IBM 300 Service Manual

Also see for SurePOS 500: Technical reference Configuration guide User guide

Contents

and coding between a data terminal equipment (DTE)and a line. A DCE can be separate piece of equipmentor part of other equipment.data terminal equipment (DTE). That part of a datastation that serves as data source, data sink, or both,and provides the data communication control functiondepending on the type of protocol used.dB. Decibel.dBm. Decibel based on 1 milliwatt.DC48. Dc power input type -48Vdc. Direct current.DCD. Dc distribution (module).DCE. Data circuit-terminating equipment.DDI. Direct dialing-in.DE. Discard eligibility.decibel (dB). (1) One tenth of a bel. (2) A unit thatexpresses the ratio of two power levels on a logarithmicscale. (3) A unit for measuring relative power. Thenumber of decibels is 10 times the logarithm (base 10)of the ratio of the measured power levels; if themeasured levels are voltages (across the same or equalresistance), the number of decibels is 20 times the logof the ratio.decibel based on 1 milliwatt (dBm). A unit ofabsolute power measurement that is scaled such that 0dBm equals 1 milliwatt.dialog box. On the screen of a station, an area withentry fields and push buttons. (Also called dialog.)DLCI. Data link connection identifier.DNPT. Destination numbering plan table.DSP. Digital service processor.DSU. Data service unit.DTE. Data terminal equipment.DTMF. Dual-tone modulation frequency.DTR. Data terminal ready.dummy module. In an Nways Switch, a cover insertedin the place of a module to ensure correct air coolinginside a logic subrack. During normal operation, thedummy modules must not be removed.E1 standard. A European standard for TDM digitaltransmission service at 2.048 Mbps.E3 standard. A European standard for TDM digitaltransmission service at 34.368 Mbps. An E3 line cantransport up to 16 E1 circuits.E&M. Earth & mark.ECMA. European Computers ManufacturersAssociation.EIA. Electronics Industries Association.equivalent capacity. The minimum amount ofbandwidth needed by a connection to ensure that thepacket loss ratio is below a specified threshold.ESF. Extended status flags.ETS. European telecommunication standard.FANB. Fan box.FAT. File allocation table.fax. Document received from a facsimile machine.Synonym for telecopy.FCS. Frame check sequence.FDDI. Fiber Distributed Data Interface.FE1. Fractional E1.FECN. Forward explicit congestion notification.FEP. Front-end processor.fiber. Synonym for optical fiber.fiber budget. The optical power loss as result of thenumber of connections in the optical fiber linksubtracted from the working budget. The loss as aresult of connections includes connector loss and spliceloss. The fiber budget is expressed in decibels.Fiber Distributed Data Interface (FDDI). A U.S.standard for 100 Mbps token-ring LANs using opticalfiber cables over distances of several kilometers.fiber optic cable. Synonym for optical fiber.FR. Frame relay.FRAD. Frame-relay access device.frame relay (FR). A connection-oriented protocol totransport data frames over a fast packet-network withguaranteed end-to-end quality of service.FRFH. Frame-relay frame handler.front-end processor (FEP). A processor, such as theIBM 3745, 3746 Model 900 or 950, or 3174, thatrelieves a main frame from communication controltasks.Glossary E-3