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5. What about the 680LC40's?
This little chip can be quite a problem for the uninformed. If you have one of these chips, you may have a defective one that does not support any kind of FPU (floating-point) emulation. According to Motorola's official errata, any chip with a mask revision less than 2E71M has the bug. Specifically, revision 2E23G, used in the LC 475, has been confirmed to be buggy. Running Linux on one of these machines is possible, but probably not worth it. You'll need to recompile all of your binaries not to use floating point (gcc's -m-soft-float option works nicely) and you'll need to hack your kernel to cause it not to try to save FPU register states while task-swapping. All in all, a hellish task and probably not worth it. At one point, it was possible to get a replacement from Apple and/or Motorola, but that was quite a long time ago, and given Apple's present state of complete disassociation from the 68k Macs, your best bet would be simply to upgrade to a real 68040. Sorry.
Note: Although not tested it is believed that those chips cannot be used in multiuser machines that have even the slightest fear of hacking. It makes a very easy method for your machines to be crashed solid and there is no workaround.
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