MC68020 Motorola, MC68020 Datasheet - Page 63

• Manufacturer Part Number: MC68020
• Description: (MC68020 / MC68EC020) MICROPROCESSORS USERS MANUAL
• Manufacturer: Motorola

Figures 5-12 and 5-13 show a word transfer (write) to an odd address in word-organized
memory. This example is similar to the one shown in Figures 5-9 and 5-10 except that the
operand is word sized and the transfer requires only two bus cycles. Figure 5-14 shows
the equivalent operation for a data read cycle.
5-16
31
Figure 5-12. Misaligned Word Operand Write to Word Port Example
OP0
15
D31
OP2
Figure 5-11. Misaligned Long-Word Operand Read
MSB
OP3
XXX
D31
WORD OPERAND
WORD MEMORY
LONG-WORD OPERAND (REGISTER)
DATA BUS
OP1
MSB
XXX
OP1
OP3
WORD MEMORY
DATA BUS
OP2
LSB
XXX
OP3
from Word Port Example
M68020 USER’S MANUAL
D16
OP0
OP2
XXX
LSB
OP2
0
D16
SIZ1 SIZ0 A2
1
0
MC68020/EC020
0
1
SIZ1 SIZ0 A2
OP3
0
0
0
1
0
MC68020/EC020
A1
0
1
0
1
1
0
A0
1
0
0
0
1
A1
0
1
0
MEMORY CONTROL
DSACK1
A0
1
0
0
L
L
DSACK0
MEMORY CONTROL
DSACK1
H
H
L
L
L
DSACK0
MOTOROLA
H
H
H