DAT or DSS?

What Do You Call This, DAT or DDS?

Adapted from the DDS Manufacturers Group Newsletter - No 9 - December 1993 (Bert Vermeulen - Hewlett-Packard)

From the early days of introducing data storage applications for Digital Audio Tape technology, there has been confusion about what to call this stuff. In this paper I would like to shed some light on this issue and hopefully provide conventions that will facilitate consistency among industry participants.

What is DAT?

DAT stands for Digital Audio Tape. This acronym was originally established to talk about a consumer audio recording technology based on 3.81 mm (0.15 inch) wide tape used in a helical scan recorder compatible with the DAT Conference Standard, a book available from EIAJ (the Electronic Industries Association of Japan). The term DAT should be used in the following cases:

• When referring to the general technology. For example: "DAT recording technology has more tracks per inch than 8mm recording technology".

• When referring to the consumer or professional audio technology (recorders, players or media). For example: "DAT recorders cost about the same as Minidisk or DCC recorders, but have better sound reproduction". Another example is: "This DAT tape will hold about 120 minutes of music".

What is DDS?

DDS stands for Digital Data Storage. DDS is a data storage format which was developed by Hewlett-Packard and Sony so that DAT drives could be used for reliably storing computer data. DDS has a logo associated with it which is protected as a trademark. This trademark logo is primarily used to distinguish media that meets the environmental and durability requirements of data storage applications, and is suitable for use in a drive which records data in the DDS format. DDS media must meet a specification that is set out in ISO/IEC 10777 (for 60m DAT) or ISO/IEC 12247 (for 90m DDS). To use the DDS logo, media must be approved through a process managed by Sony. The DDS logo can also be used on drives from manufacturers licensed by HP and Sony that meet the specifications set out in the ISO/IEC standards identified above. DDS-DC is a companion format with several extensions that allow data compression to be used on DDS. There is no separate logo for DDS-DC, and DDS-DC drives use normal DDS media. There are new logos for DDS-2, DDS-3 and DDS-4, which are higher capacity formats based on DDS. DDS-2, DDS-3 and DDS-4 media are different from DDS media and will only work in drives which support these new formats.

The term DDS can be used in the following cases:

• When talking about the format: "All drives using the DDS format can interchange data with each other". Note that the word format can be omitted: "All DDS drives can interchange data with each other".

• When talking about the media for data applications : "If you don't use DDS media to store your data, you don't know whether you'll ever see it again", or "A 90-meter DDS cartridge will store 2GB and a 60-meter DDS cartridge will store 1.3GB".

• Note that it is possible to call something a DDS drive when talking about its format. Manufacturers are encouraged to refer to their data storage products as DDS.

The term DDS-DC can be used in the following case:

• When referring to a DDS drive that uses the data compression extensions. Note, all of the DDS-DC drives available today use the DCLZ data compression method and can therefore exchange compressed data.

Finally, the terms DDS-2, DDS-3 and DDS-4 can be used in the same way as DDS. Generally speaking a DDS-2 drive can also read and write the original DDS format on the original DDS tapes, so it is still appropriate to call this a DDS drive (or DAT drive).

Other Forms of Address

During the course of the last several years, we have come up with one other name: Media Recognition System. Media Recognition System (which is protected as a trademark, but should not be abbreviated because MRS is a trademark owned by someone else) is an optional system for allowing a DDS drive to distinguish DAT media from DDS media. An example of usage would be: "This DDS drive has incorporated the Media Recognition System". In relation to DDS drives and DDS media, the Media Recognition System has its own logo associated with it. This is a DDS logo with four bars after it representing the recognition stripes that distinguish a Media Recognition System tape from a tape without these features. For use of this logo, media must be approved through a process managed by Sony.

The term Media Recognition System can be used on DDS drives licensed by HP and Sony. It is not appropriate to use the four bar logo in relation to the DDS-2 and subsequent formats.

Some other terms that have been used for these technologies are:

• 4mm. This is as a way of contrasting this technology with 8mm recording technology that is used for video and data storage applications. It isn't correct to call this technology 4mm, but one should recognise that audio compact cassettes also use 4mm, so one would technically need to say 4mm helical scan. It is also worth noting that 8mm tape is exactly 8mm wide, while our "4mm" media is actually 3.81mm, wide.

• Data/DAT is a format that is very different from DDS and therefore DDS drives are definitely not Data/DAT drives.

• Helical Data Storage is a term that has been used by some people to refer to DDS, Data/DAT and 8mm collectively. It has largely fallen out of use.