USRobotics V.34 - Manual (Page 30)

COURIER HIGH SPEED MODEMS
Internal Modem Set Up 3-3
If you're only using COM1 for a device, you can skip this sec-
tion except for
DIP Switches, just before Installing the Modem. If
you've already installed devices at both COM1 and COM2, you
will have to select either COM3 or COM4. Carefully review the
following section for complete instructions.
Select a Serial Port
WARNING: If you are going to use COM1, COM3, or COM4,
you must change some switches on the modem board, called
jumpers. First, you need to select the correct Interrupt Request
(IRQ) to use at that serial port. Peripheral devices use IRQs to
instruct the computer to stop the processor's current operation;
this allows the devices to perform their operations.
Using COM1, 2, 3 or 4 depends on your equipment's configura-
tion, as described below. Remember which serial port you
assign to the modem, because you must specify it to your
communications software later. The table in the next section
includes hexadecimal addresses, required by some software.
COM1: You may use this port if the computer does not have an
installed serial connector at COM1. (This situation is unlikely.)
You will have to modify some switches on the modem, so be
sure to read this entire section of the chapter. However, you
may prefer to leave the modem set to COM2 and proceed to
DIP Switches, just before the installation instructions.
COM2: If your computer is equipped with one serial connector
at COM1, and if you are not already using COM2 for another
device, use this port. (This is the most common configuration.)
Since the modem is already set to operate at COM2, skip the
rest of this section and proceed to
DIP Switches, just before the
installation instructions.
COM3, COM4: If you have two serial devices that already use
COM1 and COM2, you can set the modem for either COM3 or
COM4. Review your communications software documentation
to be sure your program supports these additional serial ports.
(Most programs do.) If your software doesn't, you will have to
remove one of the other devices.