read

Speed was the catch. The CDTV’s drive delivered 153,000 bytes a second, and Sega’s Saturn manual defines “normal speed” as the same 150K. ACE compared that with the fastest hard disks of 1991, at around a megabyte a second.

Finding the data was worse. A CD stores its data on one long spiral, and the drive must move the laser and change the disc’s speed before it can read. Commodore quoted an average access time of half a second for the CDTV and 0.8 seconds at worst. Edge’s 1993 feature on CD put it bluntly: “CD data access is slow. Very slow. What’s the use of 650 meg of space when you can’t quickly break in and access parts of it?” It reckoned a hard drive found data 500 times faster. The Multimedia PC standard, launched in October 1991, asked only that a drive sustain 150K a second with an average seek time “of one second or less”, as Compute! reported in December 1992.

Double speed halved the wait but did not end it. Sega’s Saturn manual allows an average of up to 500 ms at double speed. Reviewing the first 3DO games in 1994, Edge found that “the main trouble” was the disc accessing: the double-speed drive was a sluggard “compared to even the most basic cartridge”.

Cheap to make

The saving was in the factory. In November 1993 Edge reported that a CD cost “around 50p” to press, where a cartridge cost a publisher £5 to £12. By 1996 it put a PlayStation or Saturn disc at under $10 including Sony’s or Sega’s licence fee, against an estimated $30 or more for a Nintendo 64 cartridge.

The machines

PC Engine CD-ROM² (NEC, December 1988). The first CD-ROM drive for a games console, sold in Japan as an add-on that locked onto the console. It brought recorded soundtracks and spoken scenes to games.
FM Towns (Fujitsu, 1989). A Japanese 32-bit computer with a CD-ROM drive as standard. The Games Machine called it “the big sensation in Japan” in February 1990.
CDTV (Commodore, 1991). Commodore’s “combination of Amiga and CD player”, launched to the press on 30 April 1991 and priced at £599 in Britain, with a single-speed drive.
CD-i (Philips, 1991). Philips’s own interactive CD player. It had been on sale in the US “for over a year” when it reached Britain at £599 in 1992.
Mega-CD (Sega, December 1991). A CD drive for the Mega Drive, launched in Japan on 12 December 1991 with its own 68000 at 12.5 MHz. Sega announced the US version, the Sega CD, at $299.95 for November 1992.
CD32 (Commodore, 1993). Commodore’s Amiga-based console, launched at the Science Museum in London on 16 July 1993 at £299.99. Its double-speed drive read “up to 300k per second”.
3DO (1993) and the PlayStation (December 1994) and Saturn (November 1994) made CD the main format of a console generation, all with double-speed drives.

On the PC, drive prices fell from $800–$1,000 in 1990 to “as little as $400” by mid-1991, according to Compute!, and games such as The 7th Guest and Myst (both 1993) were built for the disc from the start. By January 1994 Computer Gaming World was grumbling that, as soon as buyers had single-speed drives, publishers were talking about whether to “require double-speed and recommend triple-speed CD-ROM drives”.

What the space was used for

Most of the extra room went on sound and pictures rather than bigger game worlds. CD audio tracks played straight from the disc gave consoles recorded music. Speech replaced text. Full-motion video filled the rest, sometimes as the whole game. The slow drive shaped that video. A single 320 × 200 picture with one byte per pixel is 64,000 bytes, so a drive delivering 150K a second could feed fewer than three uncompressed frames a second. Video on CD had to be compressed, shrunk or both.

Sources

ACE issue 43, April 1991: “What is a CD-ROM?”, the 150K transfer rate, access time, “pretty useless for most games applications” and the advantages that followed. Issue 30, March 1990: glossary, the Yellow Book as “the Philips/Sony book of standards for CD-ROM technology”.
Commodore, CDTV Service Manual (1991): the drive specification, transfer rates, access times and capacity.
Sega, Mega-CD Disc Format Specifications (undated; unpublished Sega document): sector count and capacity for a 60-minute disc, and the reserved system area.
Sega, Sega Saturn Hardware Manual: Overview Manual (1997), table 3.10: normal and double-speed read rates and access times.
Edge issue 2, November 1993: CD-ROM feature on access times, hard drive comparison, disc and cartridge costs. Issue 5, February 1994: 3DO disc access. Issue 13, October 1994: the PlayStation’s double-speed drive. Issue 29, February 1996: PlayStation and Saturn disc costs against Nintendo 64 cartridges.
Compute! issue 147, December 1992: the Multimedia PC drive requirements. July 1991: CD-ROM drive prices.
Computer Gaming World issue 114, January 1994: publishers and double-speed drives. issue 90, January 1992: the Multimedia PC launch on 8 October 1991.
The Games Machine issue 27, February 1990, pp. 20–21: the FM Towns.
Amiga Format issue 23, June 1991: the CDTV press launch on 30 April and the £599 price. Issue 38, September 1992: CD-i’s UK launch at £599. Issue 51, October 1993: the CD32 launch at the Science Museum on 16 July and its £299.99 price.
CU Amiga, December 1993: the CD32’s double-speed drive.
Game Informer issue 4, March 1992: the Mega-CD’s Japanese debut on 12 December 1991 and its 12.5 MHz 68000.
Sega Visions, August 1992: the Sega CD’s $299.95 price and November availability.
Wikipedia, “CD-ROM” (web, secondary): the Yellow Book’s creation in 1983 and Philips’s CM 100 drive of July 1985. https://en.wikipedia.org/wiki/CD-ROM
Wikipedia, “FM Towns” (web, secondary): the FM Towns’ release in February 1989. https://en.wikipedia.org/wiki/FM_Towns