Content area
Full text
The Small Computer Systems Interface (SCSI) was originally defined as a universal parallel, system-level interface for connecting up to eight devices along a single cable, called the SCSI bus. SCSI is an independent and intelligent local I/O bus through which a variety of different devices and one or more controllers can communicate and exchange information independent of what the rest of the system is doing.
The parallel SCSI interface has a product depth and breadth that exceeds any other I/Ointerface. SCSI is supported by a wider variety of peripherals than any other type of interface. The list of supported peripherals includes tape drives, optical drives, hard disk drives, scanners, printers, disk array subsystems (RAID) and CD-ROM drives. This vast array of products, coupled with the maturity and proven performance of parallel SCSI, make it very difficult for any new peripheral interface to garnish enough clout or gain enough market share to begin to compete successfully with parallel SCSI. Even if such an interface were developed, issues such as interoperability with existing devices, backward compatibility and the support infrastructure required to address field problems preclude such a change. There are currently more than 120 computer, subsystem and peripheral manufacturers that rely on parallel SCSI for their interconnect requirements.
The fact that parallel SCSI supports such a broad base of peripherals and applications is no accident. The interface was created with the goal of making a common interface that could be used across all peripheral platforms and system applications. No other interface can address as wide a range of applications or has a command set broad enough to support the multitude of peripherals supported by SCSI. In addition, the parallel SCSI interface allows systems equipped with this interface to perform to their maximum potential because the I/O is not the system bottleneck.
Some Parallel SCSI advantages are:
* multitasking;
* low overhead;
* high bandwidth;
* extensive connectivity;
* small form factor interconnect; and
* high velocity cable
In addition, a powerful feature of SCSI is command queuing. Command queuing mechanisms are becoming widely used in desktops using Windows NT. This is a powerful performance advantage over ATA.
For many reasons, SCSI continues to offer computer and peripheral manufacturers the best I/O choice, allowing them to deliver...