The first was DAT (Digital Audio Tape) which uses a Helical Scan technique (with a rotating drum similar to the one in VCR's) to record the audio. See the DAT-heads FAQ for more info.

Contrary to the time when the CD was conceived by Sony and Philips (actually CD was developed in Eindhoven in the Philips audio labs), the parties didn't come to an agreement: Philips' opinion was that the new standard would benefit consumers if it would be compatible with traditional analog compact cassettes while Sony's opinion was that optical disc technology is the future.

Anyway, Philips and Sony went their separate ways this time and Sony developed MiniDisc (see the Sony MD homepage and the MD mailing list homepage) and Philips and Matsushita (Technics/Panasonic) developed a new standard which was first known in the streets as S-DAT (Static-heads Digital Audio Tape) and later became DCC.

In order to reduce the amount of data needed to fill a DCC-tape or MiniDisc, some kind of compression scheme would be needed. This proved to be a difficult task so the introduction was postponed several times. Both MD and DCC were eventually released almost simultaneously around the end of 1992. The sound quality of the MD was significantly worse than DCC because Philips had used a 4:1 compression scheme similar to MPEG-audio level 1 (see PASC) with which they had a lot of experience, while Sony used a whole new scheme that compressed 5:1 but initially produced audible differences with the original even after only one recording generation.

Since then, Sony cleaned up their act and improved their compression chips, which now perform much better. Especially in Japan, MiniDisc caught on really well. In Europe (and especially in the Netherlands), DCC did much better. On October 31st, 1996, Philips announced that it is stopping production of DCC for home use (there was also a followup-article in the same newspaper). Philips had already admitted that DCC didn't sell as well as they had expected and had turned out to be a "niche market product for audiophiles". They also acknowledged (again in the same newspaper) that Philips will produce a MiniDisc recorder for the Japanese market, and Marantz now have some MD equipment available.

In the mean time, Sony are now aggressively marketing MD as "The new standard for digital recording".

In October 1997, Philips introduced the CDR-870, a CD-RW (CD-rewritable) recorder for home audio use which can record digital audio on a rewritable CD or on a non-rewritable CD-R (only special - more expensive - audio discs will work, normal "professional" CD-R's won't). Of course it's SCMS protected, but the DCC-L list members seem to agree that this may be a serious competitor for MD. It also seems Philips has decided to market it a bit more aggressively than DCC but it may be too early to tell.

• All DCC players and recorders can playback traditional analog cassettes.
• All DCC players and recorders are auto-reverse.
• All DCC players have music searching capabilities. As far as I know this goes for ACC as well on most recorders and players (it works by searching silences there). On prerecorded cassettes you can search by title and the player will know which side it is on.
• DCC equipment is cheaper than DAT or MD. This is now especially true because the format was discontinued, but it was also the case when DCC was still "on".
• Prerecorded DCC's seem to be more common than prerecorded MD's, at least they are over here because the largest chain of record shops ("Free Record Shop") declined to sell prerecorded MD's. Pre-recorded DAT's don't exist as far as I know.
• There's a portable DCC recorder that can be attached to a PC via the parallel port (DCC175 and DCC-link). You can save audio tracks to harddisk, edit them and play them back later, and there's also a backup program included. No such thing exists for DAT or MD (Digital sound cards exist and I heard that a SCSI MD player is available but it doesn't do audio).
• All DCC players and recorders have digital outputs (except car stereos), all DCC recorders have digital inputs. Again: as far as I know.

• Recording analog cassettes is not possible (probably the reason why many people didn't buy a DCC recorder - it didn't really replace the cassette deck)
• Although the system is theoretically capable of handling a tape drop-out of up to 3 seconds, this redundancy is not used to continue the audio playback during the changeover from side A to side B which may take a second. Also, the changeover takes longer on a stationary deck than on a portable because portables have fixed double-sided heads whereas decks have heads that are physically turned around 180 degrees for the B-side.
• It may take some time for a player to search a fragment of audio on the tape; especially portables are notoriously slow. However the latest generation of Philips decks have a "turbo drive" which rewinds a 90-minute tape in about a minute.
• Not all DCC recorders can record user text (tape title, song titles and artist names) to tape. Others can't display them. This data is recorded at the start of each track only (whereas prerecorded tapes have this information on the tape in a continuous stream) so the recorders that can display this data will only show it after they crossed a start-of-track marker in playback mode.
• DCC recorders (like all other home-use digital audio equipment) are equipped with SCMS so you cannot digitally copy from a source that already is a copy.
• The DCC175 and DCC-link are available only in The Netherlands and only for Windows on the PC. Also, you need to connect the recorder to the computer to playback files from the harddisk (there are ways around that problem though).
• DCC was discontinued at the end of October, 1996.

• DCC recorders for home use are not produced anymore. Apparently Philips stopped production as soon as the announcement was out. So, recorders that are "in the pipeline" may be available for some time but not much.
• Philips explicitly stated that they will still make DCC recorders for professional use (they could have been referring to the Marantz portable, which seems to be a DCC-170 with some extras. See also the section about recorders).
• Philips committed itself to at least 10 years of support. That means that tapes, service and service documentation will be available from them for the next 10 years. They also did this for the VCC / Video2000 VCR system.
• For a short time, DCC-175 owners who phoned the consumer line in the Netherlands to inquire about the PC-link cable were put on a list, to see if another batch of the cables would be made. Eventually, not enough people applied and now there's a big shortage of cables.