AMD-K6-2E Datasheet, PDF (120/332 Pages) Advanced Micro Devices – AMD-K6™-2E Embedded Processor

AMD-K6™-2E Processor Data Sheet
Preliminary Information
22529B/0—January 2000
5.21
EWBE# (External Write Buffer Empty)
Pin Attribute
Input
Pin Location
Summary
W-03
The system logic can negate EWBE# to the processor to indicate
that its external write buffers are full and that additional data
cannot be stored at this time. This causes the processor to delay
the following activities until EWBE# is sampled asserted:
s The commitment of write hit cycles to cache lines in the
modified state or exclusive state in the processor’s cache
s The decode and execution of an instruction that follows a
currently-executing serializing instruction
s The assertion or negation of SMIACT#
s The entering of the Halt state and the Stop Grant state
Negating EWBE# does not prevent the completion of any type
of cycle that is currently in progress.
Sampled
The processor samples EWBE# on each clock edge that BRDY#
is sampled asserted during all memory write cycles (except
writeback cycles), I/O write cycles, and special bus cycles.
If EWBE# is sampled negated, it is sampled on every clock edge
until it is asserted, and then it is ignored until BRDY # is
sampled asserted in the next write cycle or special cycle.
If EFER[3] is 1, then EWBE# is ignored by the processor. For
more information on the EFER settings and EWBE#, see
“EWBE# Control” on page 205.
102
Signal Descriptions
Chapter 5