SONY’S MINI DISC
The end of tape?

Sony has recently announced yet another digital media format. The 2.5-inch “Mini Disc” (MD) could presage the beginning of the end for audio tape and could introduce a compact CD-audio data format with immense appeal for multimedia and computer applications.

The Mini Disc is made possible by two very impressive technologies. The first is a specially designed laser read/write system that enables an MD player to write (and read) a magnetic-optical disc as well as to play read-only optical CDs. This means that the same inexpensive drive can be used to record (and play back) digitally encoded music as well as to play back mass-produced optical CDs.

The second technology is a digital sampling technique that allows the Mini Disc to record 74 minutes of near-CD-quality stereo sound on a disc that holds just over one-fifth the data of a conventional CD.

The disc itself will be housed in a plastic “caddy” similar to that used for the familiar 3.5-inch computer disks. Data is read off the disc at the same rate as from a standard CD (approximately 1.4M bits/second), but it is fed to the decoder at 300K bits/second. An inexpensive 1M-bit memory chip can provide up to three seconds of buffering and make the disc drive virtually immune to shock and vibration.

Markets. Sony is clearly targeting the audio market now served by tape cassettes, especially “Walkman” type portables, boom boxes and car stereos. The Mini Disc should be able to serve all of these markets better than even digital tape. (Imagine a 15-disc MD changer in your car’s dashboard!)

Although MD players will not be available until the end of 1992, it looks like a winner.

The Sony digital audio tape (DAT), Philips/Tandy Digital Compact Cassette (DCC) and Sony Mini Disc technologies will be examined in our next issue.

- Jonathan Seybold