ATA (Advanced Technology Attachment) refers to a common standard used to connect hard drives and other storage devices to a motherboard. It is also referred to as IDE (Integrated Drive Electronics), though the terms are not technically interchangeable. Ultra ATA is simply next generation ATA with improved transfer speed and architecture. There are several buzzwords surrounding this technology that can make it a little confusing for consumers, but each buzzword refers to an aspect of the standard.
UDMA (Ultra Direct Memory Access): To begin, Ultra ATA is based on a joint venture design between Intel, Quantum and Seagate. It is written around a specification that allows a hard disk or drive to transfer data directly to the computer's system memory without having to use the CPU to direct this action. This saves processor resources and increases performance, which is why it's also called Ultra DMA (or UDMA) for short.
ATAPI (Advanced Technology Attachment Packet Interface): Originally, ATA was designed exclusively for hard drives, but later ATAPI integration opened the specification to include CD-ROM drives, DVD players, tape drives and other storage devices. The specification then became known as ATA/ATAPI.
PATA (Parallel ATA): ATA devices use parallel cables. Most people are familiar with these wide, flat IDE cables that connect the drives to the motherboard. Standard ATA uses 40-pin cables, while most Ultra ATA drives use 80-pin cables. Before the development of serial ATA (SATA), this term wasn't used.
There are also escalating grades of the technology that are defined by transfer speed ceilings, including Ultra ATA/33, Ultra ATA/66 Ultra ATA/100 and Ultra ATA/133. This last is the fastest, with a transfer rate of 133 megabytes per second, roughly comparable to the earliest version of SATA. While SATA drives have long out-paced Ultra ATA drives for performance, the latter is still an excellent economical choice. Aside from their use as system drives, these drives are also popular backup and archive drives.
People who are purchasing a hard drive that uses this standard or an ATAPI device will need a UDMA controller to take over the responsibility of directing data flow between the system memory and the component device. This controller is built into the motherboard chipset in most cases. For motherboards that are not compliant, a UDMA controller card can be purchased and added to an open PCI slot on the motherboard.