Multi Tech Equipment ISIHI-2S manual 174

Glossary

ing contributions in electronics, and sets electronic interface standards, such as RS-23.

EISA (Enhanced Industry Standard Architecture - pronounced “eesa”) : The purpose of the EISA bus was to provide a 32-bit bus for faster throughputs while maintaining backward compatibility with the classic ISA bus architec- ture.

Emulation: The process of one type of device imitating another via a hardware or software package. Terminal emulation, for example, allows a PC to access a mainframe computer by generating and accepting data like a “dumb” terminal.

Environment: A computer configuration that includes the CPU model and system software (operating system, data communications and database systems). It may also include the programming language used. It sets the stan- dards for the applications that run in it.

EPROM (Erasable Programmable Read Only Memory - pronounced “eeprom”) : A reusable PROM chip that holds its contents until erased under ultraviolet light.

Error correction: The process of detecting distorted data bits and requesting a retransmission or interpretation to correct the error. Errors are introduced by bad line condi- tions or external interface.

F

Fax (facsimile): Refers to the bit-mapped rendition of a graphics-oriented document (fax) or to the electronic transmission of the image over telephone lines (faxing). Fax transmission differs from data transmission in that the former is a bit-mapped approximation of a graphical docu- ment and, therefore, cannot be accurately interpreted according to any character code.

Fax card: An expansion card that, with the appropriate software, allows a PC to operate as a fax transmitter/ receiver. PC fax cards may be able to send and receive faxes from a file on the PC. If an external scanner is avail- able, the PC can also transmit the scanned image via the fax card.

Fax/Data-Modem: A multifunctional device capable of transmitting either data or faxes. It is available as an external unit or expansion board. It includes a fax switch that routes the call to the fax or the data modem.

Fax server: A network resource that allows workstation PCs to transmit faxes as though the PC had an internal fax card or a fax modem attached.

Firmware: A category of memory chips that hold their content without electrical power. They include ROM, PROM, EPROM, and EEPROM technologies. Firmware becomes “hard software” when holding program code.

Flash Memory: A memory chip that holds its content without power, but must be erased in bulk. The term comes

from its ability to be erased “in a flash”. Flash memory is derived form EEPROM, but are less expensive and provide higher bit densities.

Floppy Disk: Also called a diskette. It is a round disk with a hole in the middle, made of flexible material and houses in a square envelope or cartridge. A disk drive holds the floppy disk through the hole in its center and spins it within its envelope. They can be used over and over again. Contrast with hard disk.

Flow control: The process of regulating the speed at which data enters or leaves a serial port. Software flow control is implemented by communications software or by the user sending predefined characters or packets which are recog- nized as “pause” and “resume” indicators. Hardware flow control is achieved by using the RTS (request to send) and the CTS (clear to send) control lines of the RS-232 inter- face.

Footprint: The desk or floor space that a piece of hardware occupies. Also referred to as “real estate”.

Foreground: The application program currently running on, and in control of, the PC screen and keyboard. The area of the screen that occupies the active window. Compare with background.

Format: 1. The way text is set up on a page.

2.To prepare a disk for holding information. Formatting a disk can delete all information on it.

3.The information is structured in a file, often specific to one application or protocol.

Frequency: A characteristic of an electrical or electronic signal which describes the periodic recurrence of cycles. Frequency is inversely proportional to the wavelength or pulse width of the signal.

FSK (Frequency Shift Keying): A technology that estab- lishes two frequencies used to represent binary values. This was the earliest type of modulation used by 300 bps modems.

Full-duplex: A method of transmitting and receiving data simultaneously over a single pair of wires. Compare with Half-Duplex.

G

Gateway: A workstation, which serves as a protocol con- verter (translator) between two or more dissimilar networks, providing incompatible systems.

H

Half-Duplex: The transmission of data in both directions, but only one direction at a time. Compare with Full-Duplex.

Handshaking: A process that two modems go through at the time of call setup to establish synchronization over the data communications link. It is a synchronization and negotiation process, accomplished by the exchange of predefined, mutually recognized control codes.

174 MultiModem ISI Hybrid Series, ISIHI-2S