Sunday, July 4, 2010

I’ve just installed a Creative Labs AWE64 soundcard in my PC ...

Q I’ve just installed a Creative Labs AWE64 soundcard in my PC (running Windows 98) so that I can send and receive slow-scan TV (SSTV). The performance has been very erratic to say the least. Reception is terrible or nonexistent, and when I transmit I’m told that I only send a brief burst of sound, then nothing. I’ve looked into every possible problem and I’m at the end of my rope. Can you help?

A Are you sure you’ve looked into every possible problem? The Doctor has seen this gremlin before and the cause is almost always an interrupt (IRQ) conflict within your PC. The AWE64 uses IRQ 5 or 7, with five being the default. If you have any other devices that are using these IRQs, Windows will attempt to assign an unused IRQ to the soundcard. That seems reasonable until you realize that the AWE64 is still expecting to use IRQ 5. Do you see what’s going on? The AWE64 is attempting to address the processor using IRQ5, but that particular “highway” is already busy. The result is a classic IRQ conflict and some screwy operation to go along with it.

Use the Windows “Device Manager” to carefully examine your system. It can list all of the available IRQs and tell you which devices are using them. Then, you can reassign the IRQs as necessary.

Update: The Doctor scores again! A PS-2 mouse has been inadvertently assigned to IRQ 5 and the AWE64 was given IRQ 9. A quick switcheroo and all is well!

From QST October 1999