Sunday, March 25, 2012

What is ATA?

ATA technology is a technical specification group on IDE (Integrated Device Electronics). Primarily, IDE is merely a hard disk interface technology aiming to integrate controller and disk body. As the upbeat popularization of IDE/EIDE, global standardization protocol has summarized all technical specifications since the emergence of this interface as global hard disk standard. In this way, ATA(Advanced Technology Attachment)has come into existence.

ATA technical development
ATA has experienced several modification and upgrade with each new generation based on former generation and keeping the backward compatibility. ATA-1, the first generation of ATA used on Compaq desktop 386 serial as the initial standard specification, is designed as "main/subordinate" structure serving as accessory device based on ISA96-pin and employing 40 or 44 pin connector and wire. In 44pin scheme, the extra 4-pin supplies electricity for those devices which don't has independent power interfaces. Besides, ATA-a simultaneously provides DMA and PIO to transmit signals. ATA-2 is also called as EIDE (Enhanced IDE), Fast ATA or FAST ATA-2 and DMA has been fully implemented in this edition with the standard DMA transmission speed raised from 4.16MBps of ATA-1 to 16.67MBps. 

Furthermore, ATA-2 also supports power management, PCMCIA and removable devices and a maximum 8.4GB hard disk volume via the standard addressing method CHS (Cylinder, Head and Sector). Moreover, ATA-2 has also introduced LBA which broke through the old conception of accessing disk by CHS to lay a fine foundation for accommodating the increasing hard disk volume in the future plus supporting a maximum volume of 137.4GB via increasingly upgrading BIOS or third-party software. User could find LBA or CHS setting option in CMOS as long as the computer supports EIDE. EIDE also supports more hard disks and allows two slots on motherboard with each slot connecting one main and one subordinate device so as to support 4 IDE devices.

With the introduction of self-detection and monitoring and SMART technology, IDE driver is designed and produced more reliably. ATA-3 has also added password protection measure to control access device, offering a significant safety feature. 

The most prominent two features included by ATA-4 are that ATA-4 supports Ultra DMA and integrates ATAPI standard. ATAPI provides general interfaces for CD-ROM, tape backup and other removable storage devices. Before this, ATAPI is a completely independent standard. With the entrance of ATAPI, ATA-4 put an instant effect on supporting removable medium. Meanwhile, Ultra DMA also increased the DMA transmission rate from original 16.67MB/s to 33.33MB/s. Besides, ATA-4 added 40 pin on the basis of previous 40pin to top 80pin all together among which the 40 pin are used to strengthen signal quality. ATA-4 is also called as Ultra DMA, Ultra ATA or Ultra ATA-33.

Compared with ATA-4, ATA-5 has been upgraded mainly on what kind of cable that the automatic detection device uses, 40pin or 80pin? When using 80pin cable, Ultra DMA transmission rate will be increased to 66.67MB/s. Therefore, ATA-5 is also called as Ultra ATA-66. Later, ATA-100/133 informal standards emerged with increase merely in speed. However, 100/133MBps is just a symbol due to the limitation of hard disk internal transmission speed.

A slot is included on ATA-1 motherboard supporting a primary device and a subordinate device and each device allows a maximum volume of 504MB and support 3.3MB/s transmission rate of PIO-0 mode. ATA-1 supports PIO modes of PIO-0, PIO-1,PIO-2 and four DMA modes which are not practically applied. ATA-1 interface has 5-inch hard disk rather than current mainstream 3.5 inch.

ATA-2, an expansion to ATA-1, is also called as EIDE (Enhanced IDE) or Fast ATA. ATA has been added with 2 PIO and 2DMA modes on the base of ATA, lifting the maximum transmission rate to 16.6MB/s and breaking the 504MB limit to support maximum 8.1GB hard disk by introducing LBA. In BIOS settings of computer supporting ATA-2, we can always see LBA and CHS settings. Meanwhile, there are two EIDE slots on the motherboard of EIDE interface, connecting the primary device and subordinate device respectively. Thus, a motherboard could support EIDE devices which are generally called as IDE1 and IDE2.


ATA-3 didn't introduce higher transmission speed mode and kept original speed of 16.6MB/s, but improved power management scheme by introducing simple code protection safety scheme. Meanwhile, ATA-3 still employed an epoch-making technology - the S.M.A.R.T (Self-Monitoring Analysis and Reporting Technology), which would monitor head, platter, electrical machine, circuit and other hard disk components. Via detecting monitored target with monitoring software on the host machine and detecting circuit, operating status and history information will be compared and analyzed with default safety value. When the safety value exceeds the acceptable range, warn would be sent to user so as to make effective forecast over potential hard disk error and improve data storage safety.

Since the standard ATA-4 interface began to support Ultra DMA data transfer mode, ATA-4 was also called Ultra DMA 33 or ATA33. Double Data Rate was first introduced on ATA interface, enforcing interface to perform twice data transfer, one during ascending period and another during descending period, within one clock period, which abruptly increased the data transfer rate from 16MB/s to 33MB/8. Ultra DMA 33 also introduced another new technology, CRC, which sends cyclic redundancy code and checks the code when the opposite party is receiving. Only when all checks are correct will the data be received and processed, casting strong guarantee to the safety of high-speed data transfer.

ATA-5, also called as "Ultra DMA 66" or "ATA66", is built on the base of Ultra DMA 33 hard disk interface and adopts UDMA technology. Ultra DMA 66 has the receiving/sending rate reached 66.6 MB/s, which is two times as fast as that of U-DMA/33. As working frequency increases, EMI still arises on ATA interface. To ensure data transfer accuracy and prevent electromagnetic interference, Ultra DMA 66 interface begins to use 80-cable with 40-pin. 40-pin is to be compatible with ATA slot and reduce cost and all cables newly increased on 80-cable are earth cables corresponding with original data lines which reduces electromagnetic interference between neighboring signal wires.

ATA100 interface and data line are the same with ATA66 using 40-pin 80-core data transfer cable and with complete downward compatibility. All devices supporting ATA33 and ATA66 can be used on ATA100 interface. ATA100 specification can easily deal with all current thorny problems of ATA33 and ATA66. ATA100 allow hard disk external rate to reach 100MB/s, improving hard disk data integrity and data transfer rate and considerably improving disk subsystem performance of desktop system.

ATA-7 is the last interface standard of ATA also named ATA133. Only Maxtor published a series of hard disks employing ATA133. This is the first IDE hard disk exceeding 100MB/s in terms of interface speed. Maxtor is the only manufacturer of this hard disk currently as other IDE hard disk manufacturers has stopped development of IDE interface but begun developing Serial ATA interface standard hard disk instead. ATA133 supports 133MB/s data transfer rate.

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