============================================================================= AST RESEARCH, INC. TECHNICAL BULLETIN #0654 12-21-90 ============================================================================= PREMIUM 386/16 WITH MATH CO-PROCESSOR Erratic operation may occur when using a math co-processor in the Premium 386/16. This condition was first observed when running AutoCAD Release 9 and 10. The system may lock up when running software that uses the math co- processor after the system has warmed up (anywhere from immediately to 30 minutes). The failure is encountered consistently after re-booting until the system has been shut off and allowed to cool down. The cause of the problem is a contention with the 87BUSY* signal from the math co-processor. The contention situation is eliminated by lifting or cutting pin 16 on the chip at location U34 on the Premium 386/16 processor board (AST Part Number 202323-001). Denoted after the part number is a revision letter (i.e., 202323-001C). Use the following list to determine the appropriate action to be taken: Revision Action C or earlier You should return the board to AST for modification. D Modification may be performed by an AST Authorized Service Center. E or later Modification has already been implemented, and no action is required. WARNING: This operation is meant to be performed on Premium 386/16 processor boards only (AST Part Number 202323-001), NOT on Premium 386SX/16 or 386SX/20 processor boards. All modifications should be performed by an AST Authorized Service Center.