Misaligned Word Operand Write To Word Port Example - Motorola MC68020 User Manual

31
OP0
Figure 5-11. Misaligned Long-Word Operand Read
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.
15
OP2
D31
MSB
XXX
OP3
Figure 5-12. Misaligned Word Operand Write to Word Port Example
5-16
LONG-WORD OPERAND (REGISTER)
OP1 OP2
D31 DATA BUS
WORD MEMORY
MSB LSB
OP0
XXX
OP1 OP2
OP3 XXX
from Word Port Example
WORD OPERAND 0
OP3
DATA BUS D16
WORD MEMORY
LSB
OP2
XXX
M68020 USER'S MANUAL
0
OP3
D16
MC68020/EC020
SIZ1 SIZ0 A2 A1
0 0 0
1 1 0
0 1 1
MC68020/EC020
SIZ1 SIZ0 A2 A1 A0
1 0 0 0 1
0 1 0 1 0
MEMORY CONTROL
A0
DSACK1 DSACK0
0 1 L H
1 0
L H
0 0
L H
MEMORY CONTROL
DSACK1 DSACK0
L H
L H
MOTOROLA