Compaq HSZ80 manual Dual-simplex, See ECB

	GL–5
dual-simplex	A communications protocol that allows simultaneous transmission in both
	directions in a link, usually with no flow control.
DUART	Dual Universal Asynchronous Receiver and Transmitter. An integrated
	circuit containing two serial, asynchronous transceiver circuits.
ECB	External Cache Battery. The unit that supplies backup power to the cache
	module in the event the primary power source fails or is interrupted.
ECC	Error Checking and Correction.
EDC	Error Detection Code.
EMU	Environmental monitoring unit. A unit that provides increased protection
	against catastrophic failures. Some subsystem enclosures include an EMU
	which works with the controller to detect conditions such as failed power
	supplies, failed blowers, elevated temperatures, and external air sense faults.
	The EMU also controls certain cabinet hardware including DOC chips,
	alarms, and fan speeds.
ESD	Electrostatic discharge. The discharge of potentially harmful static electrical
	voltage as a result of improper grounding.

extended subsystem A subsystem in which one or two cabinets are connected to the primary cabinet.

external cache	See ECB.
battery
failedset	A group of failed mirrorset or RAIDset devices automatically created by the
	controller.
failover	The process that takes place when one controller in a dual-redundant
	configuration assumes the workload of a failed companion controller.
	Failover continues until the failed controller is repaired or replaced.

Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide