ZyXEL Elite 2864 User Guide - Page 240

EEPROM: An Electronically Erasable and Programmable Read Only Memory. Such a device is used in ZyXEL modems to store settings and profiles. An EEPROM does not lose data when the modem is turned off. EIA: Electronic Industry Association (of North America); this organization was the first to draft a standard serial port (RS-232C). EPROM: Electrically Programmable Read Only Memory. A memory chip which may be programmed electronically, but must be exposed to ultraviolet radiation to be erased. Error correction: A method to compensate for errors which occurred in the transmission path. Error correction is done by the modems and is transparent to the DTEs. The most familiar correction methods are MNP5 and V.42bis. Fax: Long distance copy; facsimile - transfer of graphical data between two fax units. The graphical data is compressed during transfer (G3). FIFO-Buffer: First-in-first-out buffer. A buffer of this type is used in the 16550 type UARTs which allow higher data throughput rates on PCs. Firmware: The ZyXEL modems' system software is located in flash EPROMs. Depending on the size of the EPROM(s), some features may or may not be available. Flash: See Hook-Flash. Flow control: Method to stop and start the data flow to avoid loss of data. Front panel: The front panel on the ZyXEL modems consists of LED indicators and key switches. Some models also feature a 20 × 2 liquid crystal display (LCD). FSK: Frequency Shift Keying - a frequency modulation scheme. G3 fax: Several fax standards exist. Most available fax machines use the group 3 (G3) standard. This standard defines the compression of graphic data and a transmission speed of up to 14400 bps with an automatic fallback to 2400 bps if the telephone line is bad. Handshake: At the beginning of a connection, the modems must negotiate and initialize the protocols to be used and the speed at which the connection is to be established. This negotiation phase and the following initialization phase is called handshake. HDLC: High-level Data Link Control - protocol for synchronous transfer. Highspeed modem: A modem that works at bit rates higher than 9600 bps. Hook-Flash: The hook-flash is a signal used in a dial sequence. This signal may be used for call transfers or to request an outside line on certain PABX. Hz: Hertz, the unit of frequencies. Interrupt: In a computer, some tasks must be performed regularly and without delay. This is possible because the CPUs provide special interrupt vectors. These vectors Glossary-4