Was (wer) ist SCSI-2 - definition

ORIGINAL SCSI COMPUTER STORAGE BUS

SCSI1; SCSI-1; SCSI-2; SCSI2; SCSI-3; SCSI3; Fast SCSI; Wide SCSI; Ultra SCSI; Narrow SCSI; LVD SCSI; Ultra-160; Ultra SCSI-2; Ultra SCSI-3; Ultra-320; Ultra-640; Fast-320; Differential SCSI; Ultra-3; Ultra-2; SCSI Parallel Interface; Ultra2 SCSI; SCSI terminating resistor; Scsi terminating resistor; Quick arbitration and selection

SCSI-2

<hardware> A version of the SCSI command specification. SCSI-2 shares the original SCSI's asynchronous and synchronous modes and adds a "Fast SCSI" mode ( < 10MB/s ) and "Wide SCSI" (16 bit, < 20MB/s or rarely 32 bit). Another major enhancement was the definition of command sets for different device classes. SCSI-1 was rather minimalistic in this respect which led to various incompatibilities especially for devices other than hard-disks. SCSI-2 addresses that problem. allowing scanners, {hard disk drives}, CD-ROM drives, tapes and many other devices to be connected. Normal SCSI-2 equipment (not wide or differential) can be connected to a SCSI-1 bus and vice versa. (1995-04-19)

Wide SCSI

<hardware, standard> A variant on the SCSI-2 interface. It uses a 16-bit bus - double the width of the original SCSI-1 - and therefore cannot be connected to a SCSI-1 bus. It supports transfer rates up to 20 MB/s, like Fast SCSI. There is also a SCSI-2 definition of Wide-SCSI with a 32 bit data bus. This allows up to 40 megabytes per second but is very rarely used because it requires a large number of wires (118 wires on two connectors). Thus Wide SCSI usually means 16 bit-wide SCSI. (1995-04-21)

Fast SCSI

<hardware> A variant on the SCSI-2 bus. It uses the same 8-bit bus as the original SCSI-1 but runs at up to 10MB/s - double the speed of SCSI-1. (1994-11-24)

Wikipedia

Parallel SCSI

Parallel SCSI (formally, SCSI Parallel Interface, or SPI) is the earliest of the interface implementations in the SCSI family. SPI is a parallel bus; there is one set of electrical connections stretching from one end of the SCSI bus to the other. A SCSI device attaches to the bus but does not interrupt it. Both ends of the bus must be terminated.

SCSI is a peer-to-peer peripheral interface. Every device attaches to the SCSI bus in a similar manner. Depending on the version, up to 8 or 16 devices can be attached to a single bus. There can be multiple hosts and multiple peripheral devices but there should be at least one host. The SCSI protocol defines communication from host to host, host to a peripheral device, and peripheral device to a peripheral device. The Symbios Logic 53C810 chip is an example of a PCI host interface that can act as a SCSI target.

SCSI-1 and SCSI-2 have the option of parity bit error checking. Starting with SCSI-U160 (part of SCSI-3) all commands and data are error checked by a cyclic redundancy check.

https://en.wikipedia.org/wiki/Parallel SCSI