CD-ROM
CD-ROM arrived in Japan in 1985, when Denon and Sony introduced it at the first Japanese COMDEX computer show. Within a few years, those shiny 120 mm discs of polycarbonate plastic would reshape how software, encyclopedias, and video games reached people's homes. The format promised something genuinely new: a single disc could hold 553 megabytes of data at launch, far beyond the floppy disks that defined the era.
Before the CD-ROM existed, the idea of an optical disc that could store computer data had to be theorized from scratch. Independent researchers in the United States began that work decades earlier, and the path from theory to consumer shelf ran through laboratories in two continents and the competitive ambitions of companies like Sony, Philips, and Microsoft. How a format defined in 1983 became the dominant medium of the 1990s, and why it was largely obsolete by the early 2000s, is the story of one of computing's most consequential physical objects.
David Paul Gregg filed theoretical work on optical disc storage in 1958. James Russell continued that line of inquiry from 1965 through 1975. Gregg's patents became the foundation for the LaserDisc specification, co-developed by MCA and Philips after MCA bought both Gregg's patents and his company, Gauss Electrophysics. That LaserDisc encoded information through an analog process, which separated it from what would come next.
The shift to digital came during 1979-1980, when Toshi Doi and Kees Schouhamer Immink worked on a joint Sony-Philips taskforce. Their work produced the Compact Disc Digital Audio standard, defined in 1980. Sony and Philips then extended that format to carry any digital data, creating the CD-ROM specification in 1983 in a document that came to be called the Yellow Book. The CD-ROM was announced in 1984, introduced at COMDEX in 1985, and the first public CD-ROM drive, Philips' CM 100, shipped in July 1985.
In November 1985, Microsoft, Philips, Sony, Apple, and Digital Equipment Corporation met to define a file system for CD-ROMs. Their High Sierra format, published in May 1986, was later standardized as ISO 9660 in 1988. One of the earliest titles available on the new format was the Grolier Academic Encyclopedia, shown publicly at the Microsoft CD-ROM Conference in March 1986.
Each CD-ROM disc is 1.2 mm thick polycarbonate plastic with a thin aluminum layer that creates a reflective surface. Data is recorded as microscopic indentations called pits, separated by flat areas called lands. A near-infrared laser at 780 nm shines onto that surface; the depth of the pits runs to approximately one-quarter to one-sixth of the laser's wavelength, which causes destructive interference in the reflected beam and allows binary data to be read.
A single sector on a Mode 1 CD-ROM holds 2,048 bytes of usable data, drawn from a 2,352-byte sector structure that also carries synchronization, address, error detection, and error correction fields. A standard 74-minute disc contains 333,000 such sectors, yielding a net capacity of 650 MB. An 80-minute disc reaches 703 MB. The base transfer rate, called 1x, delivers 150 kilobytes per second, a figure derived from CD-DA audio standards and defined as the benchmark against which all faster drives are rated.
Mode 2 sacrifices the error correction bytes in exchange for 2,336 available data bytes per sector, making it better suited for video or image data where minor imperfections are tolerable. Sony and Philips extended the format further in 1991 with CD-ROM XA, first announced in September 1988, which combined compressed audio, video, and computer data for simultaneous access. Video CDs, Photo CDs, and CD-i all rely on the XA sector modes it introduced.
By 1988, CD-ROMs had entered home video game consoles. The PC Engine CD-ROM2, sold in North America as the TurboGrafx-CD, was the first console to support the format. By early 1990, roughly 300,000 CD-ROM drives had been sold in Japan, while U.S. plants were pressing approximately 125,000 CD-ROM discs each month.
1990 also saw Data East demonstrate an arcade system board that used CD-ROMs, building on the LaserDisc game tradition of the 1980s but gaining the flexibility that digital data allowed. Computers marketed through the 1990s increasingly carried the label "multimedia" specifically because they included a CD-ROM drive, which could deliver hundreds of megabytes of video, audio, and pictures that no floppy could match.
Portable computing joined the trend as well. Panasonic's CF-V21P in 1993 was the first laptop to offer an integrated CD-ROM drive, though it only accommodated mini CDs up to 3.5 inches in diameter. IBM's ThinkPad 755CD in 1994 was the first notebook to support the standard 4.7-inch disc. These machines made the format genuinely mobile just as the software industry was shifting its distribution model to take full advantage of the capacity that CD-ROM offered.
