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"Illegal Instruction NPX Attempted" Error Run
DocumentID: 614918
Revision Date: 29-Feb-96 1:36:37 PM

The information in this document applies to:
WordPerfect® 5.1 for DOS

Problem

Symptoms: The error "Illegal Instruction NPX Attempted" occurs while running WP 5.1 DOS under OS/2. This error message usually occurs when a user is trying to print from WP 5.1. Solutions: The NPX instruction is not supported on some 80286/SX or higher machines. Installing the VNPX.SYS to the OS/2 CONFIG.SYS will allow SX machines to run programs which attempt to access the NPX instruction. The VNPX.SYS intercepts the error and handles it so the program continues to run.

How/Why:
Apparently Lotus 1-2-3 for DOS was causing the same error when running under OS/2. Lotus and IBM worked together and found that the 1-2-3 code assumes that all 486 machines have a built in math coprocessor. On a 486SX, Lotus 1-2-3 called NPX, a math coprocessor instruction that is not supported on SX machines. Lotus changed the 1-2-3 code to solve the problem. IBM came out with a workaround (VNPX.SYS) for Lotus users who do not have the latest 1-2-3 code. This device driver ships with OS/2 2.1 and the OS/2 2.0 service pack. VNPX.SYS captures any relevant instructions and then emulates a math coprocessor. Whether or not WP 5.1 DOS actually uses the NPX instruction, OS/2 thinks it does. Loading the VNPX.SYS driver in the CONFIG.SYS might avert the error message.

Answer:

Details:


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