MC68020 Motorola, MC68020 Datasheet - Page 55

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

Table 5-4 lists the bytes required on the data bus for read cycles. The entries shown as
OP3, OP2, OP1, and OP0 are portions of the requested operand that are read or written
during that bus cycle and are defined by SIZ1, SIZ0, A1, and A0 for the bus cycle.
5-8
Byte
Word
3 Bytes
Long Word
Transfer
Size
SIZ1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
Size
Table 5-4. Data Bus Requirements for Read Cycles
SIZ0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
A1
Address
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
A0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
D31–D24
M68020 USER’S MANUAL
OP3
OP2
OP1
OP0
External Data Bytes
D23–D16
Long-Word Port
OP3
OP3
OP2
OP2
OP1
OP1
OP0
Required
D15–D8
OP3
OP3
OP2
OP3
OP2
OP1
OP2
OP1
OP0
D7–D0
OP3
OP3
OP2
OP3
OP2
OP1
OP3
OP2
OP1
OP0
External Data Bytes
D31–D24
OP3
OP3
OP2
OP2
OP1
OP1
OP0
OP0
Word Port
Required
D23–D16
OP3
OP3
OP3
OP3
OP2
OP2
OP2
OP1
OP2
OP1
OP1
OP0
OP1
OP0
Data Bytes
MOTOROLA
Byte Port
Required
D31–D24
External
OP3
OP3
OP3
OP3
OP2
OP2
OP2
OP2
OP1
OP1
OP1
OP1
OP0
OP0
OP0
OP0