IDE Training Course, Part 1: A Detailed Look at the Basics and Technology

ATA Standards At A Glance, Continued

ATA/ ATAPI-4

In 1998, ANSI included the ATAPI standard (NCITS 317, see below) in the latest version of the ATA standard, making it possible to connect CD-ROM drives and other storage media. Further changes included the introduction of the UltraDMA modes 0, 1 and 2, and the recommendation to use an 80-wire IDE cable, which could bring about significant improvements in reliability. Faster modes (ATA-4), however, make the use of higher-grade cables imperative.

To safeguard data integrity, the protocol was expanded to include CRC (Cyclical Redundancy Checking), and additional commands were defined - including what is known as Command Queuing and the possibilities of command overlapping. Due to its maximum data transfer rate, the UltraDMA mode 2 would soon be known as UltraDMA/33. Modes 0 and 1, on the other hand, were never implemented by the manufacturers.

ATA/ ATAPI-5

ATA-5 was introduced under the name of NCITS 340 in 2000. UltraDMA modes 3 and 4 were the most interesting. In order to be able to use the possible bandwidth of 44 or 66 MB/s, the use of an 80-wire IDE cable was required.

With ATA-5, some old ATA commands were thrown overboard; others were modified to face the new performance realities.

ATA/ ATAPI-6

The prevailing version of the ATA standard so far includes UltraDMA mode 5 and the expansion of the LBA mode from 28 bits (with a maximum of 137 GB per drive) to 48 bits. Furthermore, Acoustic Management is included as well. This makes it possible to use software to throttle the access speed of modern hard drives, noticeably reducing the operating noise. For the first time, ergonomics is an important factor. Efforts to officially integrate commands for the faster handling of audio and video streams are currently underway.

ATA7?
This standard does not yet exist, because Serial ATA is about to be introduced and is not supported by a number of leading manufacturers. However, if ATA7 is submitted later, it is sure to include UltraDMA mode 6.