Exception Handling in a Highly Overlapped Machine
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Exceptions are difficult to handle in an overlapped machine. For example, certain machines can not define the position of the program counter at the time of an exception (imprecise interrupts). This in part is due to the floating point unit executing instructions being out of order. Highly overlapped machines will have more difficulty with exceptions. This article describes a mechanism for dealing with exceptions in highly overlapped machines. In a traditional architecture an exception causes a procedure call to occur immediately after (or in some cases before) the instruction causing the exception. This procedure call cannot be anticipated. In an overlapped machine, the I-unit may not know for some time that an exception has occurred in the E-unit.