TITLE
    Macintosh: Unimplemented Trap Error Message Explained (11/95)
Article ID:
Created:
Modified: 		18999
11/30/95
12/1/95
TOPIC


    This article describes what a trap is in the Mac OS. It also explains why you might occasionally get an "Unimplemented Trap" error message.

DISCUSSION


    The Macintosh operating system (Mac OS) operates by using a series of interrupts to perform an operation. When an application draws a line, for example, it sends a specially encoded instruction to the microprocessor. The microprocessor decides if this is one of the 200+ fundamental instructions that are part of the microprocessor, if it is not, it calls a software routine called a "trap dispatcher". This routine then calls a software routine (usually in ROM) which draws the line.

    If the instruction received by the microprocessor is improperly formatted, but appears to have the characteristics of a trap, it still sends it to the trap dispatcher. If the trap dispatcher cannot handle it, then you get an unimplemented trap message.

    While unimplemented trap errors can be spurious and caused by software. If you get this error message consistently performing a function on your Macintosh, it could be a real software related error. When you consistently get unimplemented trap errors, you should look at the software on your hard disk since it could be corrupted, or incompatible. Software issues can result from the use of incompatible or corrupt third-party drivers, control panels, or extensions. But, these errors are not limited to third-party products, they can also result from the use of corrupted system software.

    To correct these problems, you should remove the third-party extension, control panel, or application, or reinstall your system software.


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Document Information
Product Area: Mac OS System Software
Category: General OS
Sub Category: General Topics
Keywords:

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