The 68LC040 CPU chip has a bug in it which prevents SoftwareFPU from working properly with many programs. There is no work-around for this bug. If you have SoftwareFPU installed on a 68LC040 machine (such as the Centris 610, Quadra 605 and 610, LC 475, and Performa 475 & 476), be sure to test any FPU-depedent software thoroughly before relying on it. If the software crashes, it is probably because of the CPU bug. To determine for sure whether the CPU bug or another problem is causing the crash, run same application on a regular 68040 Macintosh. If the application operates correctly on a 68040 machine, the CPU bug is causing the application to crash on the 68LC040 machine. If the program crashes on the 68040 machine, the CPU bug is not the cause of the problem.
Motorola is readying a revised version of the 68LC040 CPU which supposedly has the CPU bug fixed. The new version should be available sometime in Q2 1994. The revised CPU will have a mask revision number of 03E23G or higher. To check the mask revision of the CPU in your Macintosh, open your Macintosh (check to make sure you are not voiding your warranty first), and locate the 68LC040 chip. The mask revision number is printed on the top of the chip, on the second line. The mask revision number reads from left to right, and each series of numeric or alphabetic characters is a different field. Reading left to right, if any of the fields are less than the corresponding field in 03E23G, your CPU has the bug that affects SoftwareFPU.
If your program crashes because of the 68LC040 CPU bug, your options are to a) replace your software with a version that does not require an FPU, b) upgrade your Macintosh with a hardware FPU, or c) replace your CPU chip with the revised chip (when available) that does not have the bug.
