SCSI-90°DIP Section

Small computer system interface (SCSI) is an independent processor standard for system level interfaces between computers and intelligent devices (hard disks, floppy drives, optical drives, printers, scanners, etc.). SCSI is an intelligent universal interface standard.

The last SCSI device in the SCSI chain uses a terminator, and the intermediate device does not need a terminator. Once the terminator is used by the intermediate device, the SCSI card cannot find the future SCSI device. If the last device does not use a terminator, SCSI will not work properly. Terminator is composed of resistors, located at the end of the SCSI bus, to reduce the mutual influence of the signal, maintain the constant voltage on the SCSI chain.

Most of the SCSI devices have built-in terminators and use a jumper to control on / off. The SCSI device is highly intelligent and can automatically control the terminator on / off. For example, if a hard disk is connected to a CD-ROM, the CD-ROM can work normally regardless of whether the terminator of the hard disk is on or off. However, when two hard disks are connected, the situation becomes more complicated. Before two Seagate hard disks are connected, one hard disk terminator must be off. Before a Seagate hard disk is connected to a quantum hard disk, a hard disk terminator can work normally regardless of whether it is on or off.