The MiniDisc (MD) was first introduced to the market by Sony in 1992 as a replacement to the audio cassette. Developed during the late 1980’s, MD used a magneto-optical system to store data recorded in real-time on a rewritable medium. The data could be randomly accessed allowing for quick seek-time and easy editing relative to the linear access of cassette mediums. The data was encoded and stored in a compressed format called Adaptive Transform Acoustic Coding (ATRAC). The ATRAC compression rate of 292kbps, called SP, allowed for 60, 74, and 80 minutes of music to be stored on a disc that could hold 20, 25, and 28 minutes of music in CDaudio quality, .WAV format.

The first MD machine was the MZ-1 recorder, which retailed for approximately 750 usd. It had line-inputs for optical, RCA audio single-line, and microphone. It’s line-outputs were for headphone and optical, but the optical line-out was an option that was discontinued from later releases of portable MD units. Sony licensed MD technology to other companies and soon Kenwood, Panasonic, Sharp, and others were releasing their own MD units, both recorders and stand-alone players. To further the integration of MD as the replacement medium for cassette, Sony offered the first home MD deck, MDS-101, and the first in-dash car unit, C670RDS, in 1994. Throughout the 90’s and into the next decade, MD ruled supreme as the medium for portable audio and recording in East Asia but never developed a mainstream following in North America and Europe.

In 2000, Sony introduced a new encoding method, MiniDisc Long Play (MDLP), that had two formats LP2 and LP4. LP2 extended the capacity of an 80 minute disc to 160 minutes by recording data at a compression rate of 132kbps and LP4 extended the capacity of an 80 minute disc to 320 minutes using 66kbps. Both SP and LP2 used separate stereo coding with discrete left and right channels while LP4 used joint stereo coding.

In 2002, Sony introduced NetMD, which allowed for the transfer of music files from computer to MD via USB connection. The software, SonicStage (SS), quickly developed a bad reputation for freezing systems, the occurrence of errors with operations successfully performed minutes earlier, restrictions on the number of times a file could be checked out, and requiring large amounts of system resources for operation. While SS, now called SonicStage CP (SSCP), has become a user-friendly and streamlined program, the memories of its first release and update are still recalled by product reviewers and DAP users when considering new Sony equipment.

The marketing by Sony also caused resentment among new users to MD via NetMD. On their websites and on the product boxes, Sony stated that NetMD could play MP3 files. What Sony failed to clarify was the MP3 file had to be imported into SS and recoded into ATRAC before it could be transferred to MD. The importing and recoding added time to complete the transfer to disc and decreased the quality of the original MP3 file.

Retailers of NetMD products also added to the negative sentiment by selling the product on merits that it did not have. Not being familiar with NetMD, many retailers erroneously informed customers that files could be transferred from the NetMD unit to the computer. Based upon this information, users would transfer files to an MD disc and erase the source file from their computer thinking it was available for reloading at a future time. The two-way transfer of files between computer and MD did not come about until the release of Hi-MD.

In 2004, Sony revamped the MD product line with the introduction of Hi-MD. This new format introduced 1GB disc memory, backwards compatibility with non Hi-MD discs, the ability to use Hi-MD as a USB connected drive, and the ability to upload ATRAC files encoded in Hi-MD file formats. For the field-recorder, the greatest improvement was the ability to record files in an uncompressed format called Linear PCM, which could easily be re-encoded into CD quality .WAV files. Unfortunately, no other companies opted to release Hi-MD portable units but Onkyo added Hi-MD to a series of home shelf stereos and mini-component systems. While Hi-MD has never found it’s way into home or car decks, companies such as Marantz, Teac, and Kenwood continue to release MDLP capable decks for such situations.

The latest release of a portable MD unit was the Hi-MD recorder, MZ-RH1, in April, 2006. This unit expanded upon the upload capabilities of the first Hi-MD units by allowing the upload of files encoded in the pre-Hi-MD file formats. This could be a sign that Sony wants to free itself of the MD legacy by allowing users to move all their data off MD and into their computer.

Regardless of Sony’s next move, the MD format has many adherents, both casual and diehards. The ability to copy music from external sources, in real-time, without being reliant on a computer keeps many radio users in the fold. With the variety of units and blank disc styles made available over the past 15 years, collectors have evolved who enjoy using their gear and displaying their collection on the internet and in person to anyone willing to look. Casual users of portable audio, field and radio recordists’, and collectors will keep MD alive even if manufacturers release no further products. MD is a format that requires a bit more personal attention than just downloading from an online music store and this creates a connection with the music and the medium which can’t be replaced by drop-and-drag digital audio players.