Fixes for the "Unknown Exception" bug in SimCity 3000

Contributor/author(s): No.6, Ben Turner, Jason Harris

The "Unknown Exception" bug is possibly caused by IRQ sharing between the video and audio adapters in a system, most commonly systems with AGP video and PCI audio.

Users experiencing the crash bug or "??? Unknown Exception" bug are advised to check their Device Manager (right-click My Computer, click Properties, Device Manager tab, tree item My Computer, click Properties button) to ensure that their video and audio cards are not sharing an IRQ.

Although shared IRQs are fine under many circumstances, the intensive nature of SC3K's sound and graphics cause problems if the IRQs are shared.

Most motherboards with AGP video only allow some of their PCI slots to allocate an IRQ; the rest share IRQs. Users should check with their computer manufacturer or motherboard maker for detailed instructions. (On the ABit BH6, only PCI slots #2 and #3 support IRQs).

Another suggestion was sent in by Ben Turner, suggesting that the problem might lie with the processor:

In spite of the previous suggestion, I used to get the "??? Unknown Exception" error all the time, in spite of having no shared IRQs. I was, at the time, using a Cyrix 6x86 processor. After upgrading to an AMD K6-III, that error never recurred. I know the old Cyrix chips weren't 100% Pentium-compatible; it rarely causes problems, but in this case, it was certainly the problem. Anyone using a Cyrix chip, especially, the older ones, should consider it a possible culprit if you've already tried resolving any IRQ-sharing on your system.

One other suggestion from Jason Harris is to reinstall DirectX, or better yet, install the latest version of DirectX (currently version 7.0). The latest version can be found at the Microsoft Web site (http://www.microsoft.com).

See also
Unknown Exception error: suggestion