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AST RESEARCH, INC. TECHNICAL BULLETIN #0654 12-21-90
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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.