Atari XM301 Owner's Manual page 41

Direct-Connect Modem A modem (MOdulator-DEModulator) con¬
nected directly to the phone system for use in data transmission
Contrast with acoustic coupler.
Download/Upload The process of transferring and saving a program
over telephone lines. Downloading refers to transferring a program
from a central computer to a remote terminal. Uploading sends a
program from a remote terminal to a central computer. Many
bulletin board systems make programs and games available to
callers through downloading. Callers to BBS's, on the other hand
often donate programs they've developed for the BBS by
uploading.
Full-Duplex Data transmission in both directions simultaneously.
Can be likened to a phone conversation in which both parties can
talk at the same time.
Half-Duplex Data transmission in both directions, but only one
direction at a time. Can be likened to a CB conversation in which
both parties can talk, but only alternately.
Handshaking Protocol An exchange of predetermined signals by
modems and their respective terminals when a connection is
established. Modems can "handshake" and transfer data only if
they are similarly configured —for example, at 300 bps full-duplex
transmission. K
Mark The signal equivalent of a binary 1 (i.e„ the presence of a
signal).
Modem See Direct-Connect Modem and Acoustic Coupler.
Parallel Transmission A method of data exchange which transmits
all the bits comprising a character or word simultaneously.
Imagine all the bits marching abreast.
Parity Bit A bit added to a group of bits to make the total of all bits
odd or even.
Public Domain Software Software that is not protected by
copyright laws and is therefore free for all to reproduce.
RS232C A set of standards developed by the Electronics Industry
of America (EIA) that standardizes the interface requirements
between modems and data terminal equipment.
Serial Transmission A method of data exchange in which each bit
of a character is sent sequentially rather than simultaneously as in
parallel transmission. Imagine the bits marching in single file.
Space Signal equivalent of a binary 0 (i.e„ the absence of
a signal).
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