IDE interface:
IDE (Integrated-Drive-Electronics) interface is a widely used external interface primarily used to connect hard disk and CD-driver which employs 16 bit data parallel transmission mode with features of small size and rapid data transmission speed. One IDE interface can connect only two external devices.

IDE, short for “Integrated Drive Electronics”, originally refers to hard disk driver that integrates hard disk controller and drive, cutting down hard disk electric cable number and length, enhancing data transmission reliability, easing the production of hard disk as the manufacturer no longer needs to concern the compatibility with controllers produced by other manufacturer. For user, the installation of hard disk becomes more convenient and easier. IDE interface technology has been developing and improving performance since its emergence and made it irreplaceable by other hard disks thanks to the low cost and high compatibility.

Evolution
IDE interface in the early stage has two transmission modes: PIO (Programming I/O) and DMA (Direct Memory Access). Though occupying litter system resources, DMA requires extra driver or set, resulting in low acceptance. As the increasing demand for speed later on, operating system begins to support DMA directly owing to the excellent execution efficiency and manufacturers have issued faster and faster DMA transmission speed standards. From 430TX chip set of Intel, it provided support to Ultra DMA 33, offering the maximum data transmission rate of 33MB/sec. And soon the later ATA 66, ATA 100 and ATA 133 proposed by Matrox were provided with 66MB/sec, 100MB/sec and 133MB/sec maximum data transmission rate respectively. It is noteworthy that the ATA 133 standard is not extensively supported in the industry. Among hard disk manufacturers, only Matrox employs ATA 133 standard while IBM, WD and Seagate adopts ATA 100 standard. And among chip set manufacturers only VIA, SIS, Ali and nVidia supports ATA133 standard with Intel only supporting ATA 100.

Notice
All IDE standards are excellently compatible with downward standards, for example ATA 133 is compatible with ATA66/100 and Ultra DMA33, ATA 100 is compatible with Ultra DMA 33/66.
Special attention should be paid that special 80-core IDE ribbon cable must be used for ATA 66 and its above IDE interface transmission standards, which was increased by 40 ground wires to improve signal stability in comparison to ordinary 40-core IDE ribbon cable.
IDE stands for one type of hard disk. However, in practical applications, people are accustomed to calling the earliest IDE ATA-1 which has been eliminated and was derived into ATA, Ultra ATA, DMA and Ultra DMA. Currently, hard ware interface has transferred to SATA and IDE interface will soon or later quite the stage.

Advantages and disadvantages of IDE:
Advantages: low cost, high compatibility, high cost performance
Disadvantages: slow in data transmission, short cable length, few connecting device