Moving the HDD controller from the interface card to the disk drive helped to standardize the host/controller interface, reduce the programming complexity in the host device driver, and reduced system cost and complexity.Overview are accessed over one of a number of types, including (PATA, also called IDE or ; described before the introduction of SATA as ATA), (SATA),, (SAS),. The earliest hard disk drive (HDD) interfaces were bit serial data interfaces that connected an HDD to a controller with two cables, one for control and one for data. An additional cable was used for power, initi. Historical Word serial interfaces connect a hard disk drive to a bus adapter with one cable for combined data/control. (As for all early interfaces above, each drive also has an additional power cable, usually direct to the power s.
[pdf] Sometimes the optical module is replaced by an electrical interface module that implements either an active or passive electrical connection to the outside world. This is used when the link is short, particularly when connecting to a top of rack switch. OverviewAn optical module is a typically hot-pluggable optical transceiver used in high-bandwidth data communications. There have been multiple variants of the electrical interface of optical modules that have been used over the years. The earliest forms of optical modules had an analog electrical interface. In the transmit dir. Many different forms of optical modulation and multiplexing have been employed in optical modules. The most common modulation technique historically has been or NRZ.
[pdf] 
