Motorola M68000 User Manual page 40

BUS MASTER
ADDRESS THE DEVICE
1) SET R/W TO READ
2) PLACE FUNCTION CODE ON FC2–FC0
3) PLACE ADDRESS ON A23-A0
4) ASSERT ADDRESS STROBE (AS)
5) ASSERT LOWER DATA STROBE (LDS)
(DS ON MC68008)
ACQUIRE THE DATA
1) LATCH DATA
2) NEGATE LDS (DS FOR MC68008)
3) NEGATE AS
START NEXT CYCLE
S0 S1 S2 S3 S4 S5 S6 S7 S0 S1 S2 S3 S4 S5 S6 S7 S0 S1 S2 S3 S4 w
CLK
FC2–FC0
A23–A0
AS
(DS)
LDS
R/W
DTACK
D7–D0
Figure 4-2. Read and Write-Cycle Timing Diagram
4-2 M68000 8-/16-/32-BIT MICROPROCESSORS USER'S MANUAL
Freescale Semiconductor, Inc.
Figure 4-1. Byte Read-Cycle Flowchart
READ WRITE
For More Information On This Product,
Go to: www.freescale.com
SLAVE
INPUT THE DATA
1) DECODE ADDRESS
2) PLACE DATA ON D7–D0
3) ASSERT DATA TRANSFER
ACKNOWLEDGE (DTACK)
TERMINATE THE CYCLE
1) REMOVE DATA FROM D7–D0
2) NEGATE DTACK
w w w S5 S6 S7
2 WAIT STATE READ
MOTOROLA