EMBEDDED Intel486™ PROCESSOR HARDWARE REFERENCE MANUAL
4-68
Figure 4-46. Locked Cycles (Back-to-Back)
4.4.4.1 Snoop/Lock Collision
If there is a snoop cycle overlaying a locked cycle, the snoop write-back cycle fractures the
locked cycle. As shown in Figure 4-47, after the read portion of the locked cycle is completed,
the snoop write-back starts under HITM#. After the write-back is completed, the locked cycle
continues. But during all this time (including the write-back cycle), the LOCK# signal remains
asserted.
Because HOLD is not acknowledged if LOCK# is asserted, snoop-lock collisions are restricted
to AHOLD and BOFF# snooping.
242202-158
CLK
ADS#
DATA
Ti T1 T2 T1 T2 T1 T2 T1 T2 T1
To Processor
From Processor
RDY#
BRDY#
ADDR
CACHE#
LOCK#
W/R#
Rd1 Wt1 Rd2 Wt2
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