Samsung Electronics changed the conversation about maximum speeds when it introduced the SCR-3230, a 32x drive that used a ball bearing system to balance the spinning disc and reduce vibration. Before that drive, 20x had been widely considered the mechanical ceiling. By 2004, the fastest commonly available drives reached 52x, spinning at approximately 10,400 rpm with a data transfer rate of 7.62 MB/s.
At 52x, the outermost part of the disc travels at around 65 meters per second. That linear velocity creates real physical stress on polycarbonate plastic. Poorly made or physically damaged discs can shatter under centripetal stress at 10,000-13,000 rpm. Drives developed sophisticated error correction to handle the noise that high speeds introduced, and most 21st-century drives included software utilities to force lower spin speeds for quiet or accurate reading.
Kenwood's TrueX 72x drive demonstrated a different approach: seven laser beams reading simultaneously at a rotation speed of roughly 10x, achieving 72x throughput without the structural stress of extreme spin rates. A 2003 MythBusters episode mistakenly claimed that 52x speed meant 30,000 rpm, an error caused by applying that linear velocity to the disc's inner edge rather than its outer edge, where drives are actually rated. The true figure at 52x is approximately 10,000 rpm.
Several file system standards govern how data is structured on CD-ROMs. ISO 9660, the descendant of the 1986 High Sierra format, defines the baseline. ISO 13490 added support for rewritable discs and multiple sessions. ISO 13346 addressed the shortcomings of ISO 9660, and a subset of it became UDF, which DVDs later adopted. A bootable CD specification called El Torito, issued in January 1995, allowed a disc to emulate a hard disk or floppy.
Software distributors, particularly game publishers, embedded copy protection directly into the disc and the software simultaneously. A pressed CD-ROM could contain deliberately weakened sectors and additional data that was difficult to duplicate to a CD-R or disc image. The software checked for the original disc on each launch. On the hardware side, every CD writer was encouraged to encode a unique Recorder Identification Code on every disc it burned, paired with an eight-character Source Identification Code beginning with "IFPI" stamped on commercially pressed discs.
DVDs and downloadable software began displacing CD-ROMs in the early 2000s. A single-layer DVD-ROM holds 4.7 gigabytes of error-protected data, more than six standard CD-ROMs. Consumer DVD-ROM drives could deliver consistent 36x CD-ROM equivalent speeds from the outset. By the time a 700 MB disc was fully readable in under 2.5 minutes at 52x, the returns on further CD-ROM speed development had diminished to the point where the format's commercial role effectively ended.
Common questions
What is a CD-ROM and how does it store data?
A CD-ROM is a read-only optical disc that stores data as microscopic pits and lands on a reflective polycarbonate surface. A 780 nm laser reads the pattern by detecting changes in the reflected beam's intensity caused by the pit depth. A standard 120 mm CD-ROM holds 650 MB in Mode 1 format, or 703 MB on an 80-minute disc.
Who invented the CD-ROM and when was it introduced?
The CD-ROM standard was created by Sony and Philips in 1983 in a document called the Yellow Book, building on earlier work by Toshi Doi and Kees Schouhamer Immink. It was announced in 1984 and introduced at the first Japanese COMDEX show in 1985. The first public CD-ROM drive, Philips' CM 100, shipped in July 1985.
What was the first product sold on CD-ROM?
One of the first products made available to the public on CD-ROM was the Grolier Academic Encyclopedia, presented at the Microsoft CD-ROM Conference in March 1986.
What is the difference between CD-ROM Mode 1 and Mode 2?
Mode 1 uses 2,048 bytes per sector for data and adds error detection and correction bytes, making it suited for general digital data. Mode 2 allocates 2,336 bytes per sector for data by omitting error correction, making it better suited for video or image content where minor errors are tolerable.
How fast can CD-ROM drives transfer data and what is the 1x speed rating?
The 1x speed rating for CD-ROM is 150 kilobytes per second, derived from the CD audio standard. By 2004, the fastest commonly available drives reached 52x, delivering approximately 7.62 MB/s at around 10,400 rpm. The Kenwood TrueX 72x drive used seven laser beams at roughly 10x rotation to achieve 72x throughput without extreme spin speeds.
Why did CD-ROMs become obsolete in the early 2000s?
DVDs and downloading replaced CD-ROMs starting in the early 2000s. A single-layer DVD-ROM holds 4.7 GB of error-protected data, more than six standard CD-ROMs, and consumer DVD drives delivered 36x CD-ROM equivalent speeds from the start. Commercial use of CD-ROMs for software distribution is now rare.