Detailed Flowchart Of Descriptor Fetch Operation - Motorola M68060 User Manual

AT PA = TA + (INDEX*4)
(INDEX = RI, PI, OR PGI)
IF SCHEDULED, EXECUTE
WRITE ACCESS (U
PREVIOUS DESCRIPTOR
EXIT TABLE SEARCH
'INVALID'
RETURN
SCHEDULE
WRITE ACCESS
U
(SEE NOTE)
DUE TO ACCESS PIPELINING, A POINTER
NOTE :
DESCRIPTOR WRITE ACCESS TO UPDATE
THE U-BIT OCCURS AFTER THE READ OF
THE NEXT LEVEL DESCRIPTOR.
ABBREVIATIONS:
WP – ACCUMULATED WRITE-
PROTECTION STATUS
V – LOGICAL "OR" OPERATOR
– ASSIGNMENT OPERATOR
Figure 4-9. Detailed Flowchart of Descriptor Fetch Operation
MOTOROLA
FETCH DESCRIPTOR &
UPDATE HISTORY AND STATUS
TYPE = 'PAGE' OR 'POINTER'
FETCH DESCRIPTOR
1) FOR
(SEE NOTE)
OTHERWISE
NORMAL TERMINATION
OF ALL BUS TRANSFERS
TYPE =
'POINTER'
'RESIDENT'
WP = WP V W
U = 1
U = 0
1
RETURN
M68060 USER'S MANUAL
TYPE = 'INDIRECT'
FETCH DESCRIPTOR AT
PA = DESCRIPTOR ADDRESS
TYPE = 'PAGE'
OR 'INDIRECT'
'INVALID'
OR 'INDIRECT'
'RESIDENT'
WP = WP V W
READ ACCESS
WRITE ACCESS
U = 0 &
(WP = 1 OR M = 1)
U = 0
U = 1
EXECUTE
LOCKED
RMW ACCESS
U 1
NORMAL TERMINATION
OF ALL BUS TRANSFERS
RETURN
Memory Management Unit
RETURN
U = 1 &
(WP = 1 OR M = 1)
WP = 0 & M = 0
EXECUTE
WRITE ACCESS
U 1, M 1
OTHERWISE
EXIT TABLE SEARCH
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