Digital Equipment 300 Series AXP Reference Manual page 297

SCSI bus
A communications pathway between the Small Computer System
Interface (SCSI) and other internal devices. The SCSI bus
consists of an address bus, which selects the location of the data,
and a data bus, which transfers the data.
SCSI controller
The device that directs the operations of the Small Computer
System Interface (SCSI) with synchronous and asynchronous
capabilities.
SCSI ID
The switch or jumper setting that identifies the address of each
device installed on the system. Each device must have a unique
SCSI ID for proper communication between the system and the
device.
SCSI jumpers
Removable electrical connectors on some of the drives, such as
the RRD42, that are set to determine the SCSI ID on a drive.
Each installed drive must have a unique setting for proper
communication between the system and all drives.
SCSI switches
Electrical switches on the side or back of some drives, such
as the RX26, that determine the SCSI setting of the drive.
Each installed drive must have a unique setting for proper
communication between the system and all drives.
secure system jumper
An electrical jumper in the system unit that you can move so
that the system is accessible to only those with the correct
password.
self-test
A test that is invoked automatically when the system starts up.
Serial Communication Controller (SCC)
The DEC 3000 Model 300 Series AXP I/O subsystem includes
two SCC chips that control the mouse, keyboard, and serial
communications.
Glossary–25