Saturday, June 20, 2009

IDE/ATA

IDE (Integrated Disk Electronics) refers to disk with a logic board built-in, as comparing to older disk. ATA (AT Attachement) refer to the interface of IDE disk. ATA disks requries a controller which is built into the motherboard. ATA cables has a maximum length of 18 inches and uses 40-pins. The cable contains an extra 40-wires which do not connect to the pin to improve insulation.

Early ATA disks were addressed by CHS (Cylinder/Head/Sector). The disparaty between the ATA standard and older BIOS on the number of bits used for CHS has limited the size of IDE disk to 504MB. Newer BIOS translate the CHS address to ATA standard and this extended the addressability to 8.1GB. To overcome the limitation, CHS was replaced by LBA (Logical Block Address) in later ATA standard.

ATA-1 (1994) - support CHS and 28-bit LBA
ATA-3 (1997) - added Self-Monitoring Analysis amd Reporting Technology (SMART) which allows monitoring of several parts of the disks. Another feature was Password Protection.
ATA/ATAPI-4 - ATA Packet Interface for removable media. ATAPI used the same cable and controller but required special drivers. 80-wire cable was introduced. Add HPA (Host Protection Area) for vendor to keep data that would not be erased by formatting the disk.
ATA/ATAPI-6 (2002) - Added 48-bit LBA and removed support for CHS. Add DCO (Disk Configuration Overlay).
ATA/ATAPI-7 - Included serial ATA

No comments: