3Com 56K manual Glossary

GLOSSARY 9

originate mode A state in which the modem transmits at the predefined low frequency of the communications channel and receives at the high frequency. The transmit/receive frequencies are the reverse of the called modem which is in Answer mode.

parallel transmission The transfer of data characters using parallel electrical paths for each bit of the character, for example, 8 paths for 8-bit characters. Data is stored in computers in parallel form, but may be converted to serial form for certain operations. See Serial Transmission.

parity An error-detection method that checks the validity of a transmitted character. Character checking has been surpassed by more reliable and efficient forms of block-checking, including Xmodem-type protocols and the ARQ protocol implemented in modems.

The same type of parity must be used by two communicating computers, or both may omit parity. When parity is used, a parity bit is added to each transmitted character. The bit's value is 0 or 1, to make the total number of 1's in the character even or odd, depending on which type of parity is used.

Plug & Play ISA A variation of the standard ISA bus that attempts to automate the troublesome process of resolving the IRQ and COM port conflicts that can arise when new devices are installed in ISA-bus computers.

Point-to-PointA protocol used to send data over serial lines. PPP provides error Protocol (PPP) checking, link control, and authentication, and can be used to carry IP,

IPX, and other protocols. PPP is superseding SLIP as the leading dial-in protocol.

protocol A system of rules and procedures governing communications between two or more devices. Protocols vary, but communicating devices must follow the same protocol in order to exchange data. The format of the data, readiness to receive or send, error detection and error correction are some of the operations that may be defined in protocols.

provisioning Another way of saying "setting up telephone lines."

RAM See Random Access Memory.

Random Access Random Access Memory. Memory that is available for use when the Memory (RAM) modem is turned on, but that clears of all information when the power

is turned off. The modem's RAM holds the current operational settings, a flow control buffer, and a command buffer.