1. Small Computer System Interface (SCSI) is pronounced as "scuzzy".
2. It is a "system" level interface for multiple storage devices.
3. It is considered a "bus" that supports up to 7 devices plus a "host" adapter card.
4. Each SCSI host adapter card fits in an expansion slot on the motherboard. Each can handle up to 7 devices.
5. A SCSI hard drive usually comes with the drive, controller, and SCSI adapter in one circuit.
6. SCSI is a hardware standard - 1986.
7. Usually, the SCSI adapter requires a "driver" or software to tie it to your PC.
8. SCSI (1986), SCSI-2 (1994), and SCSI-3(still being defined- 1996).

Each SCSI controller can support up to 7 devices plus the controller card for each SCSI controller installed. A SCSI controller is installed in an expansion slot on the motherboard.

Standard SCSI has 8 and 16 bit data bus interface. The 8-bit interface can transfer data at 5 MB/s, and the 16 bit bus can transfer at 10 MB/s.

The SCSI-2 (known as FAST SCSI) at 10MB/s over an 8 bit bus, or 20MB/s over a 16 bit bus.

The SCSI-3 (known as "Ultra-SCSI" is already being sold, and can transfer data at 20MB/s over 8 bit buses, and at 40MB/s over 16 bit buses.

ADVANTAGES OF SCSI Devices:

1. More devices can be attached to a single cable (7) than can be attached with IDE controllers (2).
2. Each SCSI drive has it's own embedded disk controller that can function independently of the system CPU.

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Storage Devices