Disk controller

It also provides an interface between the disk drive and the bus connecting it to the rest of the system.

[1][2] Early disk controllers were identified by their storage methods and data encoding.

Run length limited (RLL) controllers used data compression to increase storage capacity by about 50%.

The most common types of interfaces provided nowadays by host controllers are PATA (IDE) and Serial ATA for home use.

Signals read by a disk read-and-write head are converted by a disk controller, then transmitted over the peripheral bus, then converted again by the host adapter into the suitable format for the motherboard's bus, and then read by the CPU into the memory (RAM).