Small Computer Systems Interface

Akronim: SCSI

SCSI
Small Computer Systems Interface. cf IDE. SCSI
can be used to interface to any device that has a SCSI interface, this includes
devices such as printers and scanners as well as the more traditional disk and
tape drives.
SCSI adapters typically support one or two SCSI buses, each of which can
support up to eight units. Each device on the SCSI bus is identified by a SCSI
ID, which ranges from 0 to 7 (or sometimes 0 to 15). The SCSI adapter itself
will occupy one of these SCSI IDs leaving 6 (or 14) available for other devices.
There are a number of different types of SCSI, reflecting its continuing
development, and these are summarised in the following table:


SCSI Type
Data Width
Transfer Rate
Max devices
Max cable length (metres)


SCSI-1
8 bits
5MB/sec
7
6 m (SE) or 12 m (LVD)


SCSI-2
Fast (Narrow)
8 bits
10MB/sec
7
3 m (SE) or 12 m (LVD)


Fast Wide
16 bits
20MB/sec
15
3 m (SE) or 12 m (LVD)


SCSI-3
Ultra (narrow)
8 bits
20MB/sec
7
1.5 m (SE) or 12 m (LVD)


Ultra Wide
16 bits
40MB/sec
7 (SE) or 15 (LVD)
1.5m (SE) or 12m (LVD)


SCSI-4
Ultra 2 (narrow)
8 bits
40MB/sec
7
12m (LVD)


Ultra 2 Wide
16 bits
80MB/sec
15
12m (LVD)


Ultra 3 (narrow)
8 bits
80MB/sec
15
12m (LVD)


Ultra 3 (wide)
16 bits
160MB/sec
15
12m (LVD)


Ultra 320 (wide)
16 bits
320MB/sec
16
12m (LVD)


Note:

The transfer rate is the maximum throughput of data on the bus, it does
not indicate the maximum throughput of a device connected to the bus (for
example the bus might be capable of 80MB/sec but a disk drive connected
to it might be cable of only a fraction of that.)
The maximum cable length (which is the length from the adapter to the
last device or terminator) may reduce as devices are added.

Relevant links:

www.ramelectronics.net/html/scsi_connecters.html
- Pictures of various different types of SCSI connectors.


www.hardwarecentral.com/hardwarecentral/tutorials/36/1/ - Introduction
to SCSI

Inne definicje z Informatyki na literę S.