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Configuring Express Communications Settings for Modems that Use Non-Standard Interrupts
 

As users add more peripherals to their systems, it is possible that the standard com port IRQ's 4 and 3 may not be available for Com 3 and 4. In that case, it is not unusual for IRQ 5 ( or others ) to be used.

The easiest solution to try is to configure Express for Windows™ for the proper Com Port and then set the Protocol as Polled.  In many cases this will allow modems with non-standard IRQs to work with Express.  However, if this does not work, Express allows for the insertion of information regarding the non-standard IRQ.

The Non Standard setting is on the Communications | Settings | Options tab ( pictured below ). This setting can be changed when the modem is installed using an IRQ other than that which is standard for the port specified.

Standard IRQ's are:

Com 1 - IRQ 4
Com 2 - IRQ 3
Com 3 - IRQ 4
Com 4 - IRQ 3

The base addresses for each Com Port are:

Com 1 - 0x3F8
Com 2 - 0x2F8
Com 3 - 0x3E8
Com 4 - 0x2E8

For a modem on Com 3, IRQ 5 - the Non Standard setting would be 5,0x3E8. With 5 specifying the IRQ and 0x3E8 being the base address for Com 3

The form for the Non Standard is N,0x??? where N is the IRQ number and 0x??? is the base address for the port. Another example would be Com 4, IRQ 9:

Non Standard would be: 9,0x2E8
 

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