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Bus Operation
MOTOROLA M68060 USER’S MANUAL 7-69
In addition, the snoop address on A31–A0 is again registered on the next CLK (not BCLK)
rising edge. For proper operation, the snoop addresses registered on these two separate
occasions must be consistent. Only normal and MOVE16 bus transfers can be snooped.
The MC68060 then examines the address of the transfer and invalidates the line in its
caches in which the address matches. This process is done quietly without external indica-
tion that a cache entry has been invalidated. Note that when snooping is enabled and an
entry matches in the MC68060 caches, the entry is invalidated regardless of the state of the
R/W signal, transfer size, or whether or not the line has clean or dirty data. If SNOOP is
negated, no snooping is done, and no lines in the caches are invalidated.
Figure 7-45. Implicit Bus Ownership Arbitration Timing
BCLK
ALTERNATE
MASTER PROCESSOR
BUS
IMPLICITLY
OWNED
BUS OWNED
AND ACTIVE
BUS OWNED
AND IDLE
C1 C2 C3 C4 C5 C8 C9C6 C7
AM-EX AM-EX AM-EX IM-OWN IM-OWN EX-OWN EX-OWNEX-OWN EX-OWN
A31–A0
BUS
ARBITRATION
STATE
D31–D0
TRANSFER
ATTRIBUTES
TS
TA
BR
BG
BB
AM_BR*
AM_BG*
*
AM indicates the alternate bus master.
BTT
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