User's Manual

5634BIF User’s Manual

I/O Port (JS2) Setting

IRQ (JS3,JS4&JS5) Setting

Short Open

Figure 1-2. Jumper diagram

As Table 1-1 shows, a serial device configured to use COM1 will conflict with another

serial device configured to use COM3 which happen to select IRQ4, because these ports

share the same interrupt. To avoid this conflict, one of device should use COM4. Similarly,

a serial device on COM2 will conflict with a serial device using COM4, because these

ports share the same interrupt (IRQ3). In this case, one of the devices should use COM3.

Whichever COM port setting you use, make sure the software you are using is set up to

address that port.

For maximum flexibility, your modem supports IRQ2-5 interrupt requests. Typically, you

will use IRQ3 or IRQ4. However assume your PC has a serial printer configured as COM1

and serial mouse configured as COM2. If you want to use your modem while printing in

the background, you cannot set the modem to COM3 (which uses IRQ4) because the

IRQ4 setting for COM3 conflicts with the printer using COM1, which also uses IRQ4.

Setting the modem to COM4 (IRQ3) conflicts with the mouse using COM2 (IRQ3).

To solve this problem, you can use Jumper 1(JP1) to select IRQ2 or IRQ5( refer to table

1-1). This means that you can print in the background using a printer configured as COM1,

use a mouse configured as COM2, and perform modem activities all at the same time!

IRQ settings 2 through 5 should be used only if you have no other choice. Not all PCs and

DOS versions support IRQ5. IBM PC/AT computers and compatibles should be able to

use IRQ2 or IRQ5, so long as the computer does not have a parallel port set up as LPT2

or another device that is using IRQ2.