The standard describes the mechanical, electrical and functional bus specifications.


There is the standard SCSI-1, SCSI-2 and SCSI-3.

This bus differs from others in that it deported the complexity to the device itself. Thus, orders sent to the device can be complex, the device should then (eventually) break them down into simpler tasks, which is advantageous if we work with multitasking operating systems.

This interface is faster, more universal and more complex interface E-IDE including the main disadvantage is to capture a sizable percentage of the processor, which is a handicap when many flows of data are simultaneously open.

Smarter and less dependent on the central unit, the SCSI interface can manage internal and external devices varied, such as hard drives, scanners

3D scanner

A three-dimensional scanner is a device that analyzes the objects or their immediate environment to gather specific information on the form and possibly on the appearance (color, texture) of these. The data collected can then be used to build CGI three-dimensional (digital objects) for various purposes.
These devices are much used by the industries of entertainment for movies or video games. Digital images of ......

, recorders, backup units, etc.

The SCSI-2 standard specifies that the bus can connect computers with devices such as :

-hard drives
-floppy drives
-magnetic tape drives
-printer

3D printer

3D printing is an additive production technique developed for rapid prototyping. Its goal is to quickly and easily generate a physical piece. Different materials can be used, more generally ABS plastic, PLA plastic, and metal, but also wax, or even plaster.
The applications of 3D printing are varied, but in all cases aim to concrete visualization of projects, or verification of parts ergonomics. 3D printing ......

s
-(WORM) optical disk drives
-optical disk drives (CD

The CD player

It's a drive optical drive that reads through a laser diode optical discs called CDs or CD, be it CD or computer CD-ROM. When it is used to listen to music CDs, the CD player can be integrated into various types of portable devices or servants, to a radio handset, etc. It can also be a separate, portable device or domestic, to connect to a channel Hi-Fi, an audio amplifier or headphones.
Computer, the CD playe......

-ROM)
-scanners

3D scanner

A three-dimensional scanner is a device that analyzes the objects or their immediate environment to gather specific information on the form and possibly on the appearance (color, texture) of these. The data collected can then be used to build CGI three-dimensional (digital objects) for various purposes.
These devices are much used by the industries of entertainment for movies or video games. Digital images of ......

-medium changer
-communication devices

The standard does not restrict the use of the bus for the interconnection of a computer with devices, but it can be used between computers, or to share peripherals between computers.

The SCSI-3 standard is more general. Will be referred to the Technical Committee page for details.

The SCSI standards define the electrical parameters of the input-output interfaces. Standard SCSI-1 date of 1986, he defined standard commands that control SCSI devices on a bus clocked at 4.77 MHz with a width of 8-bit, allowing him to offer speeds of the order of 5 MB/s.

However a large number of these orders were optional, that's why in 94 standard
SCSI-2 was adopted. It defines 18 commands called CCS (Common Command Set). Various versions of the SCSI-2 standard have been defined :

-The Wide SCSI-2 is based on a 16-bit width (instead of 8) bus and allows us to offer a rate of 10 MB/s;
-Fast SCSI-2 is a fast synchronous mode allowing to spend 5 to 10 MB/s for the standard SCSI, and 10 to 20 MB/s for Wide SCSI-2 (named for the occasion Fast Wide SCSI-2);
-Fast-20 and 40 Fast modes allow respectively to double and quadruple those flows.

The SCSI-3 standard includes new commands, and allows chaining of 32 devices as well as a maximum of 320 MB/s (Ultra-320 mode).

The following table summarizes the characteristics of the different SCSI standards :