Help! I have a IIGS with a stock zip chip that, until recently, would pass the GS self test, but now fails with SYSTEM BAD 05012A00 if I put in the stock 65c816 all is good the switch 4 setting on bank 1 of the Zip has no effect on this Could someone maybe tell me what the error code means, so I can begin to troubleshoot, or do I just try to find another ZipChipGS?