SCSI (Small Computer System Interface) Notes | I/O Interface | Working, Advantages & Diagrams

SCSI

Stands for Small Computer System Interface.
First introduced by American National
Standards Institute (ANSI) in 1986.
It has data transfer speed as 400 mbps.
It is used to transfer data between computer
and peripherals.
Types:
● Narrow SCSI - Connects 8 maximum
peripherals.
● Wide SCSI - Connects 16 maximum
peripherals.
Some computer supports more than one SCSI
in parallel connection.

Working Process of SCSI Controller:
If the Processor needs a specific data from
Secondary Storage Peripheral ( i.e from SSD or
HDD or CD-ROM ), then it sends a read request
to SCSI controller.

, Then this SCSI controller enters into the
arbitration process.
If this SCSI controller wins in the arbitration
process, it becomes Initiator (here initiator refers
to the Bus Master).
Now the SCSI act as an initiator and the Disk
Manager act as a Target.
Now SCSI sends a read request to the Target
Controller.
The Target controller accepts the request
reads the data and writes in SCSI controller.
Now the SCSI controller sends an interrupt to
the processor.
Then the Processor receives the data.



SCSI Block Diagram: