MC68030 Datasheet, PDF (179/602 Pages) Motorola, Inc – ENHANCED 32-BIT MICROPROCESSOR

Bus Operation
CONTROLLER
ADDRESS DEVICE
1) ASSERT ECS/OCS FOR ONE-HALF CLOCK
2) SET R/W TO READ
3) DRIVE ADDRESS ON A31-A0
4) DRIVE FUNCTION CODE ON FC2-FC0
5) DRIVE SIZE (SIZ1-SIZ0) (FOUR BYTES)
6) CACHE INHIBIT OUT (CIOUT) BECOMES VALID
7) ASSERT ADDRESS STROBE (AS)
8) ASSERT DATA STROBE (DS)
9) ASSERT DATA BUFFER ENABLE (DBEN)
ACQUIRE DATA
1) SAMPLE CACHE IN (CIN)
2) LATCH DATA
3) NEGATE AS AND DS
4) NEGATE DBEN
START NEXT CYCLE
EXTERNAL DEVICE
PRESENT DATA
1) DECODE ADDRESS
2) PLACE DATA ON D31-D0
3) ASSERT DATA TRANSFER AND SIZE
ACKNOWLEDGE (DSACKx)
TERMINATE CYCLE
1) REMOVE DATA FROM D31-D0
2) NEGATE DSACK
Figure 7-19. Asynchronous Long-Word Read Cycle Flowchart
CONTROLLER
ADDRESS DEVICE
1) ASSERT ECS/OCS FOR ONE-HALF CLOCK
2) SET R/W TO READ
3) DRIVE ADDRESS ON A31-A0
4) DRIVE FUNCTION CODE ON FC2-FC0
5) DRIVE SIZE (SIZ1-SIZ0) (FOUR BYTES)
6) CACHE INHIBIT OUT (CIOUT) BECOMES VALID
7) ASSERT ADDRESS STROBE (AS)
8) ASSERT DATA STROBE (DS)
9) ASSERT DATA BUFFER ENABLE (DBEN)
ACQUIRE DATA
1)SAMPLE CACHE INHIBIT IN (CIIN)
2) LATCH DATA
3) NEGATE AS AND DS
4) NEGATE DBEN
EXTERNAL DEVICE
PRESENT DATA
1) DECODE ADDRESS
2) PLACE DATA ON D31-D324 OR
D23-D16 OR
D15-D8 OR
D7-D0
(BASED ON A1,A0, CACHE AND BUS WIDTH)
3) ASSERT DATA TRANSFER AND SIZE
ACKNOWLEDGE (DSACKx)
TERMINATE CYCLE
START NEXT CYCLE
1) REMOVE DATA FROM D31-D0
2) NEGATE DSACK
Figure 7-20. Asynchronous Byte Read Cycle Flowchart
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MC68030 USER’S MANUAL
MOTOROLA