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Caches
5-19
M68060 USER’S MANUAL
MOTOROLA
Table 5-3. Data Cache Line State Transitions
Cache
Operation
Current State
Invalid Cases Valid Cases Dirty Cases
OPU Read
Miss (C,W)I1
Read line from memory
and update cache; Sup-
ply data to OPU; Go to
valid state.
(C,W)V1
Read new line from mem-
ory and update cache;
supply data to OPU; Re-
main in current state.
CD1
Push dirty cache line to
push buffer; Read new
line from memory and up-
date cache; Supply data
to OPU; Write push buffer
contents to memory; Go
to valid state.
OPU Read
Hit (C,W)I2 Not possible. (C,W)V2 Supply data to OPU; Re-
main in current state. CD2 Supply data to OPU; Re-
main in current state.
OPU Write
Miss
(Copyback
Mode)
CI3
Read line from memory
and update cache; Write
data to cache; Go to dirty
state.
CV3
Read new line from mem-
ory and update cache;
Write data to cache; Go
to dirty state.
CD3
Push dirty cache line to
push buffer; Read new
line from memory and up-
date cache; Write push
buffer contents to memo-
ry; Remain in current
state.
OPU Write
Miss
(Writethrou
gh Mode)
WI3 Write data to memory;
Remain in current state. WV3 Write data to memory;
Remain in current state. WD
3Write data to memory;
Remain in current state.
OPU Write
Hit (Copy-
back Mode) CI4 Not possible. CV$ Write data to cache; Go
to dirty state. CD4 Write data to cache; Re-
main in current state.
OPU Write
Hit
(Writethrou
gh Mode)
WI4 Not possible. WV4 Write data to memory
and to cache; Remain in
current state.
WD
4
Push dirty cache line to
memory; Write data to
memory and to cache;
Go to valid state.
Cache In-
validate (C,W)I5 No action; Remain in cur-
rent state. (C,W)V5 No action; Go to invalid
state. CD5 No action (dirty data lost);
Go to invalid state.
Cache
Push (C,W)I6 No action; Remain in cur-
rent state. (C,W)V6 No action; Go to invalid
state. CD6
Push dirty cache line to
memory; Go to invalid
state or remain in current
state, depending on the
DPI bit the the CACR.
Alternate
Master
Snoop Hit (C,W)I7 Not possible. (C,W)V7 No action; Go to invalid
state. CD7 No action (dirty data lost);
Go to invalid state.
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