Data Cache Line State Transitions - Motorola M68060 User Manual

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