The SCSI (Small Computer System Interface) bus is a high-speed parallel interface that allows for the connection of various peripheral devices to the computer's processor. The SCSI bus is responsible for facilitating communication between the processor and the attached devices, such as hard drives, tape drives, scanners, and printers.

The SCSI bus is connected to the processor through a SCSI controller, also known as a host adapter or SCSI host bus adapter (HBA). The SCSI controller acts as an intermediary between the processor and the SCSI bus, managing the flow of data between the two.

The SCSI controller is typically integrated into the motherboard of the computer or added as a separate expansion card. It is responsible for controlling the transfer of data between the processor and the SCSI devices connected to the bus.

The SCSI controller communicates with the processor through the computer's main system bus, such as the PCI or PCIe bus. It receives commands from the processor, such as read or write requests, and translates them into the appropriate SCSI commands that can be understood by the attached devices.

The SCSI controller also handles the configuration and management of the SCSI bus. It detects and identifies the connected devices, assigns them unique SCSI IDs, and determines the order of priority for data transfer. It also provides the necessary electrical signals and protocols to ensure reliable communication between the processor and the devices.

In summary, the SCSI bus is connected to the processor through a SCSI controller, which acts as an interface between the two. The SCSI controller manages the flow of data between the processor and the SCSI devices connected to the bus, as well as handles the configuration and management of the SCSI bus.