116
Signal Descriptions
Chapter 5
AMD-K6-2E+ Embedded Processor Data Sheet
23542A/0—September 2000
Preliminary Information
5.28
IGNNE# (Ignore Numeric Exception)
Pin Attribute
Input
Summary
IGNNE#, in conjunction with the numeric error (NE) bit in the
CR0 register, is used by the system logic to control the effect of
an unmaske d f l oating-p oint e x ception on a prev iou s
f l oat ing-p o in t in stru ct ion d u ri ng th e e x e c ut ion of a
flo a ting-p oint ins t ructi o n, M M X ins t ructio n, 3 DNow!
instruction, or the WAIT instruction—hereafter referred to as
the target instruction.
If an unmasked floating-point exception is pending and the
target instruction is considered error-sensitive, then the
relationship between NE and IGNNE# is as follows:
s
If NE = 0, then:
If IGNNE# is sampled asserted, the processor ignores the
floating-point
exception
and
continues
with
the
execution of the target instruction.
If IGNNE# is sampled negated, the processor waits until
it samples IGNNE#, INTR, SMI#, NMI, or INIT asserted.
If IGNNE# is sampled asserted while waiting, the
processor ignores the floating-point exception and
continues
with
the
execution
of
the
target
instruction.
If INTR, SMI#, NMI, or INIT is sampled asserted
while waiting, the processor handles its assertion
appropriately.
s
If NE = 1, the processor invokes the INT 10h exception
handler.
If an unmasked floating-point exception is pending and the
target instruction is considered error-insensitive, then the
processor ignores the floating-point exception and continues
with the execution of the target instruction.
FERR # is not affected by the state of the NE bit or IGNNE #.
FERR # is always asserted at the instruction boundary of the
target instruction that follows the floating-point instruction
that caused the unmasked floating-point exception.