IBM iSeries 270 Service Manual page 608

EMI Electromagnetic interference.
EPO Emergency power-off.
ERC Extended reference code
ESD Electrostatic discharge.
expansion unit
An expansion unit contains I/O hardware such as cards, tapes and disk units. The system may
have multiple expansion units.
An expansion unit can be bolted directly to the side of a system unit and is contained within the
system unit covers.
An expansion unit can also be mounted on top of a rack or tower and has its own covers.
Internal signal cables interconnect the expansion unit to the system unit, rack, or tower.
FAX Facsimile machine.
FC Feature code.
FDS Flexible distribution system.
FRU Field-replaceable unit.
GND Ground (electrical).
Guest partition
This is a secondary partition which is running an operating system other than OS/400. The guest
partition requires another partition to host it. The purpose of the hosting partition is to supply paths
from virtual I/O in the guest partition's operating system to real I/O hardware drivers in the hosting
partition. The guest partition requires a console in order to provide an interface to DST console
functions. TELNET is used to establish a guest console from the hosting partition. The guest
partition's console should not be confused with the console used by the operating system running
in the guest partition. They are separate console sessions.
high-speed link (HSL)
A hardware connectivity architecture that links system processors to input/output processors
(IOPs) and other system units.
Hosting partition
This is a partition, either the Primary or a secondary partition that is not a guest partition. The
hosting partition has the real I/O devices that the virtual I/O device drivers in a guest partition
connect to. The hosting partition also supplies the guest partition's DST console session, via a
TELNET connection into the hosting partition. The guest partition's console is not part of the
hosting partition's console. The host partition's console, the guest partition's console session and
the guest partition's operating system's console are all different console sessions.
HSL Ring
High Speed Link Ring (shown as "System Interconnect" on the display). This is a logical ring of
HSL connections originating from the HSL Controller of a processor unit, sequentially connecting
I/O or other processor units and ending back at the HSL Controller where the ring originated.
ID Identification.
input/output processor
A device that processes programmed instructions and controls one or more I/O devices or
adapters.
I/O Input/output.
IOA Input/output adapter.
596
Hardware (Remove and Replace; Part Locations and Listings)