AMD-K6-2E Datasheet, PDF (232/332 Pages) Advanced Micro Devices – AMD-K6™-2E Embedded Processor

AMD-K6™-2E Processor Data Sheet
Preliminary Information
22529B/0—January 2000
IGNNE# is used by the external hardware to control the effect
of an unmasked floating-point exception. Under certain
circumstances, if IGNNE# is sampled asserted, the processor
ignores the floating-point exception.
Figure 80 illustrates an implementation of external logic for
supporting floating-point exceptions. The following example
explains the operation of the external logic in Figure 80:
1. As the result of a floating-point exception, the processor
asserts FERR#.
2. The assertion of FERR# and the sampling of IGNNE#
negated indicates the processor has stopped instruction
execution and is waiting for an interrupt.
3. The assertion of FERR# leads to the assertion of INTR by
the interrupt controller.
4. The processor acknowledges the interrupt and jumps to the
corresponding interrupt service routine in which an I/O
write cycle to address port F0h leads to the assertion of
IGNNE#.
5. When IGNNE# is sampled asserted, the processor ignores
the floating-point exception and continues instruction
execution.
6. When the processor negates FERR#, the external logic
negates IGNNE#.
See “FERR# (Floating-Point Error)” on page 103 and “IGNNE#
(Ignore Numeric Exception)” on page 108 for more details.
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Floating-Point and Multimedia Execution Units
Chapter 10