What is SCSI?

SCSI stands for Small Computer System Interface.

It was originally derived from SASI (Shugart Associates System Interface) as an attempt to come up with an intelligent, non-device specific bus to connect peripherals to a PC. Currently, SCSI allows for up to fifteen devices in series (plus controller) and each is assigned a unique SCSI ID from 0 to 15. Each of those devices can in turn address up to 64 logical units (LUN - or Logical Unit Number), although a hard drive will typically have only one LUN. SCSI is considered a `negative bus' which means all signals are negated by being pulled or driven high and are asserted by being driven low. Due to the large number of devices SCSI is capable of addressing, the bus must be terminated.

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