US Robotics COURIER - CHAPTER 3. QUICK START-ASYNCHRONOUS OPERATIONS; Initial Modem Settings

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COURIER HIGH SPEED MODEMS
CHAPTER
3. QUICK START-ASYNCHRONOUS OPERATIONS
ASYNCHRONOUS/SYNCHRONOUS COMMUN/CATIONS
Courier high speed desktop and rack modems are capable of
asynchronous and synchronous communications. Terminals are
usually capable of one type of communications or the other. The
typical personal computer, however, is equipped to communi-
cate only asynchronously.
Most of the operational information in this manual is organized
around asynchronous communications. During asynchronous
communications, the computer adds Start and Stop bits to each
data character before sending it to the modem over the serial
port, and expects received data to be in the same format.
Synchronous data transfer is based on synchronized timing
between two communicating devices, not on data format, and is
usually required by mainframes and other large computers. To
exchange
data synchronously, a personal computer requires
specialized equipment, including the installation of a
synchronous communications card with a synchronous port. If
you will be making synchronous connections, you'll find the
modem easy to use. Just follow the instructions in Chapter 7.
INITIAL MODEM SETTINGS
This manual covers the operation of three Courier models, the
Courier HST Dual Standard, Courier V.32 bis, and Courier HST.
The
modems are factory-set for compatibility with their own
type of modem.
• Dual Standard modems-BO-so that they connect at
high speeds with both V.32 bis and HST modems
• V.32 bis modems-BO-to connect at high speeds with
V.32 bis and V.32 modems
• HST modems-Bl-to connect at high speeds with HST
modems
The above settings do not affect how the modems connect at
speeds of 2400 bps and below. Leave the modems set to their
factory defaults, BO or Bl. The exception is when an HST
modem is to answer overseas calls, in which case you should set
it to BO.
Quick Start 3-